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MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
General Description
Benefits and Features
The MAX20029/MAX20029B/MAX20029C/MAX20029D
power-management ICs (PMICs) integrate four low-voltage, high-efficiency, step-down DC-DC converters. Each
of the four outputs is factory or resistor programmable
between 1V to 4.0V (MAX20029/MAX20029B) or 0.7V
to 3.8V (MAX20029C/MAX20029D). The MAX20029/
MAX20029C has two 0.5A/1A/1.5A channels and two
0.5A/1.5A channels, while the MAX20029B/MAX20029D
has two 0.5A/1.5A channels and by combining channels
1 and 2, a single 2A/3A channel. The PMICs operate from
3.0V to 5.5V, making them ideal for automotive point-ofload and post-regulation applications.
The PMICs feature fixed-frequency PWM-mode operation
with a switching frequency of 2.2MHz. High-frequency
operation allows for an all-ceramic capacitor design
and small-size external components. The low-resistance
on-chip switches ensure high efficiency at heavy loads
while minimizing critical inductances, making the layout
a much simpler task with respect to discrete solutions.
Internal current sensing and loop compensation reduce
board space and system cost.
The PMICs offer a spread-spectrum option to reduce
radiated emissions. Two of the four buck converters
operate 180º out-of-phase with the internal clock. This
feature reduces the necessary input capacitance and
improves EMI as well. All four buck converters operate in
constant PWM mode outside the AM band. The PMICs
offer a SYNC input to synchronize to an external clock.
The PMICs provide individual enable inputs and power-good/
reset outputs, as well as factory-programmable PG times.
The PMICs offer several important protection
features including: input overvoltage protection, input
undervoltage lockout, cycle-by-cycle current limiting, and
overtemperature shutdown.
The MAX20029/MAX20029B/MAX20029C/MAX20029D
PMICs are available in a 28-pin TQFN package with an
exposed pad and are specified for operation over the
-40ºC to +125ºC automotive temperature range.
Applications
● Automotive
● Industrial
19-100083; Rev 11; 2/20
● Quad Step-Down DC-DC Converters with Integrated
FETs
● Operate from 3.0V to 5.5V Supply Voltage
● 0.7V to 4.0V Fixed or Adjustable Output Voltage
● 2.2MHz Switching Frequency
● MAX20029/MAX20029C: Up to Four 1.5A Channels
● MAX20029B/MAX20029D: Up to One 3A + Two 1.5A
Channels
● Designed to Improve Automotive EMI Performance
• Forced-PWM Operation
• Two Channels 180º Out-of-Phase
• SYNC Input
• Spread-Spectrum Option
● Soft-Start and Supply Sequencing Reduces Inrush
Current
● Individual Enable Inputs and Power-Good Outputs to
Simplify Sequencing
● OV Input-Voltage Monitoring
● Overtemperature and Short-Circuit Protection
● 28-Pin (5mm x 5mm x 0.8mm) TQFN-EP Package
● -40ºC to +125ºC Operating Temperature Range
Ordering Information appears at end of data sheet.
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Simplified Block Diagram
VOUT1
MAX20029
10kΩ
PG_
EN_
CONTROL
5V
VA
1µF
SS OSC
SYNC
GND
4 CHANNELS
5V
PV_
2.2µF
STEP-DOWN
PWM OUT_
1.0V TO 4.0V
UP TO 1.5A
LX_
1.5µH
VOUT_
22µF
PGND_
OUTS_
EN
EP
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Maxim Integrated │ 2
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Absolute Maximum Ratings
PV_ to PGND_......................................................-0.3V to +6.0V
VA to GND.............................................................-0.3V to +6.0V
OUTS_, EN_, PG_, SYNC to GND................-0.3V to VA + 0.3V
PV_ to PV_............................................................-0.3V to +0.3V
PGND_ to GND.....................................................-0.3V to +0.3V
LX_ to PGND...............................................-1.0V to PV_ + 0.3V
LX_ Continuous RMS Current...............................................2.0A
Output Short-Circuit Duration.....................................Continuous
Continuous Power Dissipation (TA = +70ºC)
28-pin TQFN (derate 28.6mW/ºC above +70ºC)........2285mW
Operating Temperature Range...........................-40ºC to +125ºC
Junction Temperature....................................................... +150ºC
Storage Temperature Range..............................-65ºC to +150ºC
Lead Temperature (soldering, 10s).................................. +300ºC
Soldering Temperature (reflow)........................................ +260ºC
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 (Note 1)
28 TQFN
Junction-to-Ambient Thermal Resistance (θJA)...........35°C/W
Junction-to-Case Thermal Resistance (θJC)......................3°C/W
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.
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.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
28 TQFN-EP
T2855+5
21-0140
90-0025
Electrical Characteristics
(VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C under
normal conditions, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNIT
5.5
V
3.8
5
mA
TA = +25°C
0.1
2
TA = +125°C
2
GENERAL
Supply Voltage Range
VPV_
Fully operational
3.0
Supply Current
IPV0
No load, no switching,
VEN1 = VEN2 = VEN3 = VEN4 = VPV_
2.5
Shut-Off Current
IVPSD
VEN1 = VEN2 =
VEN3 = VEN4 =
VGND
Rising
Overvoltage Threshold
5.6
Hysteresis
UVLO Threshold
5.8
0.1
VPV_ falling
2.68
VPV_ falling (MAX20029D)
2.6
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fSW
V
V
VPV_ rising
PWM Switching Frequency
6
µA
3.0
2.0
2.2
2.4
MHz
Maxim Integrated │ 3
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Electrical Characteristics (continued)
(VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C under
normal conditions, unless otherwise noted.) (Note 2)
PARAMETER
Spread Spectrum
SYNC Input Frequency Range
SYMBOL
Df/f
CONDITIONS
MIN
Spread-spectrum option = enabled
(see the Selector Guide)
fSYNC
TYP
MAX
+3
1.7
UNIT
%
2.5
MHz
SYNCHRONOUS STEP-DOWN DC-DC CONVERTERS (OUT1–OUT4) MAX20029D
+1.5
ILOAD = 0mA
Fixed DC Output Accuracy
FB DC Set-Point Accuracy
Load Regulation
VSFB_
ILOAD = 0mA to IMAX
-3
+3
ILOAD = 0mA to 1.0A (MAX20029C/
MAX20029D)
-3
+3
ILOAD = 0mA to 1.0A at 125°C
(MAX20029C/MAX20029D)
-3
+3.2
ILOAD = 0mA to 1.5A (MAX20029C/
MAX20029D)
-3.75
+3
ILOAD = 0mA to 1.5A at 125°C
(MAX20029C)
-3.75
+3.2
ILOAD = 0mA (MAX20029/
MAX20029B)
ILOAD = 0mA to IMAX (MAX20029/
MAX20029B)
MAX20029
MAX20029B/
MAX20029D
(OUT3, OUT4)
MAX20029C
Per 1A of load
MAX20029B/
MAX20029D
(OUT1)
Per 2A of load
%
1015
mV
970
1030
-1.5
%
-1.5
Line Regulation
ILOAD = IMAX/2, VPV_ = 4.5V to 5.5V
+0.3
pMOS On-Resistance
VPV_ = 5.0V, ILX_ = 0.2A
125
250
mΩ
nMOS On-Resistance
VPV_ = 5.0V, ILX_ = 0.2A
100
200
mΩ
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%
Maxim Integrated │ 4
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Electrical Characteristics (continued)
(VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C under
normal conditions, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MAX20029
MAX20029C
MAX20029B/
MAX20029D
(OUT1, 2A
channel, per
LX_ pin)
pMOS Current-Limit Threshold
MAX20029B/
MAX20029D
(OUT1, 3A
channel, per
LX_) pin
OUT3/OUT4
(0.5A channel)
OUT3/OUT4
(1.5A channel)
MIN
TYP
MAX
OUT1/OUT2, Opt 1
(0.5A channel)
0.8
1.1
1.5
OUT1/OUT2, Opt 2
(1A channel)
1.4
1.65
2
OUT1/OUT2, Opt 3
(1.5A channel)
1.85
2.2
2.75
1.4
1.65
2
A
(see Selector Guide)
1.85
2.2
2.75
0.8
1.1
1.5
1.85
2.2
2.75
(see Selector Guide)
Soft-Start Ramp Time
OUTS Leakage Current
LX Leakage Current
IB_OUTS_
UNIT
3272
Cycles
Externally adjustable output
20
nA
VPV_ = 5.0V, LX_ = VPGND_ or VPV_
0.1
µA
Minimum On-Time
45
LX Rise/Fall Time
4
Duty-Cycle Range
66
ns
100
OUTS_ Discharge Resistance
VEN_ = VGND
OUT1, OUT2 Phasing
OUT3, OUT4 Phasing
ns
%
35
Ω
(Note 3)
0
Degrees
(Note 3)
180
Degrees
Thermal-Shutdown Temperature
TJ rising (Note 4)
+185
ºC
Hysteresis
(Note 4)
15
ºC
THERMAL OVERLOAD
OUTPUT POWER-GOOD INDICATORS (PG1–PG4)
Output Overvoltage Threshold
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VOUT rising (percentage of nominal
output)
106
110
114
%
Maxim Integrated │ 5
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Electrical Characteristics (continued)
(VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C under
normal conditions, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
Output Undervoltage Threshold
CONDITIONS
MIN
TYP
MAX
VOUT falling (percentage of nominal
output)
92.5
94
96
VOUT rising (percentage of nominal
output)
93.5
95
97
VOUT falling (percentage of nominal
output), MAX20029C/MAX20029D
90
94
96
VOUT rising (percentage of nominal
output), MAX20029C/MAX20029D
90.5
95
96.5
UNIT
%
UV/OV Propagation Delay
15
µs
PG_ Output High Leakage
Current
0.1
µA
PG_ Output Low Level
VPV_= 3.0V, sinking 3mA
Active Timeout Period
0.22
V
Option 1
256
Cycles
Option 2
20480
Cycles
ENABLE INPUTS (EN1–EN4)
Input High Level
VPV_ = 5.0V, VEN_ rising
Hysteresis
VPV_ = 5.0V, VEN_ falling
0.7
Pulldown Resistance
1.0
1.3
V
50
mV
100
kΩ
DIGITAL INTERFACE (SYNC)
Input Voltage High
VINH
Input Voltage Low
VINL
1.5
V
0.5
V
Input Voltage Hysteresis
70
mV
Pulldown Resistance
100
kΩ
Note 2: All units are 100% production tested at +25ºC. All temperature limits are guaranteed by design.
Note 3: Phase measurement is in relation to the rising edge of VLX_.
Note 4: Guaranteed by design. Not production tested.
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Maxim Integrated │ 6
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Typical Operating Characteristics
(VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
EFFICIENCY CURVE
toc01
100
VOUT = 3.3V
90
SUPPLY CURRENT (mA)
EFFICIENCY (%)
VOUT = 1.2V
70
VPV_ = VA = VEN_
30
VOUT = 1.8V
80
toc02
35
60
50
40
30
20
NO LOAD
25
20
15
10
5
10
0
0.001
0.01
0.1
0
1
2.7
3.2
LOAD REGULATION
VOUT1 (% NOMINAL)
toc04
3.24
3.22
100.4
100.2
100.0
99.8
3.20
0
0.2
0.4
0.6
0.8
1
1.2
99.6
1.4
2.7
3.2
3.7
4.2
4.7
5.2
5.7
LOAD CURRENT (A)
SUPPLY VOLTAGE (V)
SWITCHING FREQUENCY
vs. TEMPERATURE
P-CHANNEL SWITCH RESISTANCE
vs. SUPPLY VOLTAGE
0.35
P-CHANNEL SWITCH RESISTANCE (Ω)
toc05
103
102
101
100
99
98
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
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toc06
VOUT3 (V)
3.28
3.26
fSW (% NOMINAL)
5.7
100.6
3.30
97
5.2
VOUT1 = 1.8V
3.32
3.18
4.7
100.8
VOUT = 3.3V
3.34
4.2
LINE REGULATION
toc03
3.36
3.7
SUPPLY VOLTAGE (V)
LOAD CURRENT (A)
TA = +125ºC
0.30
TA = +25ºC
0.25
0.20
0.15
TA = -40ºC
0.10
0.05
0
2.7
3.2
3.7
4.2
4.7
5.2
5.7
VPV_ (V)
Maxim Integrated │ 7
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
PV4
LX4
PGND4
PGND3
LX3
PV3
TOP VIEW
EN4
Pin Configuration
21
20
19
18
17
16
15
OUTS4 22
14
OUTS3
PG4 23
13
EN3
12
PG3
11
GND
10
PG2
9
EN2
8
OUTS2
GND 24
MAX20029
MAX20029B
SYNC 25
VA 26
EP = GND
PV1
4
5
6
LX2
EN1
3
PGND2
2
LX1
1
PGND1
+
7
PV2
PG1 27
OUTS1 28
TQFN
5mm x 5mm
Pin Description
PIN
NAME
1
EN1
Active-High Digital Enable Input for Buck 1. Driving EN1 high enables Buck 1.
2
PV1
Buck 1 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV1 to PGND1 as close
as possible to the device.
3
LX1
Buck 1 Switching Node. LX1 is high impedance when the device is off.
4
PGND1
Power Ground for Buck 1
5
PGND2
Power Ground for Buck 2
6
LX2
Buck 2 Switching Node. LX2 is high impedance when the device is off. Connect to LX1 for the
MAX20029B/MAX20029D.
7
PV2
Buck 2 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV2 to PGND2 as close
as possible to the device.
8
OUTS2
9
EN2
Active-High Digital Enable Input for Buck 2. Driving EN2 high enables Buck 2. Connect to ground
for the MAX20029B/MAX20029D.
10
PG2
Open-Drain, Active-High, Power-Good Output for Buck 2. To obtain a logic signal, pull up PG2
with an external resistor connected to a positive voltage equal to or lower than VA. Connect to
ground for the MAX20029B/MAX20029D.
11
GND
Ground
12
PG3
Open-Drain, Active-High, Power-Good Output for Buck 3. To obtain a logic signal, pull up PG3
with an external resistor connected to a positive voltage equal to or lower than VA.
13
EN3
Active-High Digital Enable Input for Buck 3. Driving EN3 high enables Buck 3.
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FUNCTION
Buck 2 Voltage-Sense Input. Connect to output capacitor. Connect to ground for the
MAX20029B/MAX20029D.
Maxim Integrated │ 8
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Pin Description (continued)
PIN
NAME
14
OUTS3
15
PV3
Buck 3 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV3 to PGND3 as close
as possible to the device.
16
LX3
Buck 3 Switching Node. LX3 is high impedance when the device is off.
17
PGND3
Power Ground for Buck 3
18
PGND4
Power Ground for Buck 4
19
LX4
Buck 4 Switching Node. LX4 is high impedance when the device is off.
20
PV4
Buck 4 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV4 to PGND4 as close
as possible to the device.
21
EN4
Active-High Digital Enable Input for Buck 4. Driving EN4 high enables Buck 4.
22
OUTS4
23
PG4
Open-Drain, Active-High, Power-Good Output for Buck 4. To obtain a logic signal, pull up PG4
with an external resistor connected to a positive voltage equal to or lower than VA.
24
GND
Analog Ground
25
SYNC
SYNC Input. Supply an external clock to control the switching frequency. Connect SYNC to
PGND_ to use the default switching frequency.
26
VA
Analog Voltage Supply. Connect a 1µF or larger ceramic capacitor from VA to GND as close as
possible to the device. Connect to the same supply as PV_ inputs.
27
PG1
Open-Drain, Active-High, Power-Good Output for Buck 1. To obtain a logic signal, pull up PG1
with an external resistor connected to a positive voltage equal to or lower than VA.
28
OUTS1
—
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EP
FUNCTION
Buck 3 Voltage Sense Input
Buck 4 Voltage Sense Input
Buck 1 Voltage Sense Input
Exposed Pad. Connect the exposed pad to ground. Connecting the exposed pad to ground does
not remove the requirement for proper ground connections to PGND1–PGND4 and GND. The
exposed pad is attached with epoxy to the substrate of the die, making it an excellent path to
remove heat from the IC.
Maxim Integrated │ 9
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
CURRENT-SENSE
AMP
PV1—PV4
VREF
PEAK
CURRENT
COMP
RAMP
GENERATOR
PV1
∑
PWM
COMP
PGND1
CONTROL
LOGIC
VREF
PGND1
SOFT-START
GENERATOR
OUTS1—
OUTS4
LX1—LX4
PV1
CLK180 CLK
PGND1
—PGND4
VALLEY
CURRENT
LIM COMP
P1-OK
FEEDBACK
SELECT
SEL
VREF
SYNC
OSC
P-OK[1:4]
OTP
CLK
VOLTAGE
REFERENCE
MAX20029
MAX20029B
MAX20029C
EN1
TRIMBITS
CLK180
VREF
UVLO
VA
VA
PG1
PG2
EN2
EN3
EN4
MAIN
CONTROL
LOGIC
PG3
PG4
GND
Figure 1. Internal Block Diagram
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Maxim Integrated │ 10
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Detailed Description
The MAX20029/MAX20029B/MAX20029C/MAX20029D
PMICs offer four high-efficiency, synchronous step-down
converters that operate with a 3.0V to 5.5V input voltage
range and provide a 0.7V to 4.0V output voltage range.
The PMICs deliver up to 1.5A of load current per output,
and achieve ±3% output error over load, line, and temperature ranges.
The PMICs feature fixed-frequency PWM-mode operation
with a 2.2MHz switching frequency. An optional spreadspectrum frequency modulation minimizes radiated
electromagnetic emissions due to the switching frequency,
while a factory-programmable synchronization input (SYNC)
allows the device to synchronize to an external clock.
Integrated low RDS(ON) switches help minimize efficiency
losses at heavy loads and reduce critical/parasitic
inductance, making the layout a much simpler task with
respect to discrete solutions.
The PMICs are offered in factory-preset output voltages to
allow customers to achieve ±3% output-voltage accuracy,
without using expensive 0.1% resistors. In addition,
adjustable output-voltage versions can be set to any
desired values between 1.0V and 4.0V using an external
resistive divider. See the Selector Guide for available
options.
Additionally, each converter features soft-start, PG_
output, overcurrent, and overtemperature protections
(see Figure 1).
Control Scheme
The PMICs use peak current-mode control, and feature
internal slope compensation and loop compensation, both
of which reduce board space and allow a very compact
solution.
Hybrid Load-Line Architecture
The PMICs feature hybrid load-line architecture to reduce
the output capacitance needed, potentially saving system
cost and size. This results in a measurable load-transient
response.
Input Overvoltage Monitoring (OV)
The PMICs feature an input overvoltage-monitoring circuit
on the input supply. When the input exceeds 5.8V (typ)
all power-good indicators (PG_) go low. When the input
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Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
supply returns to within the operating range of 5.7V
(typ) or less during the timeout period, the power-good
indicators go high.
Input Undervoltage Lockout (UVLO)
The PMICs feature an undervoltage lockout on the PV_
inputs set at 2.77V (typ) falling. This prevents loss of
control of the device by shutting down all outputs. This
circuit is only active when at least one buck converter is
enabled.
Power-Good Outputs (PG_)
The PMICs feature an open-drain power-good output for
each of the four buck regulators. PG_ asserts low when
the output voltage drops 6% below the regulated voltage
or 10% above the regulated voltage for approximately
15µs. PG_ remains asserted for a fixed number of
switching cycles after the output returns to its regulated
voltage. See the Selector Guide for available options.
PG_ asserts low during soft-start and in shutdown. PG_
becomes high impedance when Buck_ is in regulation.
Connect PG_ to a logic supply with a 10kΩ resistor.
Soft-Start
The soft-start time limits startup inrush current by forcing the output voltage to ramp up towards its regulation
point. During soft-start, the converters operate in skip
mode to prevent the outputs from discharging. Expected
soft-start time for MAX20029 and MAX20029B is approximately 1.5ms, and approximately 1ms for MAX20029C/
MAX20029D (scaling factor is applied due to internal voltage reference difference).
+5.0%
+1.5%
0%
-1.0%
-3.5%
4µs
4µs
1.0A
0A
1µs
1µs
Figure 2. Load-Transient Response
Maxim Integrated │ 11
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Spread-Spectrum Option
The PMICs feature a linear spread-spectrum (SS)
operation, which varies the internal operating frequency
between fSW and (fSW + 3%). The internal oscillator is
frequency modulated at a rate of 1.5kHz with a frequency
deviation of 3% (see Figure 3). This function does
not apply to an oscillation frequency applied externally
through the SYNC pin. Spread spectrum is a factoryselectable option. See the Selector Guide for available
options.
Synchronization (SYNC)
The PMICs feature a SYNC input to allow the internal
oscillator to synchronize with an external clock. SYNC
accepts signal frequencies in the range of 1.7MHz <
fSYNC < 2.5MHz. Connect to PGND_ if the SYNC feature
is not used.
Current-Limit /Short-Circuit Protection
The PMICs offer a current-limit feature that protects the
devices against short-circuit and overload conditions on
each output. In the event of a short-circuit or overload
condition at an output, the high-side MOSFET remains on
until the inductor current reaches the high-side MOSFET’s
current-limit threshold. The converter then turns on the
low-side MOSFET and the inductor current ramps down.
The converter allows the high-side MOSFET to turn on
only when the inductor current ramps down to the lowside MOSFET’s current threshold. This cycle repeats until
the short or overload condition is removed.
Overtemperature Protection
cools by 15°C. The IC goes through a standard power-up
sequence as defined in the Soft-Start section.
Applications Information
Adjustable Output-Voltage Option
The MAX20029/MAX20029B PMICs feature adjustable
output voltages (see the Selector Guide for more details),
which allows the customer to set the outputs to any voltage between 1.0V and VPV_ - 0.5V (up to 4.0V). Connect
a resistive divider from output (VOUT_) to OUTS_ to GND
to set the output voltage (see Figure 4). Select R2 (OUTS_
to the GND resistor) ≤ 100kΩ. Calculate R1 (VOUT_ to the
OUTS_ resistor) with the following equation:
VOUT_
− 1
=
R1 R2
VOUTS_
where VOUTS_ = 1.0V (see the Electrical Characteristics
table). The output voltage is nominal at 50% load current.
The external feedback resistive divider must be frequency
compensated for proper operation. Place a capacitor
across R1 in the resistive divider network. Use the
following equation to determine the value of the capacitor:
R2
R2
> 1, C1 =
C
R1
R1
else C1 C,
where C 15pF
=
=
If
Thermal-overload protection limits the total power dissipation in the PMICs. When the junction temperature exceeds
185°C (typ), an internal thermal sensor shuts down the
step-down converters, allowing the IC to cool. The thermal
sensor turns on the IC again after the junction temperature
VOUT_
R1
MAX20029
MAX20029B
fSW + 3%
C1
OUTS_
R2
INTERNAL
OSCILLATOR
FREQUENCY
fSW
t
t + 667µs
t + 1.334ms
TIME
Figure 4. Adjustable Output-Voltage Configuration
Connect OUTS_ to VOUT_ for a fixed 1.0V output voltage.
Figure 3. Effect of Spread Spectrum on Internal Oscillator
www.maximintegrated.com
Maxim Integrated │ 12
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Inductor Selection
The PMICs are optimized for use with a 1.5µH inductor
on outputs configured for 0.5A, 1A, or 1.5A, and a 1.0µH
inductor for an output configured for 2A or 3A. For output
voltages less than 0.9V, 0.47μH is recommended.
Input Capacitor
The PMICs are designed to operate with a single 2.2µF
ceramic bypass capacitor on each PV_ input. Phase
interleaving of the four buck converters contributes to
a lower required input capacitance by canceling input
ripple currents. Place the bypass capacitors as close as
possible to their corresponding PV_ input to ensure the
best EMI and jitter performance.
Output Capacitor
All outputs of the PMICs are optimized for use with ceramic
capacitors.
For VOUT/VIN > 0.2:
C OUT_MIN =
20
µF
VOUT
C OUT_NOM =
33
µF
VOUT
For VOUT/VIN ≤ 0.2:
C OUT_MIN =
40
µF
VOUT
C OUT_NOM =
60
VOUT
µF
Additional output capacitance can be used if better voltage ripple or load-transient response is required (see
Figure 2). To guarantee stability, it is recommended that
the phase margin be measured under the worst-case
deration of the output capacitor(s). Due to the soft-start
sequence, the PMICs are unable to drive arbitrarily large
output capacitors.
Thermal Considerations
How much power the package can dissipate strongly
depends on the mounting method of the IC to the PCB
and the copper area for cooling. Using the JEDEC test
standard, the maximum power dissipation allowed is
2285mW in the TQFN package. More power dissipation
can be handled by the package if great attention is given
during PCB layout. For example, using the top and bottom
copper as a heatsink and connecting the thermal vias to
one of the middle layers (GND) transfers the heat from the
package into the board more efficiently, resulting in lower
www.maximintegrated.com
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
junction temperature at high power dissipation in some
PMIC applications. Furthermore, the solder mask around
the IC area on both top and bottom layers can be removed
to radiate the heat directly into the air. The maximum
allowable power dissipation in the IC is as follows:
PMAX =
(TJ(MAX) − TA )
θ JC + θ CA
where TJ(MAX) is the maximum junction temperature
(+150°C), TA is the ambient air temperature, θJC (3°C/W
for the 28-pin TQFN) is the thermal resistance from the
junction to the case, and θCA is the thermal resistance from
the case to the surrounding air through the PCB, copper
traces, and the package materials. θCA is directly related
to system-level variables and can be modified to increase
the maximum power dissipation.
The TQFN package has an exposed thermal pad on its
underside. This pad provides a low thermal-resistance path
for heat transfer into the PCB. This low thermally resistive
path carries a majority of the heat away from the IC. The
PCB is effectively a heatsink for the IC. The exposed pad
should be connected to a large ground plane for proper
thermal and electrical performance. The minimum size
of the ground plane is dependent upon many system
variables. To create an efficient path, the exposed pad
should be soldered to a thermal landing, which is connected
to the ground plane by thermal vias. The thermal landing
should be at least as large as the exposed pad and can be
made larger depending on the amount of free space from
the exposed pad to the other pin landings. A sample layout
is available on the evaluation kit to speed designs.
PCB Layout Guidelines
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. Use a multilayer board
whenever possible for better noise immunity and power
dissipation. Follow these guidelines for good PCB layout:
1) Use a large contiguous copper plane under the PMIC
packages. Ensure that all heat-dissipating components
have adequate cooling.
2) Keep the high-current paths short, especially at the
ground terminals. This practice is essential for stable,
jitter-free operation. The high current path comprising
of input capacitor, inductor, and the output capacitor
should be as short as possible.
3) Keep the power traces and load connections short. This
practice is essential for high efficiency. Use thick copper
PCBs (2oz vs. 1oz) to enhance full-load efficiency.
4) Use a single ground plane to reduce the chance of
ground potential differences. With a single ground
plane, enough isolation between analog return signals
and high-power signals must be maintained.
Maxim Integrated │ 13
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Typical Operating Circuits
VIN
/4
4x2.2 µF
VIN
/4
PV1–PV4
OUTS1
MAX20029/
MAX20029C
EN1–EN4
LX1
OUTS2
PG1–PG4
1.5 µH
LX2
VA
VOUT2
22 µF
PGND2
GND
OUTS4
OUTS3
1.5 µH
VOUT4
22 µF
VOUT1
22 µF
PGND1
20 kΩ
VIN
1.5 µH
1.5 µH
LX4
LX3
PGND4
PGND3
VOUT3
22 µF
EP
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Maxim Integrated │ 14
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Typical Operating Circuits (continued)
VIN
4x2.2 µF
VIN
/4
PV1–PV4
OUTS1
MAX20029B
MAX20029D
/3
EN1, 3, 4
VIN
LX1
LX2
VOUT1
47µF
PGND1
PGND2
20kΩ
/3
1µH
PG1, 3, 4
PG2
EN2
OUTS2
VA
GND
OUTS4
OUTS3
1.5µH
VOUT4
22µF
1.5µH
LX4
LX3
PGND4
PGND3
VOUT3
22µF
EP
www.maximintegrated.com
Maxim Integrated │ 15
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Selector Guide
IOUT
(A)
PART
VOUT
(V)
CH1
CH2
CH3
CH4
CH1
CH2
MAX20029ATIA/V+
1.5
1.5
1.5
1.5
ADJ
MAX20029ATIB/V+
1.0
1.0
1.5
1.5
1.5
MAX20029ATIC/V+
1.0
1.0
1.5
1.5
MAX20029ATID/V+
1.0
1.0
1.5
MAX20029ATIF/V+
1.5
1.5
1.5
MAX20029BATIA/V+
3.0
―
MAX20029BATIB/V+
3.0
MAX20029BATIC/V+
3.0
MAX20029BATID/V+
MAX20029BATIE/V+**
SPREAD
SPECTRUM
PG_ TIMEOUT
(CYCLES)
CH3
CH4
ADJ
ADJ
ADJ
Off
256
1.8
1.15
1.4
+3%
256
1.8
1.35
3.3
1.2
+3%
256
0.5
1.0
1.8
ADJ
3.3
+3%
1.5
1.0
1.8
ADJ
3.3
+3%
256
1.5
1.5
ADJ
―
ADJ
ADJ
Off
20,480
―
1.5
1.5
1
―
1.8
1.5
+3%
20,480
―
1.5
1.5
1.1
―
1.8
1.0
Off
256
3.0
―
1.5
0.5
1.0
―
1.8
1.2
+3%
256
3.0
—
1.5
1.5
1.5
—
1.8
3.3
+3%
256
MAX20029CATIA/V+
1.5
1.5
1.5
1.5
3.3
1.8
1.0
0.7
Off
256
MAX20029CATIB/V+
1.0
1.0
0.5
1.5
1.5
0.9
1.1
0.7
+3%
256
MAX20029CATIC/V+**
1.5
1.5
1.5
1.5
1.8
3.3
0.85
1.8
+3%
256
3.0
—
1.5
1.5
1.1
—
0.7
1.8
Off
20,480
MAX20029
MAX20029B
256
MAX20029C
MAX20029D
MAX20029DATIA/V+
Note: Contact factory for custom configuration. Factory-selectable features include:
CH1/CH2 Current Configuration: 0.5A, 1.0A, or 1.5A (both channels have the same current level)
CH3, CH4 Current Configuration: 0.5A or 1.5A
DC-DC Voltages:
• (MAX20029/MAX20029B) Adjustable, or a fixed voltage between 1.0V and 4.0V in 50mV steps
• (MAX20029C) Fixed voltages between 0.7V and 3.8V in 50mV steps
Spread Spectrum: Off, +3%, or +6%
PG_ Active Timeout Period: 256 or 20,480 clock cycles
CH1 Current Configuration: 2.0A or 3.0A
**Future product—contact factory for availability
See the Ordering Information table for other options.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX20029ATI_/V+
-40°C to +125°C
28 TQFN-EP*
MAX20029BATI_/V+
-40°C to +125°C
28 TQFN-EP*
MAX20029CATI_/V+
-40°C to +125°C
28 TQFN-EP*
MAX20029DATI_/V+
-40°C to +125°C
28 TQFN-EP*
Note: Insert the desired suffix letter (from the Selector Guide)
into the blank area "_" to indicate factory-selectable features.
/V denotes an automotive qualified part that conforms to
AEC-Q100.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
**Future part—contact factory for availability.
www.maximintegrated.com
Maxim Integrated │ 16
MAX20029/MAX20029B/
MAX20029C/MAX20029D
Automotive Quad/Triple Low-Voltage
Step-Down DC-DC Converters
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
6/17
Initial release
1
9/17
Replaced TOCs 1, 2, 3, 4 deleted TOCs 6–9, and renumbered TOC10 to TOC05 and
TOC12 to TOC06; added MAX20029ATIC/V+ (as a future product) and
MAX20029BATIB/V+ to the Selector Guide
2
10/17
Removed future product status from MAX20029ATIC/V+ and added future product
status on MAX20029BATIB/V+ in the Selector Guide
3
7/18
Updated title, General Description, Benefits and Features, and Detailed Description;
updated Electrical Characteristic table, Figure 1, Typical Operating Circuits; added
MAX20029BATIC/V+ and MAX20029CATIA/V+ to the Selector Guide and Ordering
Information tables as future parts
1–16
4
9/18
Updated General Description, Electrical Characteristics table, Soft-Start, and Output
Capacitor. Added MAX20029ATID/V+**, MAX20029BATID/V+**, MAX20029CATIB/
V+** with the accompanying ordering information to the Selector Guide
1, 4, 5, 10, 12,
15
5
9/18
Updated Electrical Characteristics table
DESCRIPTION
—
15
4
Replaced missing rows from bottom of Electrical Characteristics table and
future product and Ordering Information footnotes under the Selector Guide, which
were omitted in error
5.1
6, 7, 16
5, 16
6
10/18
Added MAX20029BATIE/V+** with the accompanying ordering information and
removed future product status from MAX20029CATIA/V+ in the Selector Guide
16
7
1/19
Removed future product status from MAX20029BATID/V+ and MAX20029CATIB/V+,
updated CH1 for MAX20029CATIB/V+, and corrected DC-DC Voltages note in the
Selector Guide
16
8
2/19
Removed future product status from MAX20029ATID/V+, MAX20029BATIB/V+ and
MAX20029BATIC/V+ in the Selector Guide
16
9
3/19
Added MAX20029ATIF/V+ in the Selector Guide
16
10
12/19
Added MAX20029D in the General Description and Benefits and Features, updated
Electrical Characteristics table, added MAX20029D in the Pin Description table,
Detailed Description and Soft-Start section, updated Inductor Selection, added
MAX20029D in the Typical Operating Circuits diagram, Updated Selector Guide and
Ordering Information tables by adding new row for MAX20029D
11
2/20
Added MAX20029CATIC/V+** and updated MAX20029DATIA/V+ in Ordering
Information
1, 3–6, 8, 11,
13, 15-16
16
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
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 specifications 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.
© 2019 Maxim Integrated Products, Inc. │ 17
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