EVALUATION KIT AVAILABLE
Click here for production status of specific part numbers.
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
General Description
The MAX2501/MAX25202 are high-performance, currentmode PWM controllers with 1.5μA (typ) shutdown current for wide input voltage range boost converters. The
4.5V to 36V input operating voltage range makes these
devices ideal in automotive applications, such as frontend preboost or general-purpose boost power supply, for
the first boost stage in high-power LED lighting applications or to generate audio amplifier voltages. An internal
low-dropout regulator with a 5V output voltage enables
the MAX25201/MAX25202 to operate directly from an
automotive battery input. The input operating range can
be extended to as low as 1.8V after startup.
The MAX25201/MAX25202’s switching frequency operation (up to 2.2MHz) reduces output ripple, avoids AM band
interference, and allows for the use of smaller external
components. The switching frequency is resistor adjustable from 220kHz to 2.2MHz. Alternatively, the frequency
can be synchronized to an external clock. A spreadspectrum option is available to improve system EMI performance. For high-current applications the dual-phase
MAX25202 is available. The MAX25202 operates at a
fixed 400kHz switching frequency and can be synchronized to an external clock.
The controllers feature a power-OK monitor and undervoltage lockout. Protection features include cycle-bycycle current limit and thermal shutdown. The MAX25201/
MAX25202 operate over the -40°C to +125°C automotive
temperature range.
Applications
Infotainment Systems
Cluster Systems
E-Call
19-100588; Rev 3; 2/20
Benefits and Features
● Meets Stringent OEM Module Power Consumption
and Performance Specifications
• 20µA Quiescent Current in Skip Mode
• ±1.5% FB Voltage Accuracy
• Output Voltage Range: Fixed or Adjustable
Between 3.5V and 60V
● Enables Crank-Ready Designs
• Operates Down to 1.8V After Startup
• Wide Input Supply Range from 4.5V to 36V
● EMI Reduction Features Reduce Interference with
Sensitive Radio Bands Without Sacrificing Wide Input
Voltage Range
• Spread-Spectrum Option
• Frequency-Synchronization Input
• Resistor-Programmable Frequency Between
200kHz and 2.2MHz
● Integration and Thermally Enhanced Packages Save
Board Space and Cost
• Current-Mode Controllers with Forced-Continuous
and Skip Modes
• Thermally Enhanced 16-Pin TQFN-EP Package
● Protection Features Improve System Reliability
• Supply Undervoltage Lockout
• Overtemperature and Short-Circuit Protection
Ordering Information appears at end of data sheet.
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Simplified Block Diagram
PGOOD
SS
COMP
EN
FB
THRES
SOFT START
EAMP
REF
BST
SUP
BIAS
EN
OUT
DH
BIAS LDO
SUP
GATE
DRIVE
PWM
CSA
PWM
LX
CS
ILIM
ZX
ILIM THRES
DL
LX
SLOPE COMP
LOGIC
GND
ZERO CROSS
FOSC
OSCILLATOR
SPS OTP
MODE/
FSYNC
FSYNC
SELECT
LOGIC
www.maximintegrated.com
(SKIP MODE )
(PWM MODE )
Maxim Integrated │ 2
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Absolute Maximum Ratings
SUP, EN to GND......................................................-0.3V to 42V
OUT, FB, LX to GND................................................-0.3V to 65V
SUP to CS...............................................................-0.3V to 0.3V
BIAS, MODE/FSYNC, PGOOD, SS to GND..............-0.3V to 6V
DL, FOSC, COMP to GND......................... -0.3V to BIAS + 0.3V
BST to LX...................................................................-0.3V to 6V
DH to LX.........................................................-0.3V to BST+0.3V
Continuous Power Dissipation
TQFN (derate 28.8mW/°C* above +70°C).................1666mW
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
Lead Temperature (soldering, 10s).................................. +300°C
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.
Recommended Operating Conditions
PARAMETER
SYMBOL
CONDITION
Ambient Temperature
Range
TYPICAL RANGE
UNIT
-40 to 125
°C
Note: These limits are not guaranteed.
Package Information
TQFN
Package Code
T1633Y+5C
Outline Number
21-100150
Land Pattern Number
90-100064
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
44.5°C/W
Junction to Case (θJC)
5°C/W
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 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.
www.maximintegrated.com
Maxim Integrated │ 3
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Electrical Characteristics
(VSUP = 14V, VEN = 14V, CBIAS = 1μF, CBST = 0.1μF, TJ = -40°C to +150°C, unless otherwise noted. Typical values are at TA =
+25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
STEP UP CONTROLLER
Supply Voltage Range
VSUP
Output Over-Voltage
Threshold
Supply Current
Fixed Output Voltage
4.5
36
Operation after initial startup condition is satisfied
1.8
36
Detected with respect to VFB rising
IIN
VOUT
Output Voltage
Adjustable Range
Regulated Feedback
Voltage
VFB
Feedback Leakage
Current
IFB
Feedback Line
Regulation Error
Transconductance
(from FB to COMP)
Initial startup, VOUT = VBATT
gm_boost
Dead Time
102.0
105
107.5
VEN = VSUP, VFB = VBIAS (fixed output voltage),
VSUP > VOUT, no load (MAX25201)
25
VEN = VSUP, VSUP > VOUT, adjustable output, no
load. Excludes current through external FB divider
(MAX25201)
20
Shutdown, VEN = 0V, fixed output voltage
1.5
3
Shutdown, VEN = 0V, adjustable output, excludes
current through external FB divider
1.5
3
V
%
µA
VFB = VBIAS, PWM mode, MAX25201ATEA/VY+
and MAX25201ATEB/VY+ only
9.85
10.04
10.25
VFB = VBIAS, skip mode, MAX25201ATEA/VY+
and MAX25201ATEB/VY+ only
9.70
10.04
10.30
MAX25201ATEA/VY+ and MAX25201ATEB/VY+
3.5
36
MAX25201ATEC/VY+, MAX25201ATED/
VY+, MAX25202MATEA/VY+,
MAX25202SATEA/VY+
20
60
V
0.99
V
1.005
1.02
V
TA = 25°C
0.01
1
µA
VIN = 3.5V to 36V, VFB = 1V
0.01
VFB = 1V, VBIAS = 5V (Note 1)
165
250
DL low to DH rising
20
DH low to DL rising
20
%/V
345
µS
ns
DH Pullup Resistance
VBIAS = 5V, IDH = -100mA
1.5
2.6
Ω
DH Pulldown
Resistance
VBIAS = 5V, IDH = 100mA
1
2
Ω
DL Pullup Resistance
VBIAS = 5V, IDL = -100mA
1.5
2.8
Ω
DL Pulldown
Resistance
VBIAS = 5V, IDL = 100mA
1
2
Ω
Minimum Off Time
tOFFBST
PWM Switching
Frequency Range
fSW
Switching Frequency
Accuracy
www.maximintegrated.com
80
ns
MAX25201, programmable with RFOSC
0.22
2.2
RFOSC = 70kΩ, VBIAS = 5V, 3.3V (MAX25201)
380
400
420
MAX25202M/MAX25202S
375
400
425
MHz
kHz
Maxim Integrated │ 4
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Electrical Characteristics (continued)
(VSUP = 14V, VEN = 14V, CBIAS = 1μF, CBST = 0.1μF, TJ = -40°C to +150°C, unless otherwise noted. Typical values are at TA =
+25°C.) (Note 2)
PARAMETER
SYMBOL
CS Current-Limit
Voltage Threshold
VLIMIT
Soft-Start Current
Source
ISS
LX Leakage Current
PGOOD Threshold
CONDITIONS
VSUP - VCS; VBIAS =
5V, VSUP > 2.5V
MIN
TYP
MAX
UNITS
MAX25201
40
50
60
MAX25202M/S
36
48
60
8
10
12
µA
0.001
5
µA
VBIAS = 5V
VLX = VPGND or VSUP, TA = 25°C
PGOOD_H
% of VFB, rising
92.5
94.5
96.5
PGOOD_F
% of VFB, falling
90.5
92.5
94.5
mV
%
PGOOD Leakage
Current
VPGOOD = 5V, TA = 25°C
PGOOD Output Low
Voltage
IPGOOD = 1mA
PGOOD Debounce
Time
Fault detection, rising and falling
150
µs
PGOOD Timeout
Output in regulation to PGOOD high
1.5
ms
1
µA
0.2
V
FSYNC INPUT
FSYNC Frequency
Range
FSYNC Switching
Thresholds
Minimum sync pulse of 100ns, fOSC = 2.2MHz
1.8
2.6
MHz
Minimum sync pulse of 100ns, fOSC = 400kHz
250
550
kHz
High threshold
1.4
Low threshold
0.4
V
INTERNAL LDO BIAS
Internal BIAS Voltage
BIAS UVLO Threshold
Minimum Current
Capability
VIN > 6V
5
VBIAS rising
VBIAS falling
3.1
2.4
V
3.25
2.6
V
VBIAS = 5V
150
mA
Thermal Shutdown
Temperature
(Note 1)
170
°C
Thermal Shutdown
Hysteresis
(Note 1)
20
°C
THERMAL OVERLOAD
EN LOGIC INPUT
High Threshold
1.8
V
Low Threshold
EN Input Bias Current
EN logic inputs only, TA = 25°C
0.01
0.8
V
1
µA
SPREAD SPECTRUM
Spread Spectrum
fOSC ±
6%
Note 1: Limits are 100% tested at +25°C. Limits over operating temperature range and relevant supply voltage are guaranteed by
design and characterization. Typical values are at +25°C.
Note 2: The device is designed for continuous operation up to TJ = +125°C for 95,000 hours and TJ = +150°C for 5,000 hours.
www.maximintegrated.com
Maxim Integrated │ 5
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Typical Operating Characteristics
(VSUP = 14V, TA = 25°C, unless otherwise noted.)
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
toc01
24.5
8.16
24.4
OUTPUT VOLTAGE (V)
24
2A LOAD
23.9
4A LOAD
23.8
23.7
23.5
4
8
12
16
20
8.04
8
4A LOAD
7.96
7.84
24
3
4
5
6
7
70
50
8
95
EFFICIENCY (%)
5V INPUT
85
3V INPUT
0
1
75
70
5
4
6
toc06
100
95
21V INPUT
14V INPUT
21V INPUT
4.5V INPUT
CURRENT
LIMIT
85
3
2
MAX25201 EFFICIENCY
vs. LOAD CURRENT
toc05
14V INPUT
90
8V OUT
2.1MHz FPWM
RCS = 3mΩ
LOAD CURRENT (A)
100
90
EFFICIENCY (%)
CURRENT
LIMIT
75
55
MAX25201 EFFICIENCY
vs. LOAD CURRENT
toc04
7V INPUT
80
80
INPUT VOLTAGE (V)
MAX25201 EFFICIENCY
vs. LOAD CURRENT
95
3V INPUT
60
INPUT VOLTAGE (V)
100
5V INPUT
85
65
7.92
7.88
400kHz FPWM
24V OUTPUT
23.6
90
EFFICIENCY (%)
OUTPUT VOLTAGE (V)
24.1
toc03
7V INPUT
95
0A LOAD
8.08
0A LOAD
24.2
100
2.1MHz FPWM
8V OUTPUT
8.12
24.3
MAX25201 EFFICIENCY
vs. LOAD CURRENT
toc02
EFFICIENCY (%)
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
90
4.5V INPUT
CURRENT
LIMIT
85
65
60
55
50
RCS = 3mΩ
0
1
2
3
4
80
80
8V OUT
2.1MHz
SKIP
24V OUT
400kHz FPWM
RCS = 1.5mΩ
75
5
6
0
1
2
3
4
5
6
7
24V OUT
400kHz
SKIP
RCS = 1.5mΩ
75
8
0
2
1
3
4
5
6
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
OUTPUT VOLTAGE
vs. LOAD CURRENT
OUTPUT VOLTAGE
vs. LOAD CURRENT
QUIESCENT CURRENT
vs. SUPPLY VOLTAGE
toc07
8.15
toc08
24.5
7
8
toc09
50
24.4
24.3
5V INPUT
8.05
8
3V INPUT
7.95
7.9
7.85
8V OUT
2.1MHz FPWM
0
0.5
1
1.5
2
2.5
LOAD CURRENT (A)
www.maximintegrated.com
3
3.5
21V INPUT
24.1
24
4.5V INPUT
23.9
23.8
23.7
23.5
30
20
10
24V OUT
400kHz FPWM
23.6
4
40
14V INPUT
24.2
SUPPLY CURRENT (uA)
7V INPUT
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
8.1
0
0
0.5
1
1.5
2
2.5
LOAD CURRENT (A)
3
3.5
4
VFB = 1.15V
6
12
18
24
30
36
SUPPLY VOLTAGE (V)
Maxim Integrated │ 6
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Typical Operating Characteristics (continued)
(VSUP = 14V, TA = 25°C, unless otherwise noted.)
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
4
COLD-CRANK INPUT
VOLTAGE TRANSIENT
toc11
toc10
8V/div
VSUP
3.5
SUPPLY CURRENT (uA)
3
2.5
0V
10V/div
VOUT
2
0V
1.5
VPGOOD
1
0.5
0
5V/div
0V
5V/div
VBIAS
0V
0
4
8
12
16
20
24
28
32
36
50ms/div
SUPPLY VOLTAGE (V)
INPUT UNDERVOLTAGE PULSE
SUPPLY VOLTAGE RAMP
toc12
toc13
10V/div
VSUP
10V/div
0V
0V
VOUT
10V/div
10V/div
VSUP
VOUT
VPGOOD
0V
0V
5V/div
5V/div
0V
VPGOOD
0V
5V/div
VBIAS
0V
5V/div
VBIAS
0V
5s/div
500ms/div
POWER-UP RESPONSE
POWER-UP RESPONSE
toc14
10V/div
VSUP
10V/div
VSUP
0V
12V/div
VOUT
0V
12V/div
VOUT
0V
0V
5V/div
VPGOOD
0V
5V/div
VPGOOD
0V
5V/div
VBIAS
0V
3ms/div
www.maximintegrated.com
toc15
5V/div
VDL
0V
3ms/div
Maxim Integrated │ 7
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Typical Operating Characteristics (continued)
(VSUP = 14V, TA = 25°C, unless otherwise noted.)
STARTUP RESPONSE
STARTUP RESPONSE
toc16
toc17
10V/div
VSUP
10V/div
VSUP
0V
12V/div
VOUT
0V
12V/div
VOUT
0V
5V/div
VPGOOD
0V
0V
5V/div
VBIAS
0V
5V/div
VEN
0V
5V/div
VEN
SWITCHING WAVEFORM
LOAD TRANSIENT RESPONSE
toc18
10V/div
VSUP
0V
3ms/div
3ms/div
0V
10V/div
VSUP
0V
500mV/div
(AC)
VOUT
20V/div
VOUT
0V
14V/div
VLX
4A/div
0V
2A/div
ILOAD
0A
5µs/div
www.maximintegrated.com
12V/div
VOUT
0V
ILOAD
toc19
0A
1ms/div
Maxim Integrated │ 8
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Pin Configurations
MAX25202M
2
OUT
FB
12
DL
11
GND
3
10
BIAS
4
9
FOSC
7
8
MODE/
FSYNC
1
SUP
2
OUT
FB
16
15
14
13
+
12
DL
11
GND
3
10
BIAS
4
9
FSYNCOUT
MAX25202M
5
COMP
6
PGOOD
COMP
5
SS
MAX25201
CS
LX
LX
+
DH
DH
13
BST
BST
14
SW TQFN
3mm x 3mm
6
7
8
FSYNCIN
SUP
15
PGOOD
1
16
DUAL PHASE MASTER
TOP VIEW
SS
CS
EN
TOP VIEW
EN
MAX25201
SW TQFN
3mm x 3mm
MAX25202S
EN
BST
DH
LX
DUAL PHASE SLAVE
TOP VIEW
16
15
14
13
+
CS
1
SUP
2
OUT
3
10 BIAS
FB
4
9
6
7
8
NC
FSYNCINS
COMP
5
MODE
MAX25202S
SW TQFN
3mm x 3mm
www.maximintegrated.com
12
DL
11
GND
NC
Maxim Integrated │ 9
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Pin Description
PIN
MAX25201
1
MAX25202M
1
MAX25202S
1
NAME
CS
FUNCTION
Negative Current-Sense Input for Boost Controller. Connect CS to the
negative side of the current-sense element. See the Current Limiting
and Current-Sense Inputs (SUP and CS) and Current-Sense Resistor
Selection sections.
2
2
2
SUP
Supply Input and Positive Current-Sense Input for Boost Controller. Connect SUP to the positive terminal of the current-sense element. See the
Current Limiting and Current-Sense Inputs (SUP and CS) and Current
Sense Measurement sections.
3
3
3
OUT
Input for the BIAS LDO. Connect OUT to the boost output when the
output voltage is set at 24V or below. For VOUT greater than 24V,
connect OUT to the input supply.
4
4
4
FB
Boost Converter Feedback Input. To set the output voltage between
3.5V and 60V, connect FB to the center tap of a resistive divider between the boost regulator output. FB regulates to 1V (typ). To use the
factory set fixed output voltage on applicable parts (see the Ordering
Information section, connect FB to BIAS and connect OUT to the output.
For more information, see the Setting the Output Voltage section.
5
5
5
COMP
Boost Controller Error Amplifier Output. Connect a RC network to COMP
to compensate boost converter.
6
6
—
SS
—
—
6
MODE
7
7
—
PGOOD
—
—
7, 9
NC
Programmable Soft-Start. Connect a capacitor from SS to GND to set
the soft-start time. To select the value, see the Typical Operating Characteristics section.
Connect to FSYNCIN of the MAX25202M.
Open-Drain Power-Good Output for Buck Controller One. PGOOD goes
low if OUT drops below 92.5% (typ falling) of the normal regulation
point. PGOOD asserts low during soft-start and in shutdown. PGOOD
becomes high impedance when OUT is in regulation. To obtain a logic
signal, pull up PGOOD with an external resistor connected to a positive
voltage lower than 5.5V.
Do Not Connect
8
—
—
MODE/
FSYNC
External Clock Synchronization Input. To use the internal oscillator connect MODE/FSYNC high for forced-PWM or low for skip-mode operation. To synchronize with an external clock, connect the clock to MODE/
FSYNC. See the Light-Load Efficiency Skip Mode and Forced-PWM
Mode sections.
—
8
—
FSYNCIN
Synchronization Input. Connect to an external clock for synchronization.
Connect to ground for internal frequency setting. When an external
signal is connected, the spread spectrum is disabled.
—
—
8
FSYNCINS
Slave Input Synchronization. For dual-phase operation, connect FSYNCINS of the MAX25202S to FSYNCOUT of the MAX25202M.
9
—
—
FOSC
www.maximintegrated.com
Frequency Setting Input. Connect a resistor to FOSC to set the
switching frequency of the DC-DC converters.
Maxim Integrated │ 10
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Pin Description (continued)
PIN
MAX25201
MAX25202M
MAX25202S
—
9
—
10
10
NAME
FSYNCOUT
FUNCTION
Clock Synchronization Output. Connect FSYNCOUT to FSYNCINS of
the MAX25202S.
10
BIAS
5V Internal Linear Regulator Output. Bypass BIAS to GND with a lowESR ceramic capacitor of 1µF minimum value. BIAS provides the power
to the internal circuitry and external loads. See the Fixed 5V Linear
Regulator (BIAS) section.
Ground
11
11
11
GND
12
12
12
DL
Low-Side N-Channel MOSFET Gate Driver Output
13
13
13
LX
Inductor Connection for Boost Controller. Connect LX to the switched
side of the inductor. LX serves as the lower supply rail for the DH highside gate driver.
14
14
14
DH
High-Side MOSFET Gate Driver Output for Boost Controller. DH output
voltage swings from VLX to VBST.
15
15
15
BST
Boost Flying Capacitor Connection for High-Side Gate Voltage of Boost
Controller. Connect a high-voltage diode between BIAS and BST. Connect
a ceramic capacitor between BST and LX. See the High-Side GateDriver Supply (BST) section.
16
16
16
EN
High-Voltage Tolerant, Active-High Digital Enable Input for Controller
EP
Exposed Pad. Connect the exposed pad to ground. Connecting the
exposed pad to ground does not remove the requirement for proper
ground connections to 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.
—
—
www.maximintegrated.com
—
Maxim Integrated │ 11
MAX25201/MAX25202
Detailed Description
The MAX25201/MAX25202 automotive controller maintains regulation during cold crank or start-stop operations
down to a battery input of 1.8V, and operates with only
20μA IQ. The devices generate backlight voltages, audio
amplifier voltages, stand-alone preboost, as well as a
standby voltage in telematics applications. The devices
can start up with an input voltage supply from 3.5V to 42V
and can operate down to 1.8V after startup.
The MAX25201/MAX25202’s 2.2MHz switching frequency
reduces output ripple, avoids AM band interference, and
allows for the use of smaller external components. The
switching frequency is resistor adjustable from 220kHz to
2.2MHz. Alternatively, the frequency can be synchronized
to an external clock. A spread-spectrum option is available to improve system EMI performance.
These controllers feature a power-OK monitor as well as
overvoltage and undervoltage lockout. Protection features
include cycle-by-cycle current limit and thermal shutdown.
The MAX25201/MAX25202 are specified for operation
over the -40°C to +125°C automotive temperature range.
Current-Mode Control Loop
Peak current-mode control operation provides excellent
load step performance and simple compensation. The
inherent feed-forward characteristic is useful especially in
automotive applications where the input voltage changes
quickly during cold-crank and load dump conditions.
To avoid premature turn-off at the beginning of the on
cycle the current-limit and PWM comparator inputs have
leading-edge blanking.
Fixed 5V Linear Regulator (BIAS)
An internal 5V linear regulator (BIAS) is used to power
the controller's internal circuitry. Connect a 1μF or greater
ceramic capacitor from BIAS to GND as close as possible
to the IC pins to guarantee stability under the full-load
condition. The internal linear regulator can provide up to
150mA (typ) total. The internal bias current requirements
can be estimated as follows:
IBIAS = ICC + fSW (QG_DL + QG_DH)
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
The OUT pin is the input to the linear regulator. OUT is
typically connected to the boost output for applications
with the output voltage set to 24V or less and applications that require operation with a supply voltage below
5.2V. To reduce power dissipation in applications with
higher output voltages, OUT should be connected to
SUP. Bypass OUT with a 1µF or greater ceramic capacitor to GND.
Startup Operation/UVLO/EN
The BIAS undervoltage lockout (UVLO) circuitry inhibits
switching if the 5V bias supply (BIAS) is below its 2.6V
(typ) UVLO falling threshold. Once BIAS rises above its
UVLO rising threshold and EN is high, the boost controller
starts switching and the output voltage begins to ramp up
using soft-start. Driving EN low disables the device and
reduces the standby current to less than 10μA.
Soft-Start
Soft-start ramps up the internal reference during startup
to reduce input surge current. Connect a capacitor from
SS to GND to set the soft-start time. Select the capacitor
value as follows:
CSS [nF] = 10 × tss [ms]
Soft-start begins when EN is logic-high and VBIAS is
above the undervoltage lockout threshold.
Oscillator Frequency/External
Synchronization
The MAX25201's internal oscillator is set by a resistor
connected from FOSC to GND with an adjustment range
of 220kHz to 2.2MHz. High-frequency operation optimizes
the application for the smallest component size, trading
off efficiency to higher switching losses. Low-frequency
operation offers the best overall efficiency at the expense
of component size and board space.
FSW =
24500 +
√
RFOSC
0.006
RFOSC
where:
The MAX25202's internal oscillator is fixed at 400kHz.
ICC = the internal supply current
The devices can also be synchronized to an external
clock by connecting the external clock signal to MODE/
FSYNC (MAX25201) or FSYNCIN (MAX25202M). The
internal oscillator is synchronized on the rising edge of the
external clock. See the Electrical Characteristics table for
the FSYNC frequency range and voltage levels.
fSW = the switching frequency
QG_ = the low- and high-side MOSFET total gate charge
(specification limits at VGS = 5V).
To reduce the internal power dissipation, BIAS can optionally be connected to an external 5V rail, bypassing the
internal linear regulator.
www.maximintegrated.com
Maxim Integrated │ 12
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Light-Load Efficiency Skip Mode
voltage of the external MOSFETs. A low-resistance, lowinductance path from DL and DH to the MOSFET gates
is required in order for the protection circuits to work
properly.
In skip mode, once the output reaches regulation, the
MAX25201/MAX25202 stop switching until the FB voltage
drops below the reference voltage. Once the FB voltage
has dropped below the reference voltage, the devices
resume switching until the inductor current reaches 30%
(skip threshold) of the maximum current set by the inductor DCR or current-sense resistor.
High-Side Gate-Driver Supply (BST)
The skip mode feature of the MAX25201/MAX25202 is
used to improve light-load efficiency. Drive MODE/FSYNC
low to enable skip mode.
Forced-PWM Mode
Drive MODE/FSYNC of the MAX25201/MAX25202 high
(connect to BIAS) for forced-PWM operation. This prevents the devices from entering skip mode by disabling
the zero-crossing detection of the inductor current, and
forces the low-side gate-drive waveform to the complement of the high-side gate-drive waveform. Under lightload the inductor current reverses, discharging the output
capacitor. The benefit of forced-PWM mode is that it
keeps the switching frequency constant under all load
conditions. This reduces ripple and makes it predictable and easier to filter. Forced-PWM mode is useful
for improving load-transient response and eliminating
unknown frequency harmonics that can interfere with AM
radio bands. The disadvantage with forced-PWM operation is that it reduces light-load efficiency.
Forced-PWM is always used when synchronizing to an
external clock and in multiphase applications.
Spread Spectrum
Spread spectrum reduces peak emission noise at the
clock frequency and its harmonics, making it easier to
meet stringent EMI limits. This is done by dithering the
switching frequency ±6%. Using an external clock source
(i.e. driving the MODE/FSYNC input with an external
clock) disables spread spectrum.
Spread spectrum is a factory set option. See the Ordering
Information section to determine which part numbers
have spread spectrum enabled.
MOSFET Drivers (DH and DL)
The DH high-side n-channel MOSFET driver is powered from BST. The low-side driver (DL) is powered
from BIAS. To prevent a MOSFET from turning on before
a complementary switch is fully off, each driver has
shoot-through protection that monitors the gate-to-source
www.maximintegrated.com
The high-side MOSFET is turned on by closing an internal switch between BST and DH and transferring the
bootstrap capacitor’s (at BST) charge to the gate of the
high-side MOSFET. This charge refreshes when the highside MOSFET turns off and the LX voltage drops down
to ground potential, taking the negative terminal of the
capacitor to the same potential. The bootstrap diode then
recharges the positive terminal of the bootstrap capacitor.
The selected n-channel high-side MOSFET determines
the appropriate boost capacitance values according to the
following equation:
CBST = QG/∆VBST
where:
QG = the total gate charge of the high-side MOSFET
∆VBST = the voltage variation allowed on the highside MOSFET driver after turn-on. Choose ∆VBST such
that the available gate-drive voltage is not significantly
degraded (e.g., ∆VBST = 100mV to 300mV) when determining CBST. The boost capacitor should be a low-ESR
ceramic capacitor. A minimum value of 0.1μF works well
in most cases.
Current Limiting and Current-Sense Inputs
(SUP and CS)
The current-limit circuit uses differential current-sense
inputs (SUP and CS) to limit the peak inductor current.
If the magnitude of the current-sense signal exceeds the
current-limit threshold (VLIMIT > 50mV (typ)), the PWM
controller turns off the high-side MOSFET.
For the most accurate current sensing, use a currentsense resistor between the inductor and the input capacitor. Connect CS to the inductor side of RCS and SUP
to the capacitor side. See the Current-Sense Resistor
Selection section to determine the resistor value.
To improve efficiency, the current can also be measured
directly across the inductor, eliminating the power loss
from the sense resistor. However, this method is significantly less accurate and requires a filter network in
the current-sense circuit. See the Inductor DCR Current
Sense section for more information.
Maxim Integrated │ 13
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Voltage Monitoring (PGOOD)
PGOOD is the open-drain output of the output voltage
monitor. PGOOD is high impedance when the output
voltage is in regulation. PGOOD pulls low when the output voltage drops below the PGOOD threshold. See the
Electrical Characteristics table. Typically, a pullup resistor
is connected from PGOOD to the relevant logic rail to
provide a logic-level output. PGOOD asserts low during
soft-start and when disabled (EN is low).
Protection Features
Overcurrent Protection
If the inductor current exceeds the maximum current
limit set by RCS or inductor DCR sensing, the respective
MOSFET driver turns off. Increasing the output current
further results in shorter and shorter high-side pulses. A
hard short results in a minimum on-time pulse every clock
cycle. When required, choose components that can withstand the short-circuit current.
Thermal Overload Protection
Thermal-overload protection limits total power dissipation in the MAX25201/MAX25202. When the junction
temperature exceeds +170°C (typ), an internal thermal
sensor shuts the devices off, allowing them to cool down.
The thermal sensor turns the devices on again after the
junction temperature cools by 20°C (typ).
R1
Slope Compensation
The devices use an internal current-ramp generator for
slope compensation. The slope compensation for the
MAX25201A and MAX25201B is optimized for operation
with output voltage set to 36V or lower. The MAX25201C,
MAX25201D, and MAX25202 are optimized for output
voltages between 20V and 60V.
All versions of the MAX25201/MAX25202 support an
adjustable output voltage. See the Ordering Information
section for the adjustable output voltage range. To set the
output voltage, connect FB to the center a resistor divider
from the output to ground. Calculate the resistor values as
follows:
www.maximintegrated.com
VOUT
VFB
−1
]
Parts with a fixed output voltage option (see the Ordering
Information section) can also be used without the external
FB divider. To use the preset output voltage, connect FB
to BIAS, and connect OUT to the regulator output.
Inductor Selection
Duty cycle and frequency are important when calculating the inductor size because the inductor current ramps
up during the on-time of the switch and ramps down
during its off-time. A higher switching frequency generally improves transient response and reduces component
size; however, if the boost components are used as the
input filter components during non-boost operation, a low
frequency is advantageous.
The duty-cycle range of the boost converter depends on
the effective input-to-output voltage ratio. In the following
calculations, the duty cycle refers to the on-time of the
boost MOSFET:
DMAX =
VOUT(MAX) − VSUP(MIN)
VOUT(MAX)
or including losses in the inductor and high-side MOSFET
(VON,FET):
DMAX =
(
VOUT(MAX) − VSUP(MIN) + IOUT × (RDC + RHSRDSON)
VOUT(MAX)
)
The ratio of the inductor peak-to-peak AC current to DC
average current (LIR) must be selected first. A good initial
value is a 30% peak-to-peak ripple current to average
current ratio (LIR = 0.3). The switching frequency, input
voltage, output voltage, and selected LIR determine the
inductor value as follows:
VSUP × D
Applications Information
Setting the Output Voltage
[
R2
where R1 is the resistor connected from FB to the output,
R2 is the resistor connected from FB to ground, VOUT is
the desired output voltage, and VFB is the regulated feedback voltage (1.005V typ).
Overvoltage Protection
The devices limit the output voltage by turning off the
high-side gate driver if the output voltage exceeds 105%
(typ) of the nominal output voltage. The output voltage must come back into regulation before the devices
resume switching.
=
L[μH] = f
SW[MHz] × LIR
where:
D = (VOUT-VSUP)/VOUT
VSUP = Typical input voltage
VOUT = Typical output voltage
LIR = 0.3 x IOUT/(1-D)
Maxim Integrated │ 14
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Select the inductor with a saturation current rating higher
than the peak switch current limit of the converter:
IL_PEAK > IL_MAX +
∆ IL_RIP_MAX
2
Running a boost converter in continuous-conduction
mode introduces a right-half plane zero into the transfer
function. To avoid the effect of this right-half plane zero,
the crossover frequency for the control loop should be ≤
1/3 x fRHP_ZERO. If faster bandwith is required, a smaller
inductor and higher switching frequency is recommended.
Input Capacitor Selection
The input current for the boost converter is continuous
and the RMS ripple current at the input capacitor is low.
Calculate the minimum input capacitor value and the
maximum ESR using the following equations:
∆ IL × D
CSUP = 4 × f
SW × ∆ VQ
ESR =
∆ VESR
∆ IL
where:
∆ IL
(VSUP − VDS) × D
=
L × fSW
VDS is the total voltage drop across the external MOSFET
plus the voltage drop across the inductor ESR. ∆IL is the
peak-to-peak inductor ripple current as calculated above.
∆VQ is the portion of input ripple due to the capacitor
discharge and ∆VESR is the contribution due to ESR of
the capacitor. Assume the input capacitor ripple contribution due to ESR (∆VESR) and capacitor discharge (∆VQ)
are equal when using a combination of ceramic and aluminum capacitors. During the converter turn-on, a large
current is drawn from the input source, especially at high
output-to-input differential.
Output Capacitor Selection
enough to minimize the voltage drop while supporting the
load current. Use the following equations to calculate the
output capacitor for a specified output ripple. All ripple
values are peak-to-peak:
∆ VESR
ESR = I
OUT
IOUT × DMAX
C = ∆V ×f
Q SW
IOUT is the load current in A, fSW is in MHz, COUT is in
μF, ∆VQ is the portion of the ripple due to the capacitor
discharge, and ∆VESR is the contribution due to the ESR
of the capacitor. DMAX is the maximum duty cycle at the
minimum input voltage. Use a combination of low-ESR
ceramic and high-value, low-cost aluminum capacitors for
lower output ripple and noise.
Current-Sense Resistor Selection
The current-sense resistor (RCS), connected between the
battery and the inductor, sets the current limit. The CS
input has a voltage trip level (VCS) of 50mV (typ).
Set the current-limit threshold high enough to accommodate the component variations. Use the following equation to calculate the value of RCS:
VCS
RCS = I
SUP(MAX)
where IIN(MAX) is the peak current that flows through the
MOSFET at full load and minimum VIN.
ILOAD(MAX)
ISUP(MAX) = 1 − D
MAX
When the voltage produced by this current (through the
current-sense resistor) exceeds the current-limit comparator threshold, the MOSFET driver (DL) quickly terminates the on-cycle.
In a boost converter, the output capacitor supplies the
load current when the boost MOSFET is on. The required
output capacitance is high, especially at higher duty
cycles. Also, the output capacitor ESR needs to be low
www.maximintegrated.com
Maxim Integrated │ 15
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
BATTERY
L
RCS
CS
SUP
CURRENT SENSE RESISTOR
BATTERY
RDC
R2
L
R1
CEQ
CS
SUP
INDUCTOR DCR CURRENT SENSE
Figure 1. Current-Sense Configurations
Inductor DCR Current Sense
High-power applications that do not require accurate current sense can use the inductor's DC resistance as the
current sense element instead of the current-sense resistor. This is done by connecting an RC network across the
inductor. The equivalent sense resistance of the network
is:
(
R2
)
RCS_EQ = R1 + R2 × RDC
where RDC is the DC resistance of the inductor, R1 is
connected from the switch side of the inductor to CS, and
R2 is connected from the battery side of the inductor to
CS. The capacitor CEQ (connected parallel to R2) is calculated as follows:
L
(
1
1
CEQ = R
+
DC R1 R2
www.maximintegrated.com
)
Boost Converter Compensation
The basic regulator loop is modeled as a power modulator, output feedback-divider, and an error amplifier, as
shown in the Synchronous Boost Application Circuit. The
power modulator has a DC gain set by gmc x RLOAD, with
a pole and zero pair set by RLOAD, the output capacitor
(COUT), and its ESR. The loop response is set by the following equations:
(
)
1−D
GMOD = gMC × RLOAD × 2 ×
(
f
× 1 − jf
Rph_zMOD
)
( )
1+j
1+j
f
fzMOD
f
fpMOD
where RLOAD = VOUT/ILOUT(MAX) in Ω and gmc =1/
(AV_CS x RDC) in S. AV_CS is the voltage gain of the
current-sense amplifier and is typically 12V/V. RDC is the
DC resistance of the inductor or the current-sense resistor in Ω.
Maxim Integrated │ 16
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
In a current-mode step-down converter, the output capacitor and the load resistance introduce a pole at the following frequency:
1
fpMOD = π × R
LOAD × COUT
The output capacitor and its ESR also introduce a zero at:
1
fzMOD = 2π × ESR × C
OUT
The loop gain crossover frequency (fC) should be ≤ 1/3 of
right-half plane zero frequency.
fC ≤
fRph_zMOD = 2π × L × (1 − D) × (1 − D)
When COUT is composed of “n” identical capacitors in
parallel, the resulting COUT = n x COUT(EACH), and ESR
= ESR(EACH)/n. Note that the capacitor zero for a parallel combination of similar capacitors is the same as for an
individual capacitor.
The feedback voltage-divider has a gain of GAINFB =
VFB/VOUT, where VFB is 1.0V (typ).
3
At the crossover frequency, the total loop gain must be
equal to 1. So:
VFB
GAINMOD(f ) × V
× GAINEA(f ) = 1
C
C
OUT
GAINEA(f ) = gm, EA × RC
C
The right-half plane zero is at:
RLOAD
fRph_zMOD
GAINMOD(f ) = GAINMOD(dc) ×
C
fpMOD
fC
Therefore:
GAINMOD(f )
C
VFB
×V
× gm, EA × RC = 1
OUT
Solving for RC:
VOUT
RC = g
m, EA × VFB × GAINMOD(fC)
The transconductance error amplifier has a DC gain of
GAINEA(DC) = gm,EA x ROUT,EA, where gm,EA is the
error-amplifier transconductance, which is 345μS (max),
and ROUT,EA is the output resistance of the error amplifier, which is 10MΩ (typ). See the Electrical Characteristics
table.
Set the error-amplifier compensation zero formed by RC
and CC at the fpMOD. Calculate the value of CC as follows:
A dominant pole (fdpEA) is set by the compensation capacitor (CC) and the amplifier output resistance (ROUT,EA). A
zero (fZEA) is set by the compensation resistor (RC) and
the compensation capacitor (CC). There is an optional
pole (fPEA) set by CF and RC to cancel the output capacitor ESR zero if it occurs near the crossover frequency
(fC), where the loop gain equals 1 (0dB). Thus:
If fzMOD is less than 5 x fC, add a second capacitor (CF)
from COMP to GND. The value of CF is:
fpEA =
(
1
)
2π × ROUTEA + RC × CC
1
fzEA = 2π × R × C
C
C
1
fp2EA = 2π × R × C
C
F
www.maximintegrated.com
1
CC = 2π × f
pMOD × RC
1
CF = 2π × f
zMOD × RC
MOSFET Selection
The key selection parameters to choose the n-channel
MOSFET used in the boost converter are as follows.
Threshold Voltage
The boost n-channel MOSFETs must be a logic-level
type with guaranteed on-resistance specifications at VGS
= 4.5V.
Maxim Integrated │ 17
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Maximum Drain-to-Source Voltage (VDS(MAX))
The MOSFET must be chosen with an appropriate VDS
rating to handle all VIN voltage conditions.
Current Capability
The n-channel MOSFET must deliver the input current
(IIN(MAX)):
DMAX
IIN(MAX) = ILOAD(MAX) × 1 − D
MAX
Choose MOSFETs with the appropriate average current
at VGS = 4.5V.
Low Voltage Operation
The devices start with a supply voltage as low as 4.5V,
and can operate after initial start up with a supply voltage
as low as 1.8V. At very low input voltages it is important
to remember that input current will be high and the power
components (inductor, MOSFET, and diode) must be
specified for this higher input current.
In addition, the current-limit must be set high enough
so that the limit is not reached during the MOSFET's on
time, which would limit output power and eventually force
the MAX25201/MAX25202 into hiccup mode. Estimate
the maximum input current using the following equation:
VOUT × IOUT
ISUPMAX = η × V
+ 0.5 ×
SUPMIN
VOUT − VSUPMIN
VOUT
VSUPMIN
× f
SW × L
where ISUPMAX is the maximum input current; VOUT and
IOUT are the output voltage and current, respectively; η
is the estimated efficiency (which is lower at low input
voltages due to higher resistive losses); VSUPMIN is the
minimum value of the input voltage; fSW is the switching
frequency; and L is the minimum value of the chosen
inductor.
www.maximintegrated.com
Multiphase Operation
Dual-Phase (MAX25202)
Dual-phase operation uses a MAX25202M as the master controller and MAX25202S as the slave. Connect
these devices as shown in the Dual-Phase Application
Circuit. In this configuration, the master outputs a clock
from SYNCOUT that is 180° out-of-phase for driving the
slave FSYNCINS input. When synchronizing to an external clock, connect the clock to FSYNCIN of the master
and MODE of the slave. The external clock must have
50% duty-cycle to ensure the 180° phase shift. To use
the internal oscillator from the master, drive FSYNCIN
of the master and MODE of the slave high (connect
to BIAS). Dual-phase solutions allow spread spectrum
operation on both the master and slave.
Layout Recommendations
Careful PCB layout is critical to achieve low switching losses and clean, stable operation. Layout of the
switching power components requires particular attention.
Follow these guidelines for good PCB layout:
● Keep high-current paths short, especially at the
ground terminals.
● Minimize resistance in high-current paths by keeping
the traces short and wide. Using thick (2oz vs. 1oz
copper) improves full load efficiency.
● Connect the CS and SUP connections used for current sensing directly across the sense resistor using
a Kelvin sense connection.
● Route noisy switching and clock traces away from
sensitive analog areas (FB, CS).
Maxim Integrated │ 18
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Typical Application Circuits
Synchronous Boost Application Circuit
BATTERY I NPUT
3.5 V TO 36V
OUTPUT
BIAS
BST
LX
DL
MAX25201
CS
SUP
DH
OUT
EN
MODE/
FSYNC
FB
PGOOD
FOSC
SS
COMP
GND
www.maximintegrated.com
Maxim Integrated │ 19
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Typical Application Circuits (continued)
Dual-Phase Application Circuit
BATTERY INPUT
3.5V TO 36V
OUTPUT
BIAS
BST
LX
DL
MAX25202M
CS
EXTERNAL CLOCK
(OPTIONAL)
SUP
DH
OUT
FSYNCIN
FSYNCOUT
EN
FB
PGOOD
COMP
GND
SS
BIAS
BST
LX
DL
MAX25202S
CS
SUP
COMP
EN
DH
OUT
FB
FSYNCINS
MODE
GND
www.maximintegrated.com
Maxim Integrated │ 20
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Ordering Information
TEMP
RANGE
PINPACKAGE
V OUT
RANGE
FIXED
V OUT
INTERNAL
SWITCHING
FREQUENCY
SPREAD
SPECTRUM
TOPOLOGY
MAX25201ATEA/VY+
-40°C to
+125°C
16 SW
TQFN-EP*
3.5V to 36V
10
Adjustable
OFF
SINGLE
PHASE
MAX25201ATEB/VY+
-40°C to
+125°C
16 SW
TQFN-EP*
3.5V to 36V
10
Adjustable
ON
SINGLE
PHASE
MAX25201ATEC/VY+
-40°C to
+125°C
16 SW
TQFN-EP*
20V to 60V
N/A
Adjustable
OFF
SINGLE
PHASE
MAX25201ATED/VY+
-40°C to
+125°C
16 SW
TQFN-EP*
20V to 60V
N/A
Adjustable
ON
SINGLE
PHASE
MAX25202MATEA/VY+
-40°C to
+125°C
16 SW
TQFN-EP*
20V to 60V
N/A
400kHz
ON
2-PHASE
MASTER
MAX25202SATEA/VY+
-40°C to
+125°C
16 SW
TQFN-EP*
20V to 60V
N/A
400kHz
ON
2-PHASE
SLAVE
PART
*EP = Exposed pad.
www.maximintegrated.com
Maxim Integrated │ 21
MAX25201/MAX25202
36V HV Synchronous Boost Controller
for Automotive Infotainment Applications
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
7/19
Initial release
—
1
7/19
Updated Ordering Information section
21
2
12/19
Updated Electrical Chracteristics table and Ordering Information
3
2/20
Removed remaining future-product notation in Ordering Information
DESCRIPTION
4. 5, 21
21
For information on other Maxim Integrated products, visit Maxim Integrated’s website at www.maximintegrated.com.
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. │ 22
工商网监
湘ICP备2023018690号
