19-7543; Rev 3; 7/16
Ordering Information appears at end of data sheet.
General Description
The MAX17620 is a high-frequency, high-efficiency
synchronous step-down DC-DC converter with integrated
MOSFETs that operates over a 2.7V to 5.5V input voltage
range. The device supports up to 600mA load current and
1.5V to 100% VIN output voltage. High-frequency operation
enables the use of small, low-cost inductors and capacitors.
The device features selectable PWM/skip mode of
operation at light loads and operates at a 4MHz fixed-
frequency in PWM mode. Skip mode improves system
efficiency at light loads, while PWM mode maintains a
constant switching frequency over the entire load.
In skip mode, the device draws only 40µA of quiescent
current from the supply input. In shutdown mode, the current
consumption is reduced to 0.1µA.
The device also features a soft-start feature to reduce
the inrush current during startup, and also incorporates an
enable (EN) pin to turn on/off the device. An open-drain
PGOOD pin provides power-good signal to the system
upon achieving successful regulation of the output voltage.
The MAX17620 is available in an 8-pin, 2mm x 2mm
TDFN package and operates over the -40°C to +125°C
temperature range.
Applications
●Point-of-Load Power Supply
●Standard 5V Rail Supplies
●Battery-Powered Instruments
●Distributed Power Systems
Benets and Features
●Minimizes External Components, Reducing Total
Cost
• Synchronous Operation for High Efciency and
Reduced Cost
• Internal Compensation for Stable Operation at Any
Output Voltage
• All-Ceramic Capacitor Solution
• 4MHz Operation
• Only 5 External Components Required
• Total Solution Size is 12mm2 (Sum of the
Components Area)
●Reduces Number of DC-DC Regulators to Stock
• Wide 2.7V to 5.5V Input Voltage Range
• Adjustable 1.5V to 100% VIN Output Voltage Range
• Delivers Up to 600mA Load Current
• 100% Duty-Cycle Operation
• +1%/-0.75% Reference Voltage Accuracy
• Available in a 2mm x 2mm TDFN Package
●Reduces Power Dissipation
• Peak Efciency 91%
• Skip Mode for High Light-Load Efciency
• Shutdown Current = 0.1µA
●Operates Reliably
• Peak Current-Limit Protection
• Soft-Start Reduces Inrush Current During Startup
• Built-In Output-Voltage Monitoring
(Open-Drain PGOOD Pin)
• -40°C to +125°C Operation
Typical Application Circuit—1.8V, 600mA Step-Down Regulator
LX
V
OUT
FB
GND
MODE
IN
PGOOD
EN
2.7V TO 5.5V
R1
24kΩ
V
OUT
1.8V/600mA
C
IN
2.2µF
L
1µH
MAX17620
C
IN
: 2.2µF/10V/0603/X7R,GRM188R71A225KE15D, MUR
ATA
L1: 1μH, 60mΩ, MAKK2016H1ROM, TAIYO-YUDEN
C
OUT
:10μF/6.3V/0805/X7R, GRM21BR70J106KE76K, MURATA
C
OUT
10µF
R2
19.1kΩ
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
IN to GND .................................................................. -0.3V to 6V
LX to GND .................................................................-0.3V to 6V
MODE .......................................................... -0.3V to VIN + 0.3V
EN, PGOOD, FB, VOUT to GND ..............................-0.3V to 6V
Continuous Power Dissipation (up to TA = +70°C)
(derate 9.8mW/°C above TA = +70°C) .........................784.3mW
Operating Temperature Range ......................... -40°C to +125°C
Junction Temperature ...................................................... +150°C
Storage Temperature Range ............................ -65°C to +150°C
Soldering Temperature (Reflow) ......................................+260°C
(Note 1)
TDFN
Junction-to-Ambient Thermal Resistance (θJA) ........102°C/W Junction-to-Case Thermal Resistance (θJC) .................8°C/W
Electrical Characteristics
VIN = +3.6V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical specifications are at TA = TJ = +25°C. (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
INPUT SUPPLY (IN)
Input Voltage Range VIN 2.7 5.5 V
Input Supply Current
IIN-SH VEN = 0V, shutdown mode 0.1 µA
IQ_SKIP Nonswitching 40
IQ-PWM PWM mode (switching) 6 mA
Undervoltage-Lockout Threshold
(UVLO) VIN_UVLO VIN rising 2.55 2.6 2.65 V
UVLO Hysteresis VIN_UVLO_HYS 200 mV
ENABLE (EN)
EN Low Threshold VEN_LOW VEN falling 0.8 V
EN High Threshold VEN_HIGH VEN rising 2 V
EN Hysteresis VEN_HYS 220 mV
EN Input Leakage IEN VEN = 5.5V, TA = TJ = +25°C 10 50 nA
POWER MOSFETS
High-Side pMOS On-Resistance RDS-ONH VIN = 3.6V, ILX = 190mA 120 200 mΩ
High-Side pMOS On-Resistance RDS-ONH VIN = 5.0V, ILX = 190mA 100 160 mΩ
Low-Side nMOS On-Resistance RDS-ONL VIN = 3.6V, ILX = 190mA 80 145 mΩ
Low-Side nMOS On-Resistance RDS-ONL VIN = 5.0V, ILX = 190mA 70 130 mΩ
LX Leakage Current ILX_LKG LX = GND or IN, TA = +25°C 0.1 1 µA
High-Side Peak Current Limit ILIM_PEAK 1150 1450 1800 mA
Low-Side Valley Current Limit ILIM_VALLEY 920 1170 1450 mA
Low-Side Negative Current Limit ILIM_NEG Current entering into LX pin 1050 mA
Low-Side Zero-Crossing
Current Limit ILIM_ZX
MODE = IN, current leaving out of LX
pin 100 mA
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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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 (continued)
VIN = +3.6V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical specifications are at TA = TJ = +25°C. (Note 2)
Note 2: Limits are 100% production tested at TA = +25°C. Limits over the operating temperature range and relevant supply voltage
range are guaranteed by design and characterization.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SWITCHING FREQUENCY
Switching Frequency fSW MODE = GND 3.84 4 4.16 MHz
Minimum Controllable On-Time tON_MIN 40 ns
LX Dead Time 3 ns
Soft-Start Time tSS tSS = 4096 CLK cycles 1 ms
FEEDBACK (FB)
FB Voltage Accuracy VFB PWM mode -0.75 +1 %
FB Input Bias Current IFB FB = 0.6V, TA = TJ = 25°C 50 120 nA
POWER GOOD (PGOOD)
PGOOD Rising Threshold FB rising 91.5 93.5 95.5 %
PGOOD Falling Threshold FB falling 88 90 92 %
PGOOD Output Low IPGOOD = 5mA 200 mV
PGOOD Output Leakage Current IPGOOD_LKG PGOOD = 5.5V, TA = TJ = 25°C 100 nA
MODE
MODE Pullup Current VMODE = GND 5 µA
THERMAL SHUTDOWN
Thermal-Shutdown Rising
Threshold Temperature rising 165 °C
Thermal-Shutdown Hysteresis 10 °C
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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(See the Typical Application Circuits, TA = +25°C, VIN = 3.6V, unless otherwise noted.)
60
65
70
75
80
85
90
95
100
50 150 250 350 450 550
EFFICIENCY(%)
LOAD CURRENT (mA)
1.8V OUTPUT, PWM MODE,
EFFICIENCY vs. LOAD CURRENT
V
IN
= 5.5V
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 2.7V
MODE = GND
1.790
1.795
1.800
1.805
1.810
1.815
1.820
1.825
1.830
0 100 200 300 400 500 600
OUTPUT VOLTAGE (V)
LOAD CURRENT (mA)
1.8V OUTPUT, SKIP MODE,
LOAD AND LINE REGULATION
V
IN
= 3.6V
V
IN
= 2.7V
V
IN
= 5.5V
V
IN
= 4.2V
MODE = OPEN
70
75
80
85
90
95
100
1 10 100
EFFICIENCY(%)
LOAD CURRENT (mA)
1.8V OUTPUT, SKIP MODE,
EFFICIENCY vs. LOAD CURRENT
VIN = 5.5V
VIN = 4.2V
VIN = 3.6V
VIN = 2.7V
MODE = OPEN
600
790
792
794
796
798
800
802
804
806
808
810
-40 -20 020 40 60 80 100 120
FEEDBACK VOLTAGE (V)
TEMPERATURE (°C)
FEEDBACK VOLTAGE vs. TEMPERATURE
1.790
1.795
1.800
1.805
1.810
0 100 200 300 400 500 600
OUTPUT VOLTAGE (V)
LOAD CURRENT (mA)
1.8V OUTPUT, PWM MODE,
LOAD AND LINE REGULATION
VIN = 4.2V
VIN = 5.5V
VIN = 3.6V
VIN = 2.7V
MODE = GND
30
35
40
45
50
55
60
-40 -20 020 40 60 80 100 120
INPUT SUPPLY CURRENT (µA)
TEMPERATURE (°C)
INPUT SUPPLY CURRENT vs.
TEMPERATURE, SKIP MODE
VIN = 2.7V
VIN = 3.6V
VIN = 5.5V
-10
0
10
20
30
40
50
60
70
-40 -20 020 40 60 80 100 120
SHUTDOWN CURRENT (nA)
TEMPERATURE (°C)
SHUTDOWN CURRENT vs. TEMPERATURE
VIN = 2.7V
VIN = 3.6V
VIN = 5.5V
200mA/div
200μs/div
VEN 5V/div
SOFT-START FROM EN, PWM MODE,
1.8V OUTPUT, NO LOAD CURRENT
VOUT
IOUT
1V/div
2V/div
VPGOOD
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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Typical Operating Characteristics
(See the Typical Application Circuits, TA = +25°C, VIN = 3.6V, unless otherwise noted.)
200mA/div
1ms/div
VEN 5V/div
SOFT-START/SHUTDOWN FROM EN,
1.8V OUTPUT, 600mA LOAD CURRENT
VOUT
IIN
1V/div
2V/div
VPGOOD
100ns/div
VL
ILX
X
10mV/div
STEADY-STATE SWITCHING WAVEFORMS,
1.8V OUTPUT, 600mA LOAD CURRENT
VOUT
(AC)
2V/div
500mA/div
200μs/div
VEN 5V/div
SOFT-START WITH 1V PREBIAS,
1.8V OUTPUT, PWM MODE
VOUT 1V/div
2V/div
VPGOOD
4µs/div
VLX
20mV/div
STEADY-STATE SWITCHING WAVEFORMS,
1.8V OUTPUT, 10mA LOAD, SKIP MODE
VOUT
(AC)
2V/div
500mA/div
ILX
100ns/div
VL
ILX
X
10mV/div
STEADY-STATE SWITCHING WAVEFORMS,
1.8V OUTPUT, NO LOAD, PWM MODE
VOUT
(AC)
2V/div
200mA/div
40μs/div
20mV/div
1.8V OUTPUT, PWM MODE,
(LOAD CURRENT STEPPED
FROM NO LOAD TO 300mA)
VOUT
(AC)
200mA/div
IOUT
40μs/div
20mV/div
1.8V OUTPUT,
(LOAD CURRENT STEPPED
FROM 300mA TO 600mA)
VOUT
(AC)
200mA/div
IOUT
40µs/div
50mV/div
1.8V OUTPUT, SKIP MODE,
(LOAD CURRENT STEPPED
FROM 5mA TO 300mA)
VOUT
(AC)
200mA/div
IOUT
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
Maxim Integrated
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Typical Operating Characteristics (continued)
40µs/div
20mV/div
1.8V OUTPUT, SKIP MODE,
(LOAD CURRENT STEPPED
FROM 5mA TO 50mA)
VOUT
(AC)
50mA/div
IOUT 500mA/div
400µs/div
VOUT 1V/div
OVERLOAD PROTECTION, 1.8V OUTPUT
IOUT
BODE PLOT
GAIN
TOC19
GAIN (dB)
FREQUENCY(Hz)
FCR =189KHz,
PHASE MARGIN = 62°
PHASE
GAIN
PHASE (º)
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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Typical Operating Characteristics (continued)
(See the Typical Application Circuits, TA = +25°C, VIN = 3.6V, unless otherwise noted.)
PIN NAME FUNCTION
1 IN Power Supply Input. Connect a minimum 1µF ceramic capacitor from IN to GND for bypassing high-
frequency noise on IN pin to ground.
2 GND Ground Pin. Connect to system ground.
3 EN Enable Input. Logic-high voltage on EN pin enables the device, while logic-low voltage disables the
device.
4 MODE PWM or Skip Mode Selection Input. Connect the MODE pin to GND to enable PWM mode operation.
Leave the MODE pin unconnected to enable skip mode operation.
5 PGOOD
Open-Drain Power Good Output. Connect PGOOD pin to output voltage or IN pin through an external
pullup resistor to generate a “high” level if the output voltage is above 93% of the target regulated
voltage. If not used, leave this pin unconnected. The PGOOD is driven low if the output voltage is below
90% of the target regulated voltage.
6 FB Feedback Input. Connect FB to the center of the external resistor-divider from output to GND to set the
output voltage.
7 VOUT Output Voltage Input. Connect the positive terminal of the output voltage to the VOUT pin.
8 LX Switching Node. Connect LX pin to the switching node of the inductor.
— EP Exposed Pad. Connect exposed pad to the system ground.
+
MAX17620
IN
TDFN
(2mm x2mm)
TOP VIEW
LX
87 6 5
432
1
V
OUT
FB PGOOD
GND EN MODE
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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Pin Conguration
Pin Description
HIGH-SIDE
CURRENT SENSE
LOGIC
HSCS
LOW SIDE
CURRENT SENSE
LOGIC
DRIVER
LOGIC
GND
LX
BANDGAP
HSLIM
IPFM
LSLIM
ZX
CONTROL
LOGIC
IN
EN
PGOOD
SOFT
START
CLK
FB
PWM
VREF
SLOPE
HSCS
++
MAX17620
FB
0.748V
2V
UVLO
THERMAL
SHUTDOWN
CHIPEN
OSCILLATOR
CLK
0.55 x V
IN
MODE
IN
PFM_EN
VOUT
POK
THSD
VREF
SKIP
PFM_EN
5µA
LSCS
ERROR
AMPLIFIER
SLOPE
COMPENSATION
PWMSKIP
CHIPEN
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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Block Diagram
Detailed Description
The MAX17620 is a high-frequency, high-efficiency
synchronous step-down DC-DC converter with integrated
MOSFETs that operates over a 2.7V to 5.5V input voltage
range. The device supports up to 600mA load current
and 1.5V to 100% VIN output voltage. High-frequency
operation allows the use of small, low-cost inductors and
capacitors.
The device features a MODE pin to set the device to operate in
PWM or skip mode under light-load conditions. In PWM Mode, the
device operates with its nominal switching frequency of 4MHz
over entire load current range. In skip mode, the device skips
some cycles at light loads thereby reducing the switching
frequency and achieving high efficiency. The device
features a soft-start, open-drain power-good signal
(PGOOD) and enable input (EN).
Control Architecture
The device uses an internally compensated, peak-
current-mode-control architecture. The high-side MOSFET
is turned on at each clock edge and the low-side MOSFET
is turned off. The high-side MOSFET remains on until the
sum of the high-side MOSFET current-sense voltage and
the internal slope compensating ramp voltage hits the
control voltage generated by the error amplifier. At this
moment, the high-side MOSFET is turned off and the low-
side MOSFET is turned on.
During the high-side MOSFET on-time, the inductor
current ramps up and stores energy. During the low-side
MOSFET on-time, the inductor current ramps down and
releases the stored energy to the output.
Enable Input (EN)
The device is enabled by setting the EN pin to a logic-
high. Accordingly, a logic-low disables the device. When
the device is enabled, an internal soft-start circuitry
monotonically ramps up the error amplifier’s reference
voltage from 0 to 0.8V in fixed soft-start time of 1ms. This
causes the output voltage to ramp monotonically from 0V
to set voltage. It also avoids excessive inrush current and
prevents excessive voltage drop of batteries with high
internal impedance.
Driving EN low disables the switching and output is
discharged with a typical discharge resistor of 225Ω. The
same happens when the device gets disabled by thermal
shutdown or undervoltage-lockout trigger.
Mode Selection (MODE)
The device can be set to operate in either PWM mode
or skip mode under light-load conditions by connecting
the MODE pin to ground or leaving it unconnected.
Connecting the MODE pin to ground sets the device to
PWM mode and leaving it unconnected sets the device
to skip mode.
In PWM mode, the device operates with its nominal
switching frequency of 4MHz over the entire load current
range and the inductor current is allowed to go negative.
PWM mode is useful in applications where constant
switching frequency is desired.
In skip mode, the device skips pulses at light loads for
high efficiency and the inductor current is not allowed to
go negative. In this mode, when the output voltage falls
below the target value, the internal high-side MOSFET
is turned on until the inductor current reaches to peak
current threshold in skip mode. Once the high-side FET is
turned off, the low-side FET is turned on until the inductor
current falls to zero. The device enters into PWM mode if
the output voltage is below the target voltage during the
next 3 clock cycles after the inductor current falls to zero. If
the output voltage is above the target value during the next
3 clock cycles, then both the high-side and low-side FETs
are turned off and the device enters hibernation mode until
the load discharges the output below the target value.
The peak current threshold in skip mode is a function
of the output inductor and is (375/L)mA, where L is the
output inductor value in µH. The advantage of the skip
mode is higher efficiency at light loads because of lower
quiescent current drawn from the supply. The disadvantage
is that the output-voltage ripple is higher compared
to that of the PWM mode operation and the switching
frequency is not constant at light loads. The device
always operates in skip mode during soft-start under light
loads independent of the MODE pin status. The peak
current threshold in skip mode during soft-start is reduced
to 50% of the value during steady-state operation.
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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Power-Good Indicator (PGOOD)
The device includes an open-drain power good output
that indicates the output voltage status. PGOOD goes
high impedance when the output voltage is above 93.5%
of the target value, and goes low when the output voltage
is below 90% of the target value.
Startup Into a Prebiased Output
The device is capable of soft-starting into a prebiased
output without discharging the output. The device
ramps up the output voltage monotonically from the
prebiased level to the target level during the soft-start
period if the prebiased voltage is less than the target
output voltage. If the prebiased voltage is more than the
target output voltage, no switching happens during the
soft-start period. The device operation after the completion
of the soft-start period under prebiased output condition
(where the prebiased voltage is higher than the target
output voltage) depends on the PWM/skip mode. In PWM
Mode, the device tries to regulate the output voltage to the
target level by sinking current from the prebiased source.
In skip mode, the device does not initiate switching until
the output voltage falls below the target output voltage.
100% Duty-Cycle Operation
The device can provide 100% duty-cycle operation. In
this mode, the high-side switch is constantly turned on,
while the low-side switch is turned off. This is particularly
useful in battery-powered applications to achieve longest
operation time by taking full advantage of the whole
battery-voltage range. The minimum input voltage to
maintain the output-voltage regulation can be calculated
as:
VIN_MIN = VOUT + (IOUT x RON)
where,
VIN_MIN is the minimum input voltage
VOUT is the target output voltage
IOUT is the load current
RON is the sum of the high-side FET on-resistance and
the output inductor DCR
Undervoltage Lockout
The device features an integrated input undervoltage
lockout (UVLO) feature that turns the device on/off based
on the voltage at the IN pin. The device turns on if the IN
pin voltage is higher than the UVLO threshold (VIN_UVLO)
of 2.6V (typ) (assuming EN is at logic-high) and turns off
when the IN pin voltage is 200mV (VIN_UVLO_HYS) below
the VIN_UVLO.
Overcurrent Protection
The device features a robust overcurrent-protection
scheme that protects the device and inductor under
overload and output short-circuit conditions. A cycle-by-
cycle peak current limit turns off the high-side MOSFET
and turns on the low-side MOSFET whenever the high-
side MOSFET current exceeds the internal peak current
limit of 1.45A (typ). The low-side MOSFET remains on
until the next clock cycle. The high-side MOSFET is
turned on again, if the inductor current is less than the
valley current limit at the next clock rising edge. Otherwise,
the low-side MOSFET is kept on for the next clock cycle
as well. Under severe overload conditions, the current will
not exceed 1.45A. If the overload condition is removed,
the part recovers smoothly to target output voltage with no
overshoot.
Thermal Shutdown
Thermal-shutdown protection limits the total power
dissipation in the device. When the device junction
temperature exceeds +165°C, an on-chip thermal
sensor shuts down the device, allowing it to cool. The
thermal sensor turns the device on again after the junction
temperature cools by 10°C.
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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Applications information
Inductor Selection
Three key inductor parameters must be specified to select
output inductor:
1) Inductor value
2) Inductor saturation current
3) DC resistance of the Inductor
The device’s internal slope compensation and current
limit are optimized for 1µH output inductor. Select 1µH
inductor with a saturation current rating higher than the
maximum peak current limit of 1.9A. Inductor with low
DC resistance improves the efficiency of the system.
Selecting ferrite-cored inductors reduces the core losses
and improves efficiency. Table 1 lists recommended
inductors for use in designs.
Output Capacitor Selection
X7R ceramic capacitors are preferred as output capaci-
tors due to their stability over temperature in industrial
applications. The device’s internal loop-compensation
parameters are optimized for 10µF output capacitors. The
device requires a minimum of 10µF (typ) capacitance for
stability. Table 2 lists the recommended output capacitors.
Capacitors rated less than 4V can be selected for output
voltages less than 3V.
Table 1. List of Recommended Inductors
Table 2. List of Recommended Output Capacitors
INDUCTANCE
(µH)
CURRENT
RATING
(A)
DC RESISTANCE
(TYP)
(mΩ)
DIMENSIONS
L x W x H
(mm3)
PART NUMBER MANUFACTURER
1 2.6 37 2.5 x 2 x 1.2 IFSC1008ABER1R0M01 Vishay Dale
1 3.2 50 2.5 x 2 x 1 252010CDMCDS-1R0MC Sumida
1 2.3 48 2.5 x 2 x 0.9 CIG22E1R0MNE
Samsung
Electro-Mechanics
America
1 2.3 48 2.5 x 2 x 1.2 MLP2520K1R0MT0S1 TDK Corporation
1 2.7 60 2 x 1.6 x 1 MAKK2016H1ROM Taiyo Yuden
CAPACITANCE
(µF)
DIELECTRIC
TYPE
VOLTAGE RATING
(V) PACKAGE PART
NUMBER MANUFACTURER
10 X7R 6.3 0805 C2012X7R0J106K125AB TDK Corporation
10 X7R 6.3 0805 GRM21BR70J106KE76K Murata Americas
10 X7R 6.3 0805 JMK212B7106KG-T Taiyo Yuden
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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Input Capacitor Selection
The input filter capacitor reduces peak current drawn from
the power source and reduces noise and voltage ripple
on the input caused by the circuit’s switching. The input
capacitor RMS current (IRMS) is defined by the following
equation:
OUT IN OUT
RMS_CIN OUT(MAX) IN
x( )
xV VV
II V
−
=
where:
IOUT(MAX) is the maximum load current
VIN is the input voltage
VOUT is the output voltage
Use low-ESR ceramic capacitors as the input capaci-
tor. X7R temperature coefficient capacitors are recom-
mended in industrial applications for their stability over
temperature. Calculate the input capacitor value using the
following equation:
OUT(MAX) OUT IN OUT
IN
SW IN I 2
N
x x( )I V VV
C
f VVxx xη
−
=∆
where:
fSW is the switching frequency (= 4MHz)
η is the efficiency
In applications where the input source is located distant
from the device input, an electrolytic capacitor should
be added in parallel to the ceramic capacitor to provide
necessary damping for potential oscillations caused by
the inductance of the longer input cable and the ceramic
capacitor.
Adjusting the Output voltage
The MAX17620 supports output voltages from 1.5V to
100% VIN. Set the output voltage with a resistor-divider
connected from the positive terminal of the output voltage
to the ground (see Figure 1). Choose R2 in the range of
10kΩ to 100kΩ and calculate the R1 using the following
equation:
OUT
R1 x 1R2 .8

= −


Power Dissipation
Ensure that the junction temperature of the device does
not exceed +125°C under the operating conditions. At a
particular operating condition, the power losses that lead
to the temperature rise of the device are estimated as
follows:
()
LOSS OUT OUT DCR
2
1
P P IRx1 x


= −−


η


where,
POUT is the output power given by the following equation:
POUT = VOUT x IOUT
See the Typical Operating Characteristics for the power-
conversion efficiency or measure the efficiency to deter-
mine the total power losses.
The junction temperature (TJ) of the device can be
estimated at any ambient temperature (TA) from the
following equation:
TJ = TA + (θJA x PLOSS)
where θJA is the junction-to-ambient thermal resistance
of the package (102°C/W for a four-layer board measured
using JEDEC specification JESD51-7).
If the application has a thermal-management system that
ensures the exposed pad of the device is maintained at a
given temperature (TEP), the junction temperature can be
estimated using the following formula:
TJ = TEP + (θJC x PLOSS)
where θJC is the junction-to-case thermal resistance of
the device (8°C/W)
Figure 1. Adjusting the Output Voltage
R1
R2
MAX17620
FB
V
OUT
GND
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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PCB Layout Guidelines
Careful PCB layout is critical to achieve clean and stable
operation. In particular, the traces that carry pulsating current
should be short and wide so that the parasitic inductance
formed by these traces can be minimized. Follow the
following guidelines for good PCB layout.
●Place the input capacitor as close as possible to the
IN and GND pins. Use a wide trace to connect the
input capacitor to the IN and GND pins to reduce the
trace inductance.
●Minimize the area formed by the LX pin and the inductor
connection to reduce the radiated EMI.
●Ensure that all the feedback connections are short.
●Route the LX node away from the FB, VOUT and
MODE pins.
For a sample PCB layout that ensures first-pass success,
refer to the MAX17620 evaluation kit layout available at
http://www.maximintegrated.com
Typical Application Circuit
Figure 2. 1.8V, 600mA Step-Down Regulator
LX
VOUT
FB
GND
MODE
IN
PGOOD
EN
2.7V TO 5.5V
R1
24kΩ
V
OUT
1.8V/600mA
C
IN
2.2µF
L
1µH
MAX17620
C
IN
: 2.2µF/10V/0603/X7R,GRM188R71A225KE15D, MUR
ATA
L1: 1μH, 60mΩ, MAKK2016H1ROM, TAIYO-YUDEN
C
OUT
:10μF/6.3V/0805/X7R, GRM21BR70J106KE76K, MURATA
C
OUT
10µF
R2
19.1kΩ
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
PART TEMP RANGE PIN-PACKAGE
MAX17620ATA+T -40°C to +125°C 8 TDFN
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 TDFN T822+3C 21-0168 90-0065
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
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Ordering Information
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: CMOS
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 3/15 Initial release —
1 6/15 Updated MODE pin description, updated global specications for the Typical
Operating Characteristics section, and updated table 1 and table 2 4–6, 7, 9, 11
2 10/15 Updated Typical Applications Circuit, replaced/added plots in Typical Operating
Characteristics section, and updated Block Diagram 1-6, 8, 10–11, 13
3 7/16 Fixed minor text errors 9, 11
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.
MAX17620 4MHz, Miniature 600mA, Synchronous Step-Down
DC-DC Converter with Integrated MOSFETs
© 2016 Maxim Integrated Products, Inc.
│
15
Revision History
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