General Description
The Himalaya series of voltage regulator ICs and
power modules enable cooler, smaller, and simpler
power supply solutions. The MAXM17516 is a fixed-
frequency, step-down power module in a thermally-
efficient system-in-package (SiP) package that operates
from a 2.4V to 5.5V input supply voltage and supports
output currents up to 6A. The device includes a switch-
mode power-supply controller, dual n-channel MOSFET
power switches, a fully-shielded inductor, as well as
compensation components. The device supports 0.75V
to 1.8V programmable output voltage. The high level
of integration significantly reduces design complexity,
manufacturing risks, and offers a true plug-and-play
power-supply solution, reducing the time to market.
The MAXM17516 is available in a thermally-enhanced,
compact 28-pin, 10mm x 6.5mm x 2.8mm SiP and can
operate over the -40°C to +125°C industrial temperature
range.
Applications
● FPGAandDSPPoint-of-LoadRegulator
● BaseStationPoint-of-LoadRegulator
● IndustrialControlEquipment
● Servers
● ATEEquipment
● MedicalEquipment
Benets and Features
● ReducesDesignComplexity,ManufacturingRisks,
and Time-to-Market
• CompleteIntegratedStep-DownPowerSupplyina
Single Package
●SavesBoardSpaceinSpace-ConstrainedApplications
• Small Form Factor 6.5mm x 10mm x 2.8mm SiP
Package
• SimpliedPCBDesignwithasFewasFour
External Components
● OffersFlexibilityforPower-DesignOptimization
• 2.4Vto5.5VInputVoltageRange
• 0.75V to 1.8V Programmable Output Voltage
• 6A Output Current
• Fixed1MHzSwitchingFrequency
• Enable Input
• Power-GoodOutput
● ReducesPowerDissipation
• Upto94%Efciency
• Autoswitch,Light-Load,Pulse-SkippingMode
• High Impedance Shutdown
• <1μAShutdownCurrent
● OperatesReliablyandReducesSystemDowntime
• Voltage-Controlled Internal Soft-Start
• Fault Protection
• Output Undervoltage/Overvoltage Protection
• Thermal-Fault Protection
• PeakCurrentLimit
• -40°C to +125°C Operation
Ordering Information appears at end of data sheet.
IN
IN
IN
IN
V
CC
EN
GND GND GND
POK
FB
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
PGND
MAXM17516
V
IN
5V
V
OUT
1.1V, 6A
V
CC
2.2µF
(OPTIONAL )
22µF
22.1kΩ
PGND
PGND
PGND
PGND
PGND
PGND
47.5kΩ
270µF
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efficiency Power Module
19-7427; Rev 1; 4/15
Typical Application Circuit
EVALUATION KIT AVAILABLE
INtoPGND .............................................................-0.3V to +6V
VCCtoGND ............................................................-0.3V to +6V
VCC to IN ................................................................. -0.3V to +6V
ENtoGND ..............................................................-0.3V to +6V
FB,POKtoGND ...................................... -0.3V to (VCC + 0.3V)
OUT,EP3toGND ......................................-0.6V to (VIN + 0.3V)
PGNDtoGND ......................................................-0.3V to +0.3V
EP1toGND..........................................................-0.3V to +0.3V
EP2toPGND ......................................... -0.3V to + (VIN + 0.3V)
EP2toGND............................................ -0.6V to + (VIN + 0.3V)
ContinuousPowerDissipation(TA = +70°C)
28-Pin SIP (derate 37mW/°C above +70°C) ............2000mW
OperatingTemperatureRange ......................... -40°C to +125°C
Junction Temperature ...................................................... +125°C
StorageTemperatureRange ............................ -55°C to +150°C
LeadTemperature(soldering,10s) .................................+245°C
SiP
Junction-to-AmbientThermalResistance(qJA)...........25°C/W
Junction-to-CaseThermalResistance(qJC) .................6°C/W
(Note 1)
(VIN = VCC = VEN = 5V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.
See Typical Application Circuit.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
INPUT SUPPLY (VIN)
INInputVoltageRange VIN
2.4 5.5 V
VIN = VCC 4.5 5.5
IN Undervoltage Threshold Risingedge(100mVhysteresis) 2.05 2.19 2.4 V
IN Standby Supply Current IQVIN = VCC = 4.5V, no load 1 5.5 μA
VCC SUPPLY
VCCInputVoltageRange VCC 4.5 5.5 V
VCC Undervoltage Threshold Risingedge(160mVhysteresis) 3.9 4.2 4.5 V
VCC Shutdown Supply Current IVCC_SHD EN=GND,POKunconnected,measured
at VCC, TA = +25°C 0.1 1.0 μA
VCC Supply Current IVCC Regulatorenabled,noload,noswitching
(VFB = 1V) 62 135 μA
OUTPUT
Output Voltage Programmable
Range VOUT VIN = VCC = 5.2V, ILOAD = 2A
(see derating curve) 0.754 1.8 V
UnityGainOutput-Voltage
Tolerance/FBaccuracy FB=OUT,noload 0.757 0.765 0.783 V
FBLoadRegulationAccuracy
(RDROOP) 2A < IOUT<5A,FB=OUT -7.5 -4.4 -1 mV/A
FBLineRegulationAccuracy FB=OUT,noload,2.4V<VIN < 5.5V 1.253 4.5 mV/V
FBInputBiasCurrent TA = -40°C to +125°C (Note 3) -0.1 -0.015 +0.1 μA
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
2
Note 1: PackagethermalresistanceswereobtainedusingthemethoddescribedinJEDECspecificationJESD51-7,usingafour-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Absolute Maximum Ratings
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Package Thermal Characteristics
Electrical Characteristics
(VIN = VCC = VEN = 5V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.
See Typical Application Circuit.) (Note 2)
Note 2: Limitsare100%testedatTA =+25°C.Maximumandminimumlimitsareguaranteedbydesignandcharacterizationover
temperature.
Note 3: DesignguaranteedbyATEcharacterization.Limitsarenotproductiontested.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
AverageOutputCurrentLimit VIN = 5V 6 9 A
EFFICIENCY
Efciency VIN = 5V, VOUT = 1.1V, IOUT = 2A 86 %
VIN = 5V, VOUT = 1.1V, IOUT = 6A 74
SWITCHING FREQUENCY
Switching Frequency fSW 0.9 11.1 MHz
SOFT-START
Soft-StartRampTime tSS 1.79 ms
Soft-StartFaultBlankingTime tSSLT 3 ms
POWER-GOOD OUTPUT (POK)
POKUpperTripThresholdand
Overvoltage-Fault Threshold Risingedge,50mVhysteresis 830 850 870 mV
POKLowerTripThreshold Falling edge, 50mV hysteresis 658 690 725 mV
POKLeakageCurrent IPOK TA = +25°C, VPOK = 5.5V 0.1 1 μA
POKPropagationDelayTime tPOK FBforced50mVbeyondPOKtripthreshold 2μs
POKOutputLowVoltage ISINK = 3mA 100 mV
OvervoltageFaultLatchDelay
Time
FBforced50mVabovePOKupper-trip
threshold 2μs
UndervoltageFaultLatchDelay
Time
FBforced50mVbelowPOKlower-trip
threshold, TUV 1.6 ms
LOGIC INPUTS
EN Input High Threshold Rising,hysteresis=215mV(typ) 1.0 1.4 1.6 V
ENInputLeakageCurrent TA = +25°C 0.1 1 μA
THERMAL SHUTDOWN
Thermal-Shutdown Threshold TSHDN Hysteresis = 15°C +160 °C
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
3
Electrical Characteristics (continued)
(VCC = 5V, VIN = 3.3V - 5V, VOUT = 0.9V - 1.8V, IOUT = 0–6A, TA = +25°C, unless otherwise noted.)
60
65
70
75
80
85
90
95
100
100 1000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
EFFICIENCY
vs OUTPUT CURRENT
toc01
VIN = 3.3V
VCC = 5.0V
VOUT = 0.9V
VOUT = 1.2V
VOUT = 1.8V
60
65
70
75
80
85
90
95
100
100 1000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
EFFICIENCY
vs OUTPUT CURRENT
toc02
VIN = 5.0V
VCC = 5.0V
VOUT = 0.9V
VOUT = 1.2V
VOUT = 1.8V
0.740
0.745
0.750
0.755
0.760
0.765
0.770
0.775
0.780
0.0 1.0 2.0 3.0 4.0 5.0 6.0
VOUT (V)
OUTPUT CURRENT (A)
LOAD REGULATION
VOUT = 0.75V
toc03
VOUT = 0.75V
VCC = 5.0V
VIN = 3.3V
VIN = 5.0V
1.140
1.150
1.160
1.170
1.180
1.190
1.200
1.210
0.0 1.0 2.0 3.0 4.0 5.0 6.0
V
OUT
(V)
OUTPUT CURRENT (A)
LOAD REGULATION
VOUT = 1.2V
toc04
VOUT = 1.2V
VCC = 5.0V
VIN = 3.3V
VIN = 5.0V
1.720
1.730
1.740
1.750
1.760
1.770
1.780
1.790
1.800
1.810
1.820
1.830
0.0 1.0 2.0 3.0 4.0 5.0 6.0
V
OUT
(V)
OUTPUT CURRENT (A)
LOAD REGULATION
V
OUT
= 1.8V
toc05
V
OUT
= 1.8V
V
CC
= 5.0V
V
IN
= 5.0V
OUTPUT VOLTAGE RIPPLE
VIN = 5V, VOUT = 1.2V, IOUT = 6A
20mV/div
(AC-
COUPLED)
toc06
1µs/div
VOUT
INPUT VOLTAGE RIPPLE
VIN = 5V, VOUT = 1.2V, IOUT = 6A
100mV/div
(AC-
COUPLED)
toc07
1µs/div
VIN
LOAD CURRENT TRANSIENT RESPONSE
VIN = 3.3V, VOUT = 1.2V, IOUT= 3 - 6A
2A/div
toc08
10us/div
IOUT
VOUT
50mV/div
(AC
COUPLED)
LOAD CURRENT TRANSIENT RESPONSE
VIN = 5.0V, VOUT = 1.2V, IOUT = 3 - 6A
2A/div
toc09
10µs/div
IOUT
VOUT
50mV/div
(AC
COUPLED)
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
Maxim Integrated
│
4
www.maximintegrated.com
Typical Operating Characteristics
(VCC = 5V, VIN = 3.3V - 5V, VOUT = 0.9V - 1.8V, IOUT = 0–6A, TA = +25°C, unless otherwise noted.)
LOAD CURRENT TRANSIENT RESPONSE
VIN = 5.0V, VOUT = 1.8V, IOUT = 3 - 6A
2A/div
toc10
10µs/div
IOUT
VOUT
50mV/div
(AC
COUPLED)
STARTUP WAVEFORM
VIN = 3.3V, VOUT = 1.2V, IOUT = 0A
500mV/div
toc11
400µs/div
IIN
VOUT
2V/div
VEN
VPOK
200mA/div
5V/div
SHUTDOWN WAVEFORM
VIN = 3.3V, VOUT = 1.2V, IOUT = 30mA
500mV/div
toc12
400µs/div
2V/div
200mA/div
5V/div
IIN
VOUT
VEN
VPOK
STARTUP WAVEFORM
VIN = 3.3V, VOUT = 1.2V, IOUT= 6A
500mV/div
toc13
400µs/div
2V/div
5A/div
5V/div
IIN
VOUT
VEN
VPOK
SHUTDOWN WAVEFORM
VIN = 3.3V, VOUT = 1.2V, IOUT = 6A
500mV/div
toc14
400µs/div
2V/div
5A/div
5V/div
IIN
VOUT
VEN
VPOK
STARTUP WAVEFORM
VIN = 5.0V, VOUT = 1.2V, IOUT = 0A
500mV/div
toc15
400µs/div
IIN
VOUT
2V/div
VEN
VPOK
200mA/div
5V/div
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
Maxim Integrated
│
5
www.maximintegrated.com
Typical Operating Characteristics (continued)
(VCC = 5V, VIN = 3.3V - 5V, VOUT = 0.9V - 1.8V, IOUT = 0–6A, TA = +25°C, unless otherwise noted.)
SHUTDOWN WAVEFORM
VIN = 5.0V, VOUT = 1.2V, IOUT =30mA
500mV/div
toc16
400µs/div
2V/div
200mA/div
5V/div
IIN
VOUT
VEN
VPOK
STARTUP WAVEFORM
VIN = 5.0V, VOUT = 1.2V, IOUT = 6A
500mV/div
toc17
400µs/div
2V/div
5A/div
5V/div
IIN
VOUT
VEN
VPOK
SHUTDOWN WAVEFORM
VIN = 5.0V, VOUT = 1.2V, IOUT = 6A
500mV/div
toc18
400µs/div
2V/div
5A/div
5V/div
IIN
VOUT
VEN
VPOK
LOAD SHORT CIRCUIT
VIN = 5.0V, VOUT = 1.2V, IOUT = 0A
1V/div
toc19
400µs/div
2V/div
2A/div
5A/div
IIN
VOUT
VPOK
IOUT
LOAD SHORT CIRCUIT
V
IN
= 5.0V, V
OUT
= 1.2V, I
OUT
= 6A
1V/div
toc20
400µs/div
2V/div
2A/div
5A/div
IIN
VOUT
VPOK
IOUT
0
1
2
3
4
5
6
7
50 60 70 80 90 100 110 120
OUTPUT CURRENT (A)
AMBIENT TEMPERATURE (°C)
OUTPUT CURRENT
vs. AMBIENT TEMPERATURE
V
IN
= 5V NO AIR FLOW
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
Maxim Integrated
│
6
www.maximintegrated.com
Typical Operating Characteristics (continued)
PIN NAME FUNCTION
1–3,
28 IN
InputSupplyConnection.BypasstoGNDwitha22µFor2x10µFceramiccapacitor.Supplyrangeforthis
pin is 4.5V to 5.5V. When VCC can be supplied separately from a 4.5V to 5.5V source, the IN pin can then be
powered from a 2.4V to 5.5V supply.
4POK Open-DrainPower-GoodOutput.POKispulledlowifFBismorethan12%(typ)aboveorbelowthenominal
regulationthreshold.POKisheldlowinshutdown.POKbecomeshighimpedancewhenFBisinregulation
range.Pullthispinupwith10kΩ(typ)resistorvalue.
5–7 GND GND.ConnectPGNDandGNDtogetheratasinglepoint.
8 VCC
5VBiasSupplyInputfortheInternalSwitchingRegulatorDrivers.ForINfrom4.5Vto5.5V,VCC can be
connected to the IN supply. For IN supply voltages lower than the above range, VCC should be powered from
aseparate5V±10%supplyandbypassedwitha1µForgreaterceramiccapacitor.
9FB FeedbackInputfortheInternalStep-DownConverter.ConnectFBtoaresistivedividerbetweenOUTand
GNDtoadjustthetypicaloutputvoltagebetween0.765Vto1.8V.Keepequivalentdividerresistancelower
than50kΩ.
10 EN RegulatorEnableInput.WhenENispulledlow,theregulatorisdisabled.WhenENisdrivenhigh,the
regulator is enabled.
11, 12 N.C. No Connection
13–20 OUT RegulatorOutputPins.ConnectanoutputcapacitorbetweenOUTandPGNDwitha220µF(typ)POSCAP
low-ESRcapacitor.
21–27 PGND PowerGNDReturn.ConnecttoGND.
— EP1 ExposedPad1.ConnectthispadtothePGNDgroundplaneof1inby1incopperforcooling.
— EP2 ExposedPad2.ConnectthispadtothePCBforbetterthermalperformance,butdonotconnecttoanyothernode.
Minimizeareaofcopperisland.
— EP3 Exposed Pad 3. Connect this pad to the OUT pins and the copper area of 1in by 1in.
56 7 8 9 10 11 12 13 14
POK
GND
GND
GND
V
C C
FB
E N
N.C.
N.C.
O U T
O U T
OUT
OUT
OUT
OUT
O U T
O U T
PGND
PGND
PGND
PGND
PGND
PGND
PGND
I N
19
2021
22
23
242526
27
28
415
IN
IN
IN
1
2
3
16
17
18
MAXM17516
EP 2
EP 1 EP 3
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
7
Pin Description
Pin Conguration
OUT
IN
PGND
FB
POK
EN
VCC
GND
1µH
2.2µF
2.2µF
0.1µF
MAXM17516
POK
LOGIC
CURRENTMODE
CONTROLLER
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
8
Functional Diagram
Design Procedure
Adjusting Output Voltage
TheMAXM17516producesanadjustable0.75Vto1.8V
output voltage from a 2.4V to 5.5V input voltage range by
usingaresistivefeedbackdividerfromOUTtoFB.
Adjustingtheoutputvoltageofthedevicerequiresaresis-
tive divider network from OUT to FB, according to the
equation below. From the initial output voltage, the load-
line regulation reduces the effective feedback voltage by
a typical 5mV/A as the output current increases.
OUT
UB
V
RR 1
0.765

=×−


kΩ,whereRBisinkΩ.
Input Voltage Range
The maximum value (VIN(MAX)) and minimum value
(VIN(MIN)) must accommodate the worst-case conditions
accounting for the input voltage soars and drops. If there
is a choice at all, lower input voltages result in better
efficiency. With a maximum duty cycle of 87.5%, VOUT
is limited to 0.875 x VIN. To operate with a 6A output
current, the minimum input voltage given an output
voltage is shown in Figure 1.
Input Capacitor Selection
The input capacitor must meet the ripple-current requirement
(IRMS) imposed by the switching currents. The IRMS
requirements of the regulator can be determined by the
following equation:
RMS OUT
I I D (1 D)= × ×−
The worst-case RMS current requirement occurs when
operatingwithD=0.5.Atthispoint,theaboveequation
simplifies to IRMS = 0.5 x IOUT.
The minimum input capacitor required can be calculated
by the following equation:
( )
( )
IN_AVG
IN
IN SW
I (1 D)
CVf
×−
=∆×
where,
IIN_AVGis the average input current given by:
OUT
IN_ Avg IN
P
IV
=η×
D is the operating duty cycle, which is approximately
equal to VOUT/VIN where:
∆VIN is the required input-voltage ripple,
fSW is the operating switching frequency,
POUT is the output power, which is equal to VOUT x IOUT,
ηistheefficiency.
For the device’s system (IN) supply, ceramic capacitors
are preferred due to their resilience to inrush surge
currents typical of systems, and due to their low parasitic
inductance, which helps reduce the high-frequency ringing
on the IN supply when the internal MOSFETs are turned
off. Choose an input capacitor that exhibits less than
+10°CtemperatureriseattheRMSinputcurrentforoptimal
circuit longevity.
Figure 1. Minimum VIN Figure 2. Adjusting Output Voltage
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0.5 1.0 1.5 2.0
VIN_MIN (V)
OUTPUT VOLTAGE (V)
MINIMUM VIN
IOUT = 6A
OUT
MAXM17516
V
OUT
FB
R
U
R
B
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
9
Output Capacitor Selection
The output capacitor selection requires careful evalua-
tion of several different design requirements (e.g., stability,
transient response, and output ripple voltage) that place
limits on the output capacitance and the effective series
resistance (ESR). Based on these requirements, a
combination of low-ESR polymer capacitors (lower cost
but higher output ripple voltage) and ceramic capacitors
(higher cost but low output ripple voltage) should be used
to achieve stability with low output ripple.
Loop Compensation
The gain portion of the loop gain is a result of error-
amplifier gain, current-sensing gain, and load with an
overall typical value at 1kHz of 36dB at VIN = 5V, and
46dBatVIN = 3V, with a typical limit to the gain-bandwidth
(GBW)productof120,000.Thecrossovershouldoccur
before this error-amplifier bandwidth limit of 120kHz
(gain = 1). The output capacitor and load introduces a
pole with the worst case at the maximum load (6A). If
the load pole location is further than a frequency where
thegainexceedstheGBW,thegaindropstartsearlierat
the location where the loop gain is limited. This situation
applies typically to an output voltage less than 1.8V, so
zerofrequencyfromtheESRisneededtoincreasethe
phase margin at the crossover frequency.
The recommended relationship between ESR and total
output capacitance values are shown in Table 1. When a
low-ESRtypecapacitorisusedwithaceramiccapacitor,
arecommendedvalueof44µFto100µFceramiccapacitor
should be used to make up the total capacitance value
with the relationship between ESR and total output
capacitance value, such that the zero frequency is
between32kHzand40kHz.Whenonlyalow-ESRtype
capacitorisused,thezerofrequencyshouldbebetween
62kHzand80kHz.Optionally,asmall10µF–22µFceramic
capacitor can be used to reduce output ripple.
Optionally, for an output greater than or equal to 1.8V,
an all-ceramic capacitor solution can be used with a
minimum capacitance value that locates the pole location
below1kHzwithresistiveload(6A),andwithasimplified
equation given by COUTMIN(µF)=900/VOUT.
Output Ripple Voltage
Withpolymercapacitors,theESRdominatesanddeter-
mines the output ripple voltage. The step-down regulator’s
output ripple voltage (VRIPPLE) equals the total inductor
ripple current (ΔIL) multiplied by the output capacitor’s
ESR. Therefore, the maximum ESR to meet the output
ripple-voltage requirement is:
RIPPLE
ESR L
V
RI
≤∆
where,
IN OUT OUT
L
IN SW
VV V 1
IL Vf

−

∆= × ×




where, fSWistheswitchingfrequencyandListheinductor
(1µH).
The actual capacitance value required relates to the
physicalcasesizeneededtoachievetheESRrequirement,
as well as to the capacitor chemistry. Thus, polymer
capacitorselectionisusuallylimitedbyESRandvoltage
rating rather than by capacitance value.
With ceramic capacitors, the ripple voltage due to capaci-
tance dominates the output ripple voltage. Therefore,
the minimum capacitance needed with ceramic output
capacitors is:
OUT
SW
L
RIPPLE
I1
C
8f V

∆
= ×

×

Alternatively,combiningceramics(forthelowESR)and
polymers (for the bulk capacitance) helps balance the output
capacitance vs. output ripple-voltage requirements.
Table 1. Output Capacitor Selection vs. ESR
TOTAL COUT (µF) LOW-ESR TYPE WITH CERAMIC-TYPE
ESR (mΩ)
LOW-ESR TYPE WITHOUT CERAMIC-TYPE
ESR (mΩ)
250 16–20 8–10
300 13–17 7–9
350 11–14 6, 7
400 10–12 5, 6
450 9–11 4–6
500 8–10 4, 5
550 7–9 4, 5
600 7, 8 3, 4
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
10
Idle Mode is a trademark of Maxim Integrated Products, Inc
Load-Transient Response
The load-transient response depends on the overall output
impedance over frequency, and the overall amplitude
and slew rate of the load step. In applications with large,
fast-load transients (load step > 80% of full load and slew
rate > 10A/μs), the output capacitor’s high-frequency
response (ESL and ESR) needs to be considered. To
prevent the output voltage from spiking too low under a
load-transientevent,theESRislimitedbythefollowing
equation (ignoring the sag due to finite capacitance):
RIPPLESTEP
ESR
OUTSTEP
V
RI
≤∆
where, VRIPPLESTEP is the allowed voltage drop during
load current transient, and IOUTSTEP is the maximum
load current step.
The capacitance value dominates the mid-frequency
output impedance and continues to dominate the load-
transient response as long as the load transient’s slew
rate is fewer than two switching cycles. Under these
conditions, the sag and soar voltages depend on the
output capacitance, inductance value, and delays in the
transientresponse.Lowinductorvaluesallowtheinductor
current to slew faster, replenishing charge removed from
or added to the output filter capacitors by a sudden load
step, especially with low differential voltages across the
inductor. The minimum capacitance needed to handle the
sag voltage (VSAG) that occurs after applying the load
current can be estimated by the following equation:
( )
( )
OUT_SAG SAG
2
STEP STEP sw
MAX
1
CV
L IOUT
1IOUT (t T)
2 VIN D VOUT
= ×


×∆


+ ∆ × −∆

×−



where:
D
MAX is the maximum duty factor (87.5%),
tSW is the switching period (1/fSW),
ΔT equals VOUT/VIN x tSW when in PWM mode, or
LxIIDLE/(VIN - VOUT) when in Idle Mode (1.5A).
The minimum capacitance needed to handle the overshoot
voltage (VSOAR) that occurs after load removal (due to
stored inductor energy) can be calculated as:
( )
2
STEP
OUT_SOAR OUT SOAR
IOUT L
C2V V
∆
≈
When the device is operating under low duty cycle,
the output capacitor size is usually determined by the
COUT_SOAR.
Detailed Description
The MAXM17516 is a complete step-down switch-mode
power-supply solution that can deliver up to 6A output
current and up to 1.8V output voltage from a 2.4V to 5.5V
input voltage range. The device includes switch-mode
power-supply controller, dual n-channel MOSFET power
switches, and an inductor. The device uses a fixed-
frequency current-mode control scheme.
The device provides peak current-limit protection, output
undervoltage protection, output overvoltage protection,
and thermal protection. The device operates in skip
mode at light loads to improve the light-load efficiency.
Independent enable and an open-drain power-good output
allow flexible system power sequencing. The fixed voltage
soft-start reduces the inrush current by gradually ramping
up the internal reference voltage.
Fixed-Frequency Current-Mode Controller
The heart of the current-mode PWM controller is a
multistage, open-loop comparator that compares the output
voltage-error signal with respect to the reference voltage,
the current-sense signal, and the slope-compensation
ramp (see the Functional Diagram). The device uses a
direct summing configuration, approaching ideal cycle-to-
cycle control over the output voltage without a traditional
error amplifier and the phase shift associated with it.
Light-Load Operation
The device features an inherent automatic switchover
to pulse skipping (PFM operation) at light loads. This
switchover is affected by a comparator that truncates
thelow-sideswitchon-timeattheinductorcurrent’szero
crossing.Thezero-crossingcomparatorsensestheinduc-
tor current during the off-time. Once the current through
thelow-sideMOSFETdropsbelowthezero-crossingtrip
level, it turns off the low-side MOSFET. This prevents the
inductor from discharging the output capacitors and forces
the switching regulator to skip pulses under light-load
conditions to avoid overcharging the output. Therefore,
the controller regulates the valley of the output ripple
under light-load conditions. The switching waveforms can
appear noisy and asynchronous at light-load pulse-skip-
ping operation, but this is a normal operating condition
that results in high light-load efficiency.
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
11
Idle Mode™ Current-Sense Threshold
In Idle Mode, the on-time of the step-down controller
terminates when both the output voltage exceeds the
feedback threshold, and the internal current-sense
voltage falls below the Idle Mode current-sense threshold
(IIDLE = 1.5A). Another on-time cannot be initiated until
the output voltage drops below the feedback threshold. In
this mode, the behavior appears like PWM operation with
occasional pulse skipping, where inductor current does
not need to reach the light-load level.
Power-On Reset (POR) and UVLO
Power-on reset (POR) occurs when VCC rises above
approximately 2.1V, resetting the undervoltage, over-
voltage, and thermal-shutdown fault latches. The VCC
inputundervoltage-lockout(UVLO)circuitrypreventsthe
switching regulators from operating if the 5V bias supply
(VCC)isbelowits4VUVLOthreshold.
Soft-Start
The internal step-down controller starts switching and
the output voltage ramps up using soft-start. If the VCC
biassupplyvoltagedropsbelowtheUVLOthreshold,the
controller stops switching and disables the drivers (LX
becomes high impedance) until the bias supply voltage
recovers.
Once the 5V VCC bias supply and VIN rise above their
respectiveinputUVLOthresholds,andENispulledhigh,
the internal step-down controller becomes enabled and
begins switching. The internal voltage soft-starts gradually
increment the feedback voltage by approximately 25mV
every 61 switching cycles, making the output voltage
reach its nominal regulation voltage 1.79ms after the
regulator is enabled (see the Soft-Start Waveforms in the
Typical Operating Characteristics section).
Power-Good Output (POK)
POKistheopen-drainoutputofthewindowcomparator
that continuously monitors the output for undervoltage
and overvoltage conditions. POK is actively held low in
shutdown (EN = GND). POK becomes high impedance
after the device is enabled and the output remains within
±10%ofthenominalregulationvoltagesetbyFB.POK
goes low once the output drops 12% (typ) below or rises
12% (typ) above its nominal regulation point, or the output
shuts down. For a logic-level POK output voltage, con-
nectanexternalpullupresistorbetweenPOKandVCC. A
10kΩpullupresistorworkswellinmostapplications.
Output Overvoltage Protection (OVP)
If the output voltage rises to 112% (typ) of its nominal
regulation voltage, the controller sets the fault latch, pulls
POK low, shuts down the regulator, and immediately
pulls the output to ground through its low-side MOSFET.
Turning on the low-side MOSFET with 100% duty cycle
rapidly discharges the output capacitors and clamps the
output to ground. However, this commonly undamped
response causes negative output voltages due to the
energystoredintheoutputLCattheinstantof0Vfault.If
the load cannot tolerate a negative voltage, place a power
Schottky diode across the output to act as a reverse-
polarity clamp. If the condition that caused the overvolt-
age persists (such as a shorted high-side MOSFET),
the input source also fails (short-circuit fault). Cycle VCC
below 1V or toggle the enable input to clear the fault latch
and restart the regulator.
Output Undervoltage Protection (UVP)
The device includes an output undervoltage-protection
(UVP) circuit that begins to monitor the output once the
startup blanking period has ended. If the output voltage
drops below 88% (typ) of its nominal regulation voltage,
the regulator pulls the POK output low and begins the
UVP fault timer. Once the timer expires after 1.6ms, the
regulator shuts down, forcing the high-side MOSFET
off and disabling the low-side MOSFET once the zero-
crossing threshold has been reached. Cycle VCC below
1V, or toggle the enable input to clear the fault latch and
restart the regulator.
Thermal-Fault Protection
The device features a thermal-fault protection circuit.
Whenthejunctiontemperaturerisesabove+160°C(typ),
a thermal sensor activates the fault latch, pulls down the
POKoutput,andshutsdowntheregulator.ToggleENto
clear the fault latch, and restart the controllers after the
junctiontemperaturecoolsby15°C(typ).
Power Dissipation
The device output current needs to be derated if the
device needs to operate in high ambient temperature. The
amount of current derating depends upon the input voltage,
output voltage, and ambient temperature. The derating
curves given in the Typical Operating Characteristics
section can be used as a guide.
The maximum allowable power losses can be calculated
using the following equation:
JMAX A
MAX JA
TT
PD
−
=q
where:
PDMAX is the maximum allowed power losses with
maximumallowedjunctiontemperature,
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
12
TJMAXisthemaximumallowedjunctiontemperature,
TA is operating ambient temperature,
qJAisthejunction-to-ambientthermalresistance.
PCB Layout Guidelines
CarefulPCBlayoutiscriticaltoachievinglowswitching
losses and clean, stable operation. Use the following
guidelinesforgoodPCBlayout:
● Keeptheinputcapacitorsascloseaspossibletothe
INandPGNDpins.
● Keeptheoutputcapacitorsascloseaspossibleto
theOUTandPGNDpins.
● ConnectallthePGNDconnectionstoaslargea
copper plane area as possible on the top layer.
● ConnectEP1tothePGNDandGNDplanesonthe
top layer.
● UsemultipleviastoconnectinternalPGNDplanesto
thetop-layerPGNDplane.
● DonotkeepanysoldermaskonEP1–EP3on
bottomlayer.Keepingsoldermaskonexposedpads
decreases the heat-dissipating capability.
● Keepthepowertracesandloadconnectionsshort.
This practice is essential for high efficiency. Using
thickcopperPCBs(2ozvs.1oz)canenhancefull-
loadefficiency.CorrectlyroutingPCBtracesisa
difficult task that must be approached in terms of
fractions of centimeters, where a single milliohm of
excess trace resistance causes a measurable
efficiency penalty.
Figure 3. Layout Recommendation
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
PART TEMP RANGE MSL PIN-PACKAGE
MAXM17516ALI+T -40°C to +125°C 3 28 SiP PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
28 SiP L286510+1 21-0701 90-0445
V
OUT
56 7 8 10 11 12 13 14
2021
22
23
242526
27
28
415
1
2
316
17
18
EP2EP1 EP3
V
V
OUT
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
www.maximintegrated.com Maxim Integrated
│
13
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
thata“+”,“#”,or“-”inthepackagecodeindicatesRoHSstatus
only. Package drawings may show a different suffix character, but
thedrawingpertainstothepackageregardlessofRoHSstatus.
Chip Information
PROCESS:BiCMOS
Ordering Information
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 12/14 Initial release —
1 4/15 TightenedFBaccuracyandaddedMSL3rating 2, 13
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAXM17516 6A, 2.4V to 5.5V Input,
High-Efciency Power Module
© 2015 Maxim Integrated Products, Inc.
│
14
Revision History
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.