© Semiconductor Components Industries, LLC, 2008
September, 2008 Rev. 4
1Publication Order Number:
NCP1395/D
NCP1395A/B
High Performance Resonant
Mode Controller
The NCP1395A/B offers everything needed to build a reliable and
rugged resonant mode power supply. Its unique architecture includes
a 1.0 MHz Voltage Controller Oscillator whose control mode brings
flexibility when an ORing function is a necessity, e.g. in multiple
feedback paths implementations. Protections featuring various
reaction times, e.g. immediate shutdown or timerbased event,
brownout, broken optocoupler detection etc., contribute to a safer
converter design, without engendering additional circuitry
complexity. An adjustable deadtime also helps lowering the
shootthrough current contribution as the switching frequency
increases.
Finally, an onboard operational transconductance amplifier allows
for various configurations, including constant output current working
mode or traditional voltage regulation.
Features
High Frequency Operation from 50 kHz up to 1.0 MHz
Selectable Minimum Switching Frequency with "3% Accuracy
Adjustable Deadtime from 150 ns to 1.0 ms
Startup Sequence via an Adjustable SoftStart
BrownOut Protection for a Simpler PFC Association
Latched Input for Severe Fault Conditions, e.g. Overtemperature
or OVP
TimerBased Input with AutoRecovery Operation for Delayed
Event Reaction
Enable Input for Immediate Event Reaction or Simple ON/OFF
Control
Operational Transconductance Amplifier (OTA) for Multiple
Feedback Loops
VCC Operation up to 20 V
Low Startup Current of 300 mA Max
Common Collector Optocoupler Connection
Internal Temperature Shutdown
B Version Features 10 V VCC Startup Threshold for Auxiliary
Supply Usage
Easy NoLoad Operation and Low Standby Power Due to
Programmable SkipCycle
These are PbFree Devices
Typical Applications
LCD/Plasma TV Converters
High Power AcDC Adapters for Notebooks
Industrial and Medical Power Sources
Offline Battery Chargers
PDIP16
P SUFFIX
CASE 648
PIN CONNECTIONS
http://onsemi.com
MARKING
DIAGRAMS
x = A or B
A = Assembly Location
WL = Wafer Lot
YY, Y = Year
WW = Work Week
G = PbFree Package
SO16
D SUFFIX
CASE 751B
1395xDR2G
AWLYWW
1
16
1
2
3
4
5
6
7
8
16
15
14
12
11
10
9
(Top View)
FB
Fmin
Fmax
DT
Css
Ctimer
BO
AGnd
NINV
Out
Vcc
B
PGnd
Slow Fault
A
13 Fast Fault
See detailed ordering and shipping information in the package
dimensions section on page 25 of this data sheet.
ORDERING INFORMATION
16
1
16
1
NCP1395xP
AWLYYWWG
NCP1395A/B
http://onsemi.com
2
NCP1395
Fmin
Fmax
Deadtime
Softstart
Timer
BO
Slow Fault
NCP5181
Power Ground
VCC = 15 V
HV
Analog Ground
+
Vout
Figure 1. Typical Application Example
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
1
2
3
4
8
7
6
5
NCP1395A/B
http://onsemi.com
3
PIN FUNCTION DESCRIPTION
Pin No. Symbol Function Description
1 Fmin Timing Resistor Connecting a resistor to this pin, sets the minimum oscillator frequency
reached for VFB is below 1.3 V.
2 Fmax Frequency Clamp A resistor sets the maximum frequency excursion.
3 DT Deadtime A simple resistor adjusts the deadtime length.
4 Css SoftStart Select the softstart duration.
5 FB Feedback Applying a voltage above 1.3 V on this pin increases the oscillation frequency
up to Fmax.
6 Ctimer Timer Duration Sets the timer duration in presence of a fault.
7 BO BrownOut Detects low input voltage conditions. When brought above Vlatch, it fully
latches off the controller.
8 Agnd Analog Ground
9 Pgnd Power Ground
10 A Low Side Output Drives the low side power MOSFET.
11 BHigh Side Output Drives the upper side power MOSFET.
12 Vcc Supplies the Controller
13 Fast Fault Quick Fault Detection Fast shutdown pin, stops all pulses when brought high. Please look in the
description for more details about the fastfault sequence.
14 Slow Fault Slow Fault Detection When asserted, the timer starts to countdown and shuts down the controller at
the end of its time duration.
15 OUT OPAMP Output Internal transconductance amplifier.
16 NINV OPAMP Noninverting Noninverting pin of the OPAMP.
NCP1395A/B
http://onsemi.com
4
Vref
Fmin
Vdd
Imin
Vfb = < Vfb_off
CIDT
+
+
DT Adj.
I = Imax for Vfb = 5 V
I = 0 for Vfb < Vfb_off
Vref
Vdd
Imin
Vfb = < Vfb_off
Vref
Vdd
Imax
Vfb = 5
Fmax
Vdd
Itimer
If FAULT Itimer else 0
+
Timer
+
Vref
PON
Reset
Fault
Vdd
ISS
SS
FB
RFB
+
+
Vfb_fault
+
G = 1 > 0 only if
V(FB) > Vfb_off
IDT
Vref
Vdd
+
Vfb_off
DT
Deadtime
Adjustment
Vdd
+
BO
+
VBO
AGND
+
+
Vlatch
20 ms Noise
Filter
Clk
D
S
Q
Q
R
S
Q
Q
R
PON Reset
50% DC
Temperature
Shutdown
VCC
Management
PON
Reset
Fault
Timeout
Fault
+
-
+
Vref_FB
Vref
gm
NINV
OUT
BO
Reset
FF
+
-
Slow
Fault
+
Vref Fault
SS Reset on
A Version Only
+
-
+
Vref Fault
Fast
Fault
20 V
VCC
Timeout
Fault
SS
UVLO
Fault
B
A
PGND
Figure 2. Internal Circuit Architecture
IBO
NCP1395A/B
http://onsemi.com
5
MAXIMUM RATINGS
Rating Symbol Value Unit
Power Supply Voltage, Pin 12 VCC 20 V
Transient Current Injected into VCC when Internal Zener is Activated –
Pulse Width < 10 ms
10 mA
Power Supply Voltage, All Pins (Except Pins 10 and 11) 0.3 to 10 V
Thermal Resistance, JunctiontoAir, PDIP Version RqJA 130 °C/W
Thermal Resistance, JunctiontoAir, SOIC Version RqJA 100 °C/W
Storage Temperature Range 60 to +150 °C
ESD Capability, Human Body Model 2 kV
ESD Capability, Machine Model 200 V
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. This device series contains ESD protection and exceeds the following tests:
Human Body Model 2000V per JESD22A114B
Machine Model Method 200V per JESD22A115A.
2. This device contains latchup protection and exceeds 100 mA per JEDEC Standard JESD78.
NCP1395A/B
http://onsemi.com
6
ELECTRICAL CHARACTERISTICS (For typical values Tj = 25°C, for min/max values Tj = 40°C to +125°C, Max TJ = 150°C,
VCC = 11 V, unless otherwise noted.)
Characteristic Pin Symbol Min Typ Max Unit
SUPPLY SECTION
TurnOn Threshold Level, VCC Going Up – A Version 12 VCCON 12.3 13.3 14.3 V
TurnOn Threshold Level, VCC Going Up – B Version 12 VCCON 9.3 10.3 11.3 V
Minimum Operating Voltage after TurnOn 12 VCC(min) 8.3 9.3 10.3 V
Minimum Hysteresis between VCCON and VCC(min) A Version 12 VhysteA 3.0 V
Minimum Hysteresis between VCCON and VCC(min) B Version 12 VhysteB 1.0 V
Startup Current, VCC < VCCON 12 Istartup 300 mA
VCC Level at which the Internal Logic gets Reset 12 VCCreset 5.9 V
Internal IC Consumption, No Output Load on Pins 11/12, Fsw = 300 kHz 12 ICC1 1.6 mA
Internal IC consumption, 100 pF output load on pin 11 / 12, Fsw = 300 kHz 12 ICC2 2.3 mA
Consumption in fault mode (All drivers disabled, Vcc > VCC(min) ) 12 ICC3 1.3 mA
VOLTAGE CONTROL OSCILLATOR (VCO)
Minimum Switching Frequency, Rt = 120 kW on Pin 1, Vpin 5 = 0 V,
DT = 300 ns
1Fsw min 48.5 50 51.5 kHz
Maximum Switching Frequency, Rfmax = 22 kW on Pin 2, Vpin 5 >
6.0 V, DT = 300 ns Tj = 25°C (Note 3)
2Fsw max 0.9 1.0 1.11 MHz
Feedback Pin Swing above which Df = 0 5 FBSW 6.0 V
VCO VCC Rejection, DVCC = 1.0 V, in Percentage of Fsw PSRR 0.2 %/V
Operating Duty Cycle 1110 DC 48 50 52 %
Reference Voltage for all Current Generations (Fosc, DT) 1, 3 VREF 1.86 2.0 2.14 V
Delay before any Driver Restart in Fault Mode Tdel 20 ms
FEEDBACK SECTION
Internal Pulldown Resistor 5 Rfb 20 kW
OTA Internal Offset Voltage 16 VREF_FB 2.325 2.5 2.675 V
Voltage on Pin 5 below which the FB Level has no VCO Action 5 Vfb_off 1.3 V
Voltage on Pin 5 below which the Controller Considers a Fault 5 Vfb_fault 0.6 V
Input Bias Current 16 IBias 100 nA
DC Transconductance Gain 15 OTAG 250 mS
Gain Product Bandwidth, Rload = 5.0 kW15 GBW 1.0 MHz
DRIVE OUTPUT
Output Voltage Rise Time @ CL = 100 pF, 1090% of Output Signal 1110 Tr20 ns
Output Voltage FallTime @ CL = 100 pF, 1090% of Output Signal 1110 Tf20 ns
Source Resistance 1110 ROH 20 60 120 W
Sink Resistance 1110 ROL 30 60 130 W
Deadtime with RDT = 127 kW from Pin 3 to GND 3 T_dead 270 300 390 ns
Maximum Deadtime with RDT = 540 kW from Pin 3 to GND 3 T_deadmax 1.0 ms
Minimum Deadtime, RDT = 30 kW from Pin 3 to GND 3 T_deadmin 150 ns
3. Room temperature only, please look at characterization data for evolution versus junction temperature.
NCP1395A/B
http://onsemi.com
7
ELECTRICAL CHARACTERISTICS (continued) (For typical values Tj = 25°C, for min/max values Tj = 40°C to +125°C,
Max TJ = 150°C, VCC = 11 V, unless otherwise noted.)
Characteristic Pin Symbol Min Typ Max Unit
TIMERS
Timer Charge Current 6 Itimer 150 mA
Timer Duration with a 1.0 mF Capacitor and a 1.0 MW Resistor 6 Ttimer 25 ms
Timer Recurrence in Permanent Fault, Same Values as Above 6 TtimerR 1.4 s
Voltage at which Pin 6 Stops Output Pulses 6 VtimerON 3.7 4.1 4.5 V
Voltage at which Pin 6 Restarts Output Pulses 6 VtimerOFF 0.9 1.0 1.1 V
SoftStart Ending Voltage, VFB = 1.0 V 4 VSS 2.0 V
SoftStart Charge Current 4 ISS 75
Note 5
95 115 mA
SoftStart Duration with a 220 nF Capacitor (Note 4) 4 TSS 5.0 ms
PROTECTION
Reference Voltage for Fast Input 13 VrefFaultF 1.0 1.05 1.1 V
Reference Voltage for Slow Input 14 VrefFaultS 0.98 1.03 1.08 V
Hysteresis for Fast Input 13 HysteFaultF 50 mV
Hysteresis for Slow Input 14 HysteFaultS 40 mV
Propagation Delay for Fast Fault Input Drive Shutdown 13 TpFault 70 120 ns
BrownOut Input Bias Current 7 IBObias 0.02 mA
BrownOut Level 7 VBO 0.98 1.03 1.08 V
Hysteresis Current, Vpin 7 > VBO – A Version 7 IBO_A 23 28 33 mA
Hysteresis Current, Vpin 7 > VBO – B Version 7 IBO_B 70 83 96 mA
Latching Voltage 7 Vlatch 3.7 4.1 4.5 V
Temperature Shutdown TSD 140 °C
Hysteresis TSDhyste 40 °C
4. The A version does not activate softstart when the fastfault is released, this is for skip cycle implementation. The B version does activate
the softstart upon release of the fastfault input.
5. Minimum current occurs at TJ = 0°C.
NCP1395A/B
http://onsemi.com
8
TYPICAL CHARACTERISTICS A VERSION
Figure 3. VCCon A Figure 4. VCCmin
Figure 5. Fsw min Figure 6. Fsw max
Figure 7. Reference (Vref_FB)Figure 8. Pulldown Resistor (RFB)
13.0
13.1
13.2
13.3
13.4
13.5
40 20 80
VOLTAGE (V)
TEMPERATURE (°C)
1400 60 12020 40 100 9.0
9.2
9.4
9.6
9.8
10
40 20 80
VOLTAGE (V)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
48
48.5
49
49.5
50
40 20 80
FREQUENCY (kHz)
TEMPERATURE (°C)
1400 60 12020 40 100 0.7
0.8
0.9
1.0
1.1
40 20 80
FREQUENCY (MHz)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
18
19
20
21
22
23
40 20 80
RFB (kW)
TEMPERATURE (°C)
1400 60 12020 40 100 2.50
2.55
2.60
2.65
2.70
40 20 80
Vref_FB (V)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
NCP1395A/B
http://onsemi.com
9
TYPICAL CHARACTERISTICS A VERSION
Figure 9. Source Resistance (ROH) Figure 10. Sink Resistance (ROL)
Figure 11. T_dead_min A Figure 12. T_dead_A
Figure 13. Fast Fault (VrefFault FF)Figure 14. T_dead_max A
40
50
60
70
80
90
40 20 80
ROH (W)
TEMPERATURE (°C)
1400 60 12020 40 100
130
150
170
190
210
40 20 80
DT_min (ns)
TEMPERATURE (°C)
1400 60 12020 40 100 300
310
320
330
350
40 20 80
DT_nom (ns)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
100
40
50
60
70
80
90
40 20 80
ROL (W)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
100
110
230
250
340
700
800
900
1000
1100
40 20 80
DT_max (ns)
TEMPERATURE (°C)
1400 60 12020 40 100 1.00
1.02
1.04
1.06
1.10
40 20 80
VrefFaultFF (V)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
1200
1300
1.08
NCP1395A/B
http://onsemi.com
10
TYPICAL CHARACTERISTICS A VERSION
Figure 15. BrownOut Reference (VBO) Figure 16. BrownOut Hysteresis Current (IBO)
Figure 17. Latch Level (Vlatch)
1.02
1.025
1.03
1.035
1.04
40 20 80
VBO (V)
TEMPERATURE (°C)
1400 60 12020 40 100
4.0
4.05
4.1
4.15
4.2
40 20 80
Vlatch (V)
TEMPERATURE (°C)
1400 60 12020 40 100
25
26
27
28
29
30
40 20 80
IBO (mA)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
NCP1395A/B
http://onsemi.com
11
TYPICAL CHARACTERISTICS B VERSION
Figure 18. VCCon B Figure 19. VCCmin
Figure 20. Fsw min Figure 21. Fsw max
Figure 22. Reference (Vref_FB)Figure 23. Pulldown Resistor (RFB)
10
10.2
10.4
10.6
10.8
11
40 20 80
VCCon (V)
TEMPERATURE (°C)
1400 60 12020 40 100 9.0
9.2
9.4
9.6
9.8
10
40 20 80
VCCmin (V)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
48
48.5
49
49.5
50
40 20 80
FREQUENCY (kHz)
TEMPERATURE (°C)
1400 60 12020 40 100 0.7
0.8
0.9
1.0
1.1
40 20 80
FREQUENCY (MHz)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
18
19
20
21
22
23
40 20 80
RFB (kW)
TEMPERATURE (°C)
1400 60 12020 40 100 2.50
2.55
2.60
2.65
2.70
40 20 80
Vref_FB (V)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
NCP1395A/B
http://onsemi.com
12
TYPICAL CHARACTERISTICS B VERSION
Figure 24. Source Resistance (ROH) Figure 25. Sink Resistance (ROL)
Figure 26. T_dead_min B Figure 27. T_dead_B
Figure 28. Fast Fault (VrefFault FF)Figure 29. T_dead_max B
40
50
60
70
80
90
40 20 80
ROH (W)
TEMPERATURE (°C)
1400 60 12020 40 100
130
150
170
190
210
40 20 80
DT_min (ns)
TEMPERATURE (°C)
1400 60 12020 40 100 300
310
320
330
350
40 20 80
DT_nom (ns)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
100
40
50
60
70
80
90
40 20 80
ROL (W)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
100
110
230
250
340
700
800
900
1000
1100
40 20 80
DT_max (ns)
TEMPERATURE (°C)
1400 60 12020 40 100 1.00
1.02
1.04
1.06
1.10
40 20 80
VrefFaultFF (V)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
1200
1300
1.08
NCP1395A/B
http://onsemi.com
13
TYPICAL CHARACTERISTICS B VERSION
Figure 30. BrownOut Reference (VBO) Figure 31. BrownOut Hysteresis Current (IBO)
Figure 32. Latch Level (Vlatch)
1.02
1.025
1.03
1.035
1.04
40 20 80
VBO (V)
TEMPERATURE (°C)
1400 60 12020 40 100
4.0
4.05
4.1
4.15
4.2
40 20 80
Vlatch (V)
TEMPERATURE (°C)
1400 60 12020 40 100
70
75
80
85
90
40 20 80
IBO (mA)
TEMPERATURE (°C)
14
0
0 60 12020 40 100
NCP1395A/B
http://onsemi.com
14
APPLICATION INFORMATION
The NCP1395A/B includes all necessary features to help
build a rugged and safe switchmode power supply
featuring an extremely low standby power. The below
bullets detail the benefits brought by implementing the
NCP1395A/B controller:
Wide Frequency Range: A highspeed Voltage
Control Oscillator allows an output frequency
excursion from 50 kHz up to 1.0 MHz on A and B
outputs.
Adjustable Deadtime: Due to a single resistor wired
to ground, the user has the ability to include some
deadtime, helping to fight crossconduction between
the upper and the lower transistor.
Adjustable SoftStart: Every time the controller
starts to operate (power on), the switching frequency is
pushed to the programmed maximum value and slowly
moves down toward the minimum frequency, until the
feedback loop closes. The softstart sequence is
activated in the following cases: a) normal startup
b) back to operation from an off state: during hiccup
faulty mode, brownout or temperature shutdown
(TSD). In the NCP1395A, the softstart is not
activated back to operation from the fast fault input,
unless the feedback pin voltage reaches 0.6 V. To the
opposite, in the B version, the softstart is always
activated back from the fast fault input whatever the
feedback level is.
Adjustable Minimum and Maximum Frequency
Excursion: In resonant applications, it is important to
stay away from the resonating peak to keep operating
the converter in the right region. Due to a single
external resistor, the designer can program its lowest
frequency point, obtained in lack of feedback voltage
(during the startup sequence or in shortcircuit
conditions). Internally trimmed capacitors offer a
"3% precision on the selection of the minimum
switching frequency. The adjustable upper stop being
less precise to "15%.
Low Startup Current: When directly powered from
the highvoltage DC rail, the device only requires
300 mA to startup. In case of an auxiliary supply, the
B version offers a lower startup threshold to cope with
a 12 V dc rail.
BrownOut Detection: To avoid operation from a
low input voltage, it is interesting to prevent the
controller from switching if the highvoltage rail is
not within the right boundaries. Also, when teamed
with a PFC frontend circuitry, the brownout
detection can ensure a clean startup sequence with
softstart, ensuring that the PFC is stabilized before
energizing the resonant tank. The A version features a
28 mA hysteresis current for the lowest consumption
and the B version slightly increases this current to
83 mA in order to improve the noise immunity.
Adjustable Fault Timer Duration: When a fault is
detected on the slow fault input or when the FB path is
broken, a timer starts to charge an external capacitor.
If the fault is removed, the timer opens the charging
path and nothing happens. When the timer reaches its
selected duration (via a capacitor on pin 6), all pulses
are stopped. The controller now waits for the
discharge via an external resistor of pin 6 capacitor to
issue a new clean startup sequence with softstart.
Cumulative Fault Events: In the NCP1395A/B, the
timer capacitor is not reset when the fault disappears.
It actually integrates the information and cumulates
the occurrences. A resistor placed in parallel with the
capacitor will offer a simple way to adjust the
discharge rate and thus the autorecovery retry rate.
Fast and Slow Fault Detection: In some application,
subject to heavy load transients, it is interesting to
give a certain time to the fault circuit, before
activating the protection. On the other hand, some
critical faults cannot accept any delay before a
corrective action is taken. For this reason, the
NCP1395A/B includes a fast fault and a slow fault
input. Upon assertion, the fast fault immediately stops
all pulses and stays in the position as long as the
driving signal is high. When released low (the fault
has gone), the controller has several choices: in the
A version, pulses are back to a level imposed by the
feedback pin without softstart, but in the B version,
pulses are back through a regular softstart sequence.
Skip Cycle Possibility: The absence of softstart on
the NCP1395A fast fault input offers an easy way to
implement skip cycle when power saving features are
necessary. A simple resistive connection from the
feedback pin to the fast fault input, and skip can be
implemented.
Onboard Transconductance Op Amp: A
transconductance amplifier is used to implement
various options, like monitoring the output current and
maintaining it constant.
Broken Feedback Loop Detection: Upon startup or
any time during operation, if the FB signal is missing,
the timer starts to charge a capacitor. If the loop is
really broken, the FB level does not grow up before
the timer ends counting. The controller then stops all
pulses and waits that the timer pin voltage collapses to
1.0 V typically before a new attempt to restart, via the
softstart. If the optocoupler is permanently broken, a
hiccup takes place.
NCP1395A/B
http://onsemi.com
15
Finally, Two Circuit Versions, A and B: The A and
B versions differ because of the following changes:
1. The startup thresholds are different, the A starts
to pulse for VCC = 12.8 V whereas the B pulses
for VCC = 10 V. The turn off levels are the
same, however. The A is recommended for
consumer products where the designer can use
an external startup resistor, whereas the B is
more recommended for industrial/medical
applications where a 12 V auxiliary supply
directly powers the chip.
2. The A version does not activate the softstart
upon release of the fast fault input. This is to let
the designer implement skip cycle. To the
opposite, the B version goes back to operation
upon the fast fault pin release via a softstart
sequence.
VoltageControlled Oscillator
The VCO section features a highspeed circuitry
allowing an internal operation from 100 kHz up to
2.0 MHz. However, as a division by two internally creates
the two Q and Qbar outputs, the final effective signal on
output A and B switches between 50 kHz and 1.0 MHz.
The VCO is configured in such a way that if the feedback
pin goes up, the switching frequency also goes up.
Figure 33 shows the architecture of this oscillator.
Vref
Vdd
Fmin
Rtm sets
Fmin for V(FB) < Vfb_off Cint
Imin
+
-
0 to I_Fmax
IDT
FBinternal
max
Fsw
max
+
-
+
Clk
D
S
Q
Q
R
AB
Vref
Vdd
Rdt sets
the deadtime
DT
Imin
Vdd
Fmax
Rtmax sets
the maximum Fsw
Vcc
FB
Rfb
20 k
+
-
+
Vfb < Vb_fault
start fault timer
Figure 33. Simplified VCO Architecture
Vb_fault
NCP1395A/B
http://onsemi.com
16
The designer needs to program the maximum switching
frequency and the minimum switching frequency. In LLC
configurations, for circuits working above the resonant
frequency, a high precision is required on the minimum
frequency, hence the "3% specification. This minimum
switching frequency is actually reached when no feedback
closes the loop. It can happen during the startup sequence,
a strong output transient loading or in a shortcircuit
condition. By installing a resistor from pin 1 to AGND, the
minimum frequency is set. Using the same philosophy,
wiring a resistor from pin 2 to AGND will set the maximum
frequency excursion. To improve the circuit protection
features, we have purposely created a dead zone, where the
feedback loop has no action. This is typically below 1.3 V.
Figure 34 details the arrangement where the internal
voltage (that drives the VCO) varies between 0 and 3.6 V.
However, to create this swing, the feedback pin (to which
the optocoupler emitter connects), will need to swing
typically between 1.3 V and 6.0 V.
VCC
FB
Rfb
+
To VCO
0 to 3.6 V
+
1.3 V
VFB = 1.36 V
Figure 34. The OPAMP arrangement limits the VCO
internal modulation signal between 0 and 5.0 V.
This technique allows us to detect a fault on the converter
in case the FB pin cannot rise above 1.3 V (to actually close
the loop) in less than a duration imposed by the
programmable timer. Please refer to the fault section for
detailed operation of this mode.
As shown in Figure 34, the internal dynamics of the
VCO control voltage will be constrained between 0 V and
3.6 V, whereas the feedback loop will drive pin 5 (FB)
between 1.3 V and 6.0 V. If we take the external excursion
numbers, 1.3 V = 50 kHz, 6.0 V = 1.0 MHz, then the VCO
slope will then be 1Meg50 k
4.7 +202 kHzńV.
Figures 35 and 36 portray the frequency evolution
depending on the feedback pin voltage level in a different
frequency clamp combination.
VFB
FA&B
1.3 V 6 V
Fmin
Fmax
Î
Fault
area
ÏÏÏÏ
ÏÏÏÏ
ÏÏÏÏ
No variations
50 kHz
1 MHz
DFsw = 950 kHz
DVFB = 4.7V
0.6 V
VFB
FA&B
1.3 V 6 V
Fmin
Fmax
Ì
Fault
area
ÑÑÑÑ
ÑÑÑÑ
ÑÑÑÑ
No variations
50 kHz
1 MHz
DFsw = 950 kHz
DVFB = 4.7V
0.6 V
Figure 35. Maximal default excursion, Rt = 120 kW
on pin 1 and Rfmax = 35 kW on pin 2.
Ó
Ó
VFB
1.3 V 6 V
Fmin
Fmax
Fault
area
ÔÔÔÔ
ÔÔÔÔ
No variations
150 kHz
450 kHz
DFsw = 300 kHz
DVFB = 4.7 V
FA&B
0.6 V
Ö
Ö
VFB
1.3 V 6 V
Fmin
Fmax
Fault
area
ÒÒÒÒ
ÒÒÒÒ
No variations
150 kHz
450 kHz
DFsw = 300 kHz
DVFB = 4.7 V
FA&B
0.6 V
Figure 36. Here a different minimum frequency
was programmed as well as a different maximum
frequency excursion.
Please note that the previous small signal VCO slope has
now been reduced to 300 k/5.0 = 62.5 kHz/V. This offers
a mean to magnify the feedback excursion on systems
where the load range does not generate a wide switching
frequency excursion. Due to this option, we will see how
it becomes possible to observe the feedback level and
implement skip cycle at light loads. It is important to note
that the frequency evolution does not have a real linear
relationship with the feedback voltage. This is due to the
deadtime presence which stays constant as the switching
period changes.
NCP1395A/B
http://onsemi.com
17
The selection of the three setting resistors (Fmax, Fmin
and deadtime) requires the usage of the selection charts
displayed below:
Figure 37. Maximum switching frequency resistor
selection depending on the adopted minimum
switching frequency.
100
300
500
700
900
20 170 320
Fmax (kHz)
RFmax (kW)
120 27070 220 370
1100
Fmin = 200 kHz
Fmin = 50 kHz
VCC = 11 V
FB = 6.5 V
DT = 300 ns
Figure 38. Minimum Switching Frequency Resistor
Selection
40
60
80
100
120
20 80
Fmin (kHz)
RFmin (kW)
60 12040 100
140
VCC = 11 V
FB = 1 V
DT = 300 ns
160
180
200
Figure 39. DeadTime Resistor Selection
0
100
200
300
400
500
0 300 600
DT (ns)
Rdt (kW)
200 500100 400
600
700
800
900
1000
1100
VCC = 11 V
ORing Capability
If for a particular reason, there is a need for having a
frequency variation linked to an event appearance (instead
of abruptly stopping pulses), then the FB pin lends itself
very well to the addition of other sweeping loops. Several
diodes can easily be used to perform the job in case of
reaction to a fault event or to regulate on the output current
(CC operation). Figure 40 shows how to do it.
VCC
FBIn1
In2 20 k
VCO
Figure 40. Due to the FB configuration, loop ORing
is easy to implement.
NCP1395A/B
http://onsemi.com
18
Deadtime Control
Deadtime control is an absolute necessity when the
halfbridge configuration comes to play. The deadtime
technique consists of inserting a period during which both
high and low side switches are off. Of course, the deadtime
amount differs depending on the switching frequency,
hence the ability to adjust it on this controller. The option
ranges between 150 ns and 1.0 ms. The deadtime is actually
made by controlling the oscillator discharge current.
Figure 41 portrays a simplified VCO circuit based on
Figure 33.
Vdd
Icharge:
Fsw min + Fsw max
Idis
Ct
RDT
DT
Vref
+3 V1 V
+Clk
D
S
Q
Q
R
AB
Figure 41. Deadtime Generation
During the discharge time, the clock comparator is high
and unvalidates the AND gates: both outputs are low. When
the comparator goes back to the high level, during the
timing capacitor Ct recharge time, A and B outputs are
validated. By connecting a resistor RDT to ground, it
creates a current whose image serves to discharge the Ct
capacitor: we control the deadtime. The typical range
evolves between 150 ns (RDT = 30 kW) and 1.0 ms (RDT
= 600 kW). Figure 44 shows the typical waveforms
obtained on the output.
SoftStart Sequence
In resonant controllers, a softstart is needed to avoid
suddenly applying the full current into the resonating
circuit. In this controller, a softstart capacitor connects to
pin 4 and offers a smooth frequency variation upon startup:
when the circuit starts to pulse, the VCO is pushed to the
maximum switching frequency imposed by pin 2. Then, it
linearly decreases its frequency toward the minimum
frequency selected by a resistor on pin 1. Of course,
practically, the feedback loop is suppose to take over the
VCO lead as soon as the output voltage has reached the
target. If not, then the minimum switching frequency is
reached and a fault is detected on the feedback pin
(typically below 600 mV). Figure 43 depicts a typical
frequency evolution with softstart.
NCP1395A/B
http://onsemi.com
19
1ires1 2vout
20.0
10.0
0
10.0
20.0
ires1 in amperes
Plot1
1
200u 600u 1.00m 1.40m 1.80m
time in seconds
169
171
173
175
177
vout in volts
Plot2
2
SS Action Ires
Target is
reached
Vout
Figure 42. SoftStart Behavior Figure 43. A Typical Startup Sequence on an LLC
Converter
Please note that the softstart will be activated in the
following conditions:
A startup sequence
During autorecovery burst mode
A brownout recovery
A temperature shutdown recovery
The fast fault input undergoes a special treatment. Since
we want to implement skip cycle through the fast fault
input on the NCP1395A, we cannot activate the softstart
every time the feedback pin stops the operations in low
power mode. Therefore, when the fast fault pin is released,
no softstart occurs to offer the best skip cycle behavior.
However, it is very possible to combine skip cycle and true
fast fault input, e.g. via ORing diodes driving pin 13. In that
case, if a signal maintains the fast fault input high long
enough to bring the feedback level down (that is to say
below 0.6 V) since the output voltage starts to fall down,
then the softstart is activated after the release of the pin.
In the B version tailored to operate from an auxiliary
12 V power supply, the softstart is always activated upon
the fast fault input release, whatever the feedback
condition is.
NCP1395A/B
http://onsemi.com
20
1vct 2clock 5difference
0
1.00
2.00
3.00
4.00
vct in volts
plot1
1
0
4.00
8.00
12.0
16.0
clock in volts
plot2
2
56.2u 65.9u 75.7u 85.4u 95.1u
time in seconds
8.00
4.00
0
4.00
8.00
difference in volts
Plot3
5
Figure 44. Typical Oscillator Waveforms
BrownOut Protection
The BrownOut circuitry (BO) offers a way to protect the
resonant converter from low DC input voltages. Below a
given level, the controller blocks the output pulses, above
it, it authorizes them. The internal circuitry, depicted by
Figure 42, offers a possibility to observe the highvoltage
(HV) rail. A resistive divider made of Rupper and Rlower,
brings a portion of the HV rail on pin 7. Below the turnon
level, a current source IBO is off. Therefore, the turnon
level solely depends on the division ratio brought by the
resistive divider.
1vin 2vcmp
20.0u 60.0u 100u 140u 180u
time in seconds
0
4.00
8.00
12.0
16.0
vcmp in volts
50.0
150
250
350
450
vin in volts
Plot1
1
2
250 volts
351 volts
Vin
BO
Figure 45. The Internal BrownOut
Configuration with an Offset Current Source
Vdd
+
VBO
+
ON/OFF
IBO
BO
Vbulk
Rupper
Rlower
BO
Figure 46. Simulation Results for 350/250 ON/OFF Levels
NCP1395A/B
http://onsemi.com
21
To the contrary, when the internal BO signal is high
(A and B pulse), the IBO source is activated and creates
a hysteresis. The hysteresis level actually depends
on the circuit: NCP1395A features a 28 mA whereas
the NCP1395B uses a 83 mA current. Changes are
implemented to a) reduce the standby power on the
NCP1395A b) improve the noise immunity on the
NCP1395B. Knowing these values, it becomes possible to
select the turnon and turnoff levels via a few lines of
algebra:
IBO is off
V())+Vbulk1 Rlower
Rlower )Rupper (eq. 1)
IBO is on
V())+Vbulk2 Rlower
Rlower )Rupper )IBO ǒRlower Rupper
Rlower )RupperǓ(eq. 2)
We can now extract Rlower from Equation 1 and plug it
into Equation 2, then solve for Rupper:
Rupper +Rlower Vbulk1VBO
VBO
Rlower +VBO Vbulk1Vbulk2
IBO (Vbulk1VBO)
If we decide to turn on our converter for Vbulk1 equals
350 V, and turn it off for Vbulk2 equals 250 V, then we
obtain:
IBO = 28 mA
Rupper = 3.6 MW
Rlower = 10 kW
The bridge power dissipation is 4002/3.601 MW =
45 mW when the frontend PFC stage delivers 400 V.
IBO = 83 mA
Rupper = 1.2 MW
Rlower = 3.4 kW
The bridge power dissipation is 132 mW when the
frontend PFC stage delivers 400 V. Figure 46 simulation
result confirms our calculations.
LatchOff Protection
There are some situations where the converter shall be
fully turned off and stay latched. This can happen in
presence of an overvoltage (the feedback loop is drifting)
or when an overtemperature is detected. Due to the addition
of a comparator on the BO pin, a simple external circuit can
lift up this pin above VLATCH (5.0 V typical) and
permanently disable pulses. The VCC needs to be cycled
down below 5.0 V typically to reset the controller.
+
20 ms
RC To permanent
latch
+
Vlatch
Vdd
+BO
+
VBO
BO
Rlower
Rupper
VbulkVCC
Q1
NTC
Vout
Figure 47. Adding a comparator on the BO pin offers a way to latchoff the controller.
IBO
In Figure 47, Q1 is blocked and does not bother the BO
measurement as long as the NTC and the optocoupler are
not activated. As soon as the secondary optocoupler senses
an OVP condition, or the NTC reacts to a high ambient
temperature, Q1 base is brought to ground and the BO pin
goes up, permanently latching off the controller.
NCP1395A/B
http://onsemi.com
22
Protection Circuitry
This resonant controller differs from competitors due to
its protection features. The device can react to various
inputs like:
Fast events input: Like an overcurrent condition, a
need to shutdown (sleep mode) or a way to force a
controlled burst mode (skip cycle at low output
power): as soon as the input level exceeds 1.0 V
typical, pulses are immediately stopped. On the
A version, when the input is released, the controller
performs a clean startup sequence without softstart
unless the feedback voltage goes down below 0.6 V
during fault time (please see above for details). The
B version restarts with a softstart sequence.
Slow events input: This input serves as a delayed
shutdown, where an event like a transient overload
does not immediately stopped pulses but start a timer.
If the event duration lasts longer than what the timer
imposes, then all pulses are disabled. The voltage on
the timer capacitor (pin 3) starts to decrease until it
reaches 1.0 V. The decrease rate is actually depending
on the resistor the user will put in parallel with the
capacitor, giving another flexibility during design.
Figure 48 depicts the architecture of the fault circuitry.
Vdd
Itimer
Reset
UVLO
Output
Current
Image
Rtimer
CtimerCtimer
NINV
+
-
ON/OFF
1 = fault
0 = ok
+
Vref Fault
+-
+
VtimerON
VtimerOFF
1 = ok
0 = fault
+
-
Vref Fault
+
-
+
Vref
Out CC Regulation
Compensation
Slow Fault
Fast Fault
+
1 = ok
0 = fault
DRIVING
LOGIC
SS
AA
BB
Reset
To FB
Fast
Input
Figure 48. This Circuit Combines a Slow and Fast Input for Improved Protection Features
NCP1395A/B
http://onsemi.com
23
In this figure, the internal OPAMP is used to perform a
kind of constant current operation (CC) by taking the lead
when the other voltage loop is gone (CV). Due to the ORing
capability on the FB pin, the OPAMP regulates in constant
current mode. When the output reaches a low level close to
a complete shortcircuit, the OPAMP output is maximum.
With a resistive divider on the slow fault, this condition can
be detected to trigger the delayed fault. If no OPAMP shall
be used, its input must be grounded.
Slow Input
On this circuit, the slow input goes to a comparator.
When this input exceeds 1.0 V typical, the current source
Itimer turns on, charging the external capacitor Ctimer. If
the fault duration is long enough, when Ctimer voltage
reaches the VtimerON level (4.0 V typical), then all pulses
are stopped. Itimer turns off and the capacitor slowly
discharges to ground via a resistor installed in parallel with
it. As a result, the designer can easily determine the time
during which the power supply stays locked by playing on
Rtimer. Now, when the timer capacitor voltage reaches
1.0 V typical (VtimerOFF), the comparator instructs the
internal logic to issues pulses as on a clean softstart
sequence (softstart is activated). Please note that the
discharge resistor cannot be lower than 4.0 V/Itimer,
otherwise the voltage on Ctimer will never reach the
turnoff voltage of 4.0 V.
In both cases, when the fault is validated, both outputs A
and B are internally pulled down to ground.
Fast Fault
FB
VCC
Figure 49. A resistor can easily program the capacitor discharge time. Figure 50. Skip cycle can be
implemented via two
resistors on the FB pin to the
fast fault input.
Fast Input
The fast input is not affected by a delayed action. As soon
as its voltage exceeds 1.0 V typical, all pulses are off and
maintained off as long as the fault is present. When the pin
is released, pulses come back without softstart for the
A version, with softstart for the B version.
Due to the low activation level of 1.0 V, this pin can
observe the feedback pin via a resistive divided and thus
implement skip cycle operation. The resonant converter
can be designed to lose regulation in light load conditions,
forcing the FB level to increase. When it reaches the
programmed level, it triggers the fast fault input and stops
pulses. Then Vout slowly drops, the loop reacts by
decreasing the feedback level which, in turn, unlocks the
pulses: Vout goes up again and so on: we are in skip cycle
mode.
Startup Behavior
When the VCC voltage grows up, the internal current
consumption is kept to Istup, allowing to crank up the
converter via a resistor connected to the bulk capacitor.
When VCC reaches the VCCON level, output A goes high
first and then output B. This sequence will always be the
same, whatever triggers the pulse delivery: fault, OFF to
ON etc Pulsing the output A high first gives an
immediate charge of the bootstrap capacitor when an
integrated high voltage halfbridge driver is implemented
such as ON Semiconductors NCP5181. Then, the rest of
pulses follow, delivered at the highest switching value, set
by the resistor on pin 2. The softstart capacitor ensures a
smooth frequency decrease to either the programmed
minimum value (in case of fault) or to a value
corresponding to the operating point if the feedback loop
closes first. Figure 51 shows typical signals evolution at
power on.
NCP1395A/B
http://onsemi.com
24
SS
TSS
FB
A B
A&B
Timer
Fault!
0.6V
Slopes are similar
A B
4V
1V
Vcc from an auxiliary supply
TSS
VCCON
VCC(min)
SS
TSS
FB
A B
A&B
Timer
Fault!
0.6V
Slopes are similar
A B
4V
1V
Vcc from an auxiliary supply
TSS
VCCON
VCC(min)
Figure 51. At power on, output A is first activated and the frequency slowly
decreases via the softstart capacitor.
Figure 51 depicts an autorecovery situation, where the
timer has triggered the end of output pulses. In that case, the
VCC level was given by an auxiliary power supply, hence
its stability during the hiccup. A similar situation can arise
if the user selects a more traditional startup method,
with an auxiliary winding. In that case, the VCC(min)
comparator stops the output pulses whenever it is activated,
that is to say, when VCC falls below 10.3 V typical. At this
time, the VCC pin still receives its bias current from the
startup resistor and heads toward VCCON via the Vcc
capacitor. When the voltage reaches VCCON, a standard
sequence takes place, involving a softstart. Figure 52
portrays this behavior.
NCP1395A/B
http://onsemi.com
25
VCCON
SS
TSS
FB
A B
A&B
Timer
Fault!
0.6V
A B
4V
1V
Vcc from a startup resistor
TSS
VCC(min)
Fault is
released
VCCON
SS
TSS
FB
A B
A&B
Timer
Fault!
0.6V
A B
4V
1V
Vcc from a startup resistor
TSS
VCC(min)
Fault is
released
Figure 52. When the VCC is too low, all pulses are stopped until VCC goes back
to the startup voltage.
As described in the data sheet, two startup levels VCCON
are available, via two circuit versions. The NCP1395A
features a large hysteresis to allow a classical startup
method with a resistor connected to the bulk capacitor.
Then, at the end of the startup sequence, an auxiliary
winding is supposed to take over the controller supply
voltage. To the opposite, for applications where the
resonant controller is powered from a standby power
supply, the startup level of the NCP1395B of 10 V typically
allows a direct a connection from a 12 V source. Simple
ON/OFF operation is therefore feasible.
ORDERING INFORMATION
Device Package Shipping
NCP1395APG PDIP16
(PbFree)
25 Units / Rail
NCP1395ADR2G SOIC16
(PbFree)
2500 Tape & Reel
NCP1395BPG PDIP16
(PbFree)
25 Units / Rail
NCP1395BDR2G SOIC16
(PbFree)
2500 Tape & Reel
For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specification
Brochure, BRD8011/D.
NCP1395A/B
http://onsemi.com
26
PACKAGE DIMENSIONS
PDIP16
P SUFFIX
CASE 64808
ISSUE T
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEADS
WHEN FORMED PARALLEL.
4. DIMENSION B DOES NOT INCLUDE
MOLD FLASH.
5. ROUNDED CORNERS OPTIONAL.
A
B
FC
S
H
GD
J
L
M
16 PL
SEATING
18
916
K
PLANE
T
M
A
M
0.25 (0.010) T
DIM MIN MAX MIN MAX
MILLIMETERSINCHES
A0.740 0.770 18.80 19.55
B0.250 0.270 6.35 6.85
C0.145 0.175 3.69 4.44
D0.015 0.021 0.39 0.53
F0.040 0.70 1.02 1.77
G0.100 BSC 2.54 BSC
H0.050 BSC 1.27 BSC
J0.008 0.015 0.21 0.38
K0.110 0.130 2.80 3.30
L0.295 0.305 7.50 7.74
M0 10 0 10
S0.020 0.040 0.51 1.01
____
NCP1395A/B
http://onsemi.com
27
SOIC16
CASE 751B05
ISSUE K
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER
SIDE.
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR PROTRUSION
SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D
DIMENSION AT MAXIMUM MATERIAL CONDITION.
18
16 9
SEATING
PLANE
F
J
M
RX 45_
G
8 PLP
B
A
M
0.25 (0.010) B S
T
D
K
C
16 PL
S
B
M
0.25 (0.010) A S
T
DIM MIN MAX MIN MAX
INCHESMILLIMETERS
A9.80 10.00 0.386 0.393
B3.80 4.00 0.150 0.157
C1.35 1.75 0.054 0.068
D0.35 0.49 0.014 0.019
F0.40 1.25 0.016 0.049
G1.27 BSC 0.050 BSC
J0.19 0.25 0.008 0.009
K0.10 0.25 0.004 0.009
M0 7 0 7
P5.80 6.20 0.229 0.244
R0.25 0.50 0.010 0.019
____
6.40
16X
0.58
16X 1.12
1.27
DIMENSIONS: MILLIMETERS
1
PITCH
SOLDERING FOOTPRINT*
16
89
8X
*For additional information on our PbFree strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice
to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any
liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental
damages. Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over
time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under
its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body,
or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death
may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees,
subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of
personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part.
SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
PUBLICATION ORDERING INFORMATION
N. American Technical Support: 8002829855 Toll Free
USA/Canada
Europe, Middle East and Africa Technical Support:
Phone: 421 33 790 2910
Japan Customer Focus Center
Phone: 81357733850
NCP1395/D
LITERATURE FULFILLMENT:
Literature Distribution Center for ON Semiconductor
P.O. Box 5163, Denver, Colorado 80217 USA
Phone: 3036752175 or 8003443860 Toll Free USA/Canada
Fax: 3036752176 or 8003443867 Toll Free USA/Canada
Email: orderlit@onsemi.com
ON Semiconductor Website: www.onsemi.com
Order Literature: http://www.onsemi.com/orderlit
For additional information, please contact your loc
a
Sales Representative