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MAX16936

36V, 220kHz to 2.2MHz Step-Down Converter

with 28µA Quiescent Current

General Description

The MAX16936 is a 2.5A current-mode step-down con-

verter with integrated high-side and low-side MOSFETs

designed to operate with an external Schottky diode

for better efficiency. The low-side MOSFET enables

fixed-frequency forced-PWM (FPWM) operation under

light-load applications. The device operates with input

voltages from 3.5V to 36V, while using only 28FA qui-

escent current at no load. The switching frequency is

resistor programmable from 220kHz to 2.2MHz and can

be synchronized to an external clock. The MAX16936’s

output voltage is available as 5V/3.3V fixed or adjustable

from 1V to 10V. The wide input voltage range along with its

ability to operate at 98% duty cycle during undervoltage

transients make the MAX16936 ideal for automotive and

industrial applications.

Under light-load applications, the FSYNC logic input

allows the MAX16936 to either operate in skip mode for

reduced current consumption or fixed-frequency FPWM

mode to eliminate frequency variation to minimize EMI.

Fixed-frequency FPWM mode is extremely useful for

power supplies designed for RF transceivers where tight

emission control is necessary. Protection features include

cycle-by-cycle current limit and thermal shutdown with

automatic recovery. Additional features include a power-

good monitor to ease power-supply sequencing and a

180N out-of-phase clock output relative to the internal

oscillator at SYNCOUT to create cascaded power sup-

plies with multiple MAX16936s.

The MAX16936 operates over the -40NC to +125NC

automotive temperature range and is available in 16-pin

TSSOP-EP and 5mm x 5mm, 16-pin TQFN-EP packages.

42V Load Dump Protection

Enhanced Current-Mode Control Architecture

Fixed Output Voltage with ±2% Accuracy (5V/3.3V)

or Externally Resistor Adjustable (1V to 10V)

220kHz to 2.2MHz Switching Frequency with Three

Operation Modes



28µA Ultra-Low Quiescent Current Skip Mode



Forced Fixed-Frequency Operation



External Frequency Synchronization

Spread-Spectrum Frequency Modulation

Automatic LX Slew Rate Adjustment for Optimum

Efficiency Across Operating Frequency Range

180° Out-of-Phase Clock Output at SYNCOUT

Low-BOM-Count Current-Mode Control

Architecture

Power-Good Output

Enable Input Compatible from 3.3V Logic Level

to 42V

Thermal Shutdown Protection

-40°C to +125°C Automotive Temperature Range

AEC-Q100 Qualified

Features

Wide 3.5V to 36V Input Voltage Range

Applications

Point of Load Applications

Distributed DC Power Systems

Navigation and Radio Head Units

Ordering Information/Selector Guide

appears at end of data

sheet.

Typical Application Circuit

appears at end of data sheet.

For related parts and recommended products to use with this part, refer to:

www.maximintegrated.com/MAX16936.related

For pricing, delivery, and ordering information, please contact Maxim Direct at

1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

19-6626; Rev 1; 4/13

MAX16936

36V, 220kHz to 2.2MHz Step-Down Converter

with 28µA Quiescent Current

ABSOLUTE MAXIMUM RATINGS

SUP, SUPSW, LX, EN to PGND ............................-0.3V to +42V

SUP to SUPSW .....................................................-0.3V to +0.3V

BIAS to AGND .........................................................-0.3V to +6V

SYNCOUT, FOSC, COMP, FSYNC,

PGOOD,

FB to AGND ........................ -0.3V to (V

BIAS

+ 0.3V)

OUT to PGND ........................................................-0.3V to +12V

BST to LX.................................................................-0.3V to +6V

AGND to PGND ...................................................-0.3V to + 0.3V

LX Continuous RMS Current ...................................................3A

*As per JEDEC51 standard (multilayer board).

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-

tion 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.

Output Short-Circuit Duration ....................................Continuous

Continuous Power Dissipation (T

= +70NC)*

TSSOP (derate 26.1mw/NC above +70NC) .............2088.8mW

TQFN (derate 28.6mw/NC above +70NC) ...............2285.7mW

Operating Temperature Range ........................ -40NC to +125NC

Junction Temperature .....................................................+150NC

Storage Temperature Range............................ -65NC to +150NC

Lead Temperature (soldering, 10s) ................................+300NC

Soldering Temperature (reflow) ......................................+260NC

PACKAGE THERMAL CHARACTERISTICS (Note 1)

TSSOP

Junction-to-Ambient Thermal Resistance (B

) .......38.3NC/W

Junction-to-Case Thermal Resistance (B

) .................3NC/W

TQFN

Junction-to-Ambient Thermal Resistance (B

) .......... 35

C/W

Junction-to-Case Thermal Resistance (B

) ..............2.7NC/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.

ELECTRICAL CHARACTERISTICS

SUP

= V

SUPSW

= 14V, V

= 14V, L1 = 2.2FH, C

= 4.7FF, C

OUT

= 22FF, C

BIAS

= 1FF, C

BST

= 0.1FF, R

FOSC

= 12kI,

= T

= -40NC to +125NC, unless otherwise noted. Typical values are at T

= +25NC.)

PARAMETER

Supply Voltage

Load Dump Event Supply

Voltage

Supply Current

Shutdown Supply Current

BIAS Regulator Voltage

BIAS Undervoltage Lockout

Hysteresis

Thermal Shutdown Threshold

Hysteresis

OUTPUT VOLTAGE (OUT)

FPWM Mode Output Voltage

OUT

= V

BIAS,

6V < V

SUPSW

< 36V,

fixed-frequency mode (Note 2)

4.9

5.1

SYMBOL

SUP,

SUPSW

SUP_LD

SUP_STANDBY

SHDN

BIAS

UVBIAS

< 1s

Standby mode, no load, V

OUT

= 5V,

FSYNC

= 0V

SUP

= V

SUPSW

= 6V to 42V,

BIAS

= 0 to 10mA

BIAS

rising

4.7

2.95

3.15

450

+175

CONDITIONS

MIN

3.5

TYP

MAX

5.4

3.40

650

UNITS

Maxim Integrated

MAX16936

36V, 220kHz to 2.2MHz Step-Down Converter

with 28µA Quiescent Current

ELECTRICAL CHARACTERISTICS (continued)

SUP

= V

SUPSW

= 14V, V

= 14V, L1 = 2.2FH, C

= 4.7FF, C

OUT

= 22FF, C

BIAS

= 1FF, C

BST

= 0.1FF, R

FOSC

= 12kI,

= T

= -40NC to +125NC, unless otherwise noted. Typical values are at T

= +25NC.)

PARAMETER

Skip Mode Output Voltage

Load Regulation

Line Regulation

BST_ON

BST Input Current

LX Current Limit

LX Rise Time

Skip Mode Current Threshold

Spread Spectrum

High-Side Switch

On-Resistance

High-Side Switch Leakage

Current

Low-Side Switch

On-Resistance

Low-Side Switch

Leakage Current

TRANSCONDUCTANCE AMPLIFIER (COMP)

FB Input Current

FB Regulation Voltage

FB Line Regulation

Transconductance

(from FB to COMP)

Minimum On-Time

Maximum Duty Cycle

OSCILLATOR FREQUENCY

Oscillator Frequency

EXTERNAL CLOCK INPUT (FSYNC)

External Input Clock

Acquisition time

External Input Clock

Frequency

External Input Clock High

Threshold

Maxim Integrated

SYMBOL

OUT_SKIP

CONDITIONS

No load, V

= V

BIAS,

skip mode (Note 3)

= V

BIAS

, 300mA < I

LOAD

< 2.5A

= V

BIAS

, 6V < V

SUPSW

< 36V

High-side MOSFET on, V

BST

- V

= 5V

High-side MOSFET off, V

BST

- V

= 5V,

= +25°C

Peak inductor current

FOSC

= 12kW

= +25°C

Spread spectrum enabled

MIN

4.9

TYP

0.5

0.02

MAX

5.15

UNITS

%/V

1.5

BST_OFF

SKIP_TH

150

3.75

300

OSC

Q6%

100

1.5

4.5

400

ON_H

= 1A, V

BIAS

= 5V

High-side MOSFET off, V

SUP

= 36V,

= 0V, T

= +25NC

220

ON_L

= 0.2A, V

BIAS

= 5V

= 36V, T

= +25NC

LINE

ON_MIN

MAX

FOSC

= 73.2kI

FOSC

= 12kI

340

2.0

FB connected to an external resistor

divider, 6V < V

SUPSW

< 36V (Note 4)

6V < V

SUPSW

< 36V

= 1V, V

BIAS

= 5V

(Note 3)

0.99

1.0

0.02

700

400

2.2

100

1.015

%/V

460

2.4

kHz

MHz

FSYNC

FOSC

= 12kI (Note 5)

FSYNC_HI

FSYNC

rising

1.8

1.4

2.6

Cycles

MAX16936

36V, 220kHz to 2.2MHz Step-Down Converter

with 28µA Quiescent Current

ELECTRICAL CHARACTERISTICS (continued)

SUP

= V

SUPSW

= 14V, V

= 14V, L1 = 2.2FH, C

= 4.7FF, C

OUT

= 22FF, C

BIAS

= 1FF, C

BST

= 0.1FF, R

FOSC

= 12kI,

= T

= -40NC to +125NC, unless otherwise noted. Typical values are at T

= +25NC.)

PARAMETER

External Input Clock Low

Threshold

Soft-Start Time

ENABLE INPUT (EN)

Enable Input High Threshold

Enable Input Low Threshold

Enable Threshold Voltage

Hysteresis

Enable Input Current

POWER GOOD (PGOOD)

PGOOD

Switching Level

PGOOD

Debounce Time

PGOOD

Output Low Voltage

PGOOD

Leakage Current

SYNCOUT Low Voltage

SYNCOUT Leakage Current

FSYNC Leakage Current

OVERVOLTAGE PROTECTION

Overvoltage Protection

Threshold

Note

OUT

rising (monitored at FB pin)

OUT

falling (monitored at FB pin)

107

105

SINK

= 5mA

OUT

in regulation, T

= +25NC

SINK

= 5mA

= +25NC

TH_RISING

TH_FALLING

rising, V

PGOOD

= high

falling, V

PGOOD

=low

0.4

EN_HI

EN_LO

EN_HYS

= +25NC

0.2

0.1

2.4

0.6

SYMBOL

FSYNC_LO

CONDITIONS

FSYNC

falling

5.6

MIN

TYP

MAX

0.4

UNITS

Device not in dropout condition.

Guaranteed by design; not production tested.

FB regulation voltage is 1%, 1.01V (max), for -40°C < T

< +105°C.

Contact the factory for SYNC frequency outside the specified range.

Maxim Integrated

MAX16936

36V, 220kHz to 2.2MHz Step-Down Converter

with 28µA Quiescent Current

Typical Operating Characteristics

SUP

= V

SUPSW

= 14V, V

OUT

= 5V, V

FYSNC

= 0V, R

FOSC

= 12kI, T

= +25NC, unless otherwise noted.)

EFFICIENCY vs. LOAD CURRENT

MAX16936 toc01

EFFICIENCY vs. LOAD CURRENT

EFFICIENCY (%)

OUT

LOAD REGULATION

MAX16936 toc02

EFFICIENCY (%)

= 2.2MHz, V

= 14V

SKIP MODE

= 400kHz, V

= 14V

SKIP MODE

3.3V

PWM MODE

5.08

5.06

5.04

OUT

(V)

5.02

5.00

4.98

4.96

4.94

4.92

4.90

OUT

= 5V, V

= 14V

SKIP MODE

3.3V

PWM MODE

400kHz

2.2MHz

0.001

0.1

0.001

0.1

0.5

1.0

1.5

2.0

2.5

LOAD CURRENT (A)

LOAD

(A)

OUT

LOAD REGULATION

MAX16936 toc04

vs. LOAD CURRENT

MAX16936 toc05

vs. LOAD CURRENT

434

433

432

(MHz)

431

430

429

428

427

426

425

5.08

5.06

5.04

OUT

(V)

5.02

5.00

4.98

4.96

4.94

4.92

4.90

OUT

= 5V, V

= 14V

PWM MODE

2.28

2.26

2.24

(MHz)

2.22

2.20

2.18

2.16

2.14

2.12

2.10

VIN = 14V,

PWM MODE

OUT

= 5V

VIN = 14V,

PWM MODE

OUT

= 5V

400kHz

2.2MHz

OUT

= 3.3V

OUT

= 3.3V

0.5

1.0

1.5

2.0

2.5

0.5

1.0

1.5

2.0

2.5

0.5

1.0

1.5

2.0

2.5

LOAD

(A)

LOAD

(A)

LOAD

(A)

vs. TEMPERATURE

MAX16936 toc07

SWITCHING FREQUENCY vs. R

FOSC

MAX16936 toc08

SUPPLY CURRENT vs. SUPPLY VOLTAGE

SUPPLY CURRENT (µA)

MAX16936 toc09

2.28

2.24

2.20

(MHz)

2.16

2.12

2.08

2.04

2.00

= 14V,

PWM MODE

OUT

= 5V

2.50

2.25

SWITCHING FREQUENCY (MHz)

2.00

1.75

1.50

1.25

1.00

0.75

0.50

0.25

FOSC

(kΩ)

102

OUT

= 3.3V

-40 -25 -10 5 20 35 50 65 80 95 110 125

TEMPERATURE (°C)

132

5V/2.2MHz

SKIP MODE

SUPPLY VOLTAGE (V)

Maxim Integrated

MAX16936 toc06

5.10

2.30

435

MAX16936 toc03

100

5.10