MAX16936

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

with 28µA Quiescent Current

9

Maxim Integrated

Pin Descriptions (continued)

Detailed Description

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

converter 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 quiescent current at no

load. The switching frequency is resistor programmable

from 220kHz to 2.2MHz and can be synchronized to an

external clock. The 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 device ideal for

automotive and industrial applications.

Under light-load applications, the FSYNC logic input

allows the device 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, overvoltage protection, and

thermal shutdown with automatic recovery. Additional fea-

tures include a power-good monitor to ease power-supply

sequencinganda180Nout-of-phaseclockoutputrelativetothe

internal oscillator at SYNCOUT to create cascaded power

supplies with multiple devices.

Wide Input Voltage Range

The device includes two separate supply inputs (SUP and

SUPSW) specified for a wide 3.5V to 36V input voltage

provides power to the internal switch. When the device

is operating with a 3.5V input supply, conditions such as

cold crank can cause the voltage at SUP and SUPSW to

drop below the programmed output voltage. Under such

conditions, the device operates in a high duty-cycle mode

to facilitate minimum dropout from input to output.

Linear Regulator Output (BIAS)

The device includes a 5V linear regulator (BIAS) that pro-

vides power to the internal circuit blocks. Connect a 1FF

ceramic capacitor from BIAS to AGND.

Power-Good Output (PGOOD)

The device features an open-drain power-good output,

drops below 92% of its regulation voltage. Connect

PGOOD to BIAS with a 10kI resistor.

PIN

NAME

FUNCTION

TSSOP

TQFN

10

9

EN

SUP Voltage Compatible Enable Input. Drive EN low to disable the device. Drive EN high

to enable the device.

11

10

SUP

Voltage Supply Input. SUP powers up the internal linear regulator. Bypass SUP to PGND

with a 4.7FF ceramic capacitor.

12

11

SUPSW

Internal High-Side Switch Supply Input. SUPSW provides power to the internal switch.

Bypass SUPSW to PGND with 0.1FF and 4.7FF ceramic capacitors.

13, 14

12, 13

LX

Inductor Switching Node. Connect a Schottky diode between LX and AGND.

15

14

PGND

Power Ground

16

15

PGOOD

—

—

EP

Exposed Pad. Connect EP to a large-area contiguous copper ground plane for effective

power dissipation. Do not use as the only IC ground connection. EP must be connected

to PGND.