MAX17595/MAX17596/MAX17597

Peak-Current-Mode Controllers for

Flyback and Boost Regulators

10

Maxim Integrated

Pin Description (continued)

Detailed Description

The MAX17595 offers a bootstrap UVLO wake-up level

of 20V with a wide hysteresis, and is optimized for imple-

menting isolated and nonisolated universal (85V to 265V

AC) offline single-switch flyback converter or telecom

(36V to 72V) power supplies. The MAX17596/MAX17597

offer a UVLO wake-up level of 4.4V and are well-suited

for low-voltage DC-DC flyback/boost power supplies. An

internal 1% reference (1.21V) can be used to regulate

the output in nonisolated flyback and boost applications.

Additional semiregulated outputs, if needed, can be gen-

erated by using additional secondary windings on the

flyback converter transformer.

The MAX17595/MAX17596/MAX17597 family utilizes

peak-current-mode control and external compensation

for optimizing closed-loop performance. The devices

include cycle-by-cycle peak current limit, and eight

consecutive occurrences of current-limit-event trigger

hiccup mode, which protects external components by

halting switching for a period of 32,768 cycles. .

The

MAX17595

has

no

limitation

on

maxi-

mum input voltage, as long as the external

components are rated suitably and the maximum

operating voltages of the MAX17595 are respected.

The MAX17595 implements a rising and falling UVLO

threshold that allows it to be successfully used in univer-

sal input (85V to 265V AC) rectified bus applications, in

rectified 3-phase DC bus applications, and in telecom

(36V to 72V DC) applications.

The MAX17596/MAX17597 are intended to implement

flyback (isolated and nonisolated) and boost convert-

maximum operating voltage of 36V. The MAX17596/

MAX17597 implement rising and falling thresholds on

typical of low-voltage DC-DC applications, down to

an input voltage of 4.5V DC. Therefore, flyback /boost

converters with a 4.5V to 36V supply voltage range can

be implemented with the MAX17596/MAX17597.

The internal functions and driver circuits are designed

to operate from 7.4V (MAX17595) or 5V (MAX17596/

MAX17597) power-supply voltages. The MAX17595/

MAX17596/MAX17597 family has an internal linear regu-

be decoupled with a 1FF capacitor to ground for stable

ating current of the MAX17595/MAX17596/MAX17597.

the MAX17595, and 36V for the MAX17596/MAX17597.

PIN

NAME

FUNCTION

13

close as possible to the IC.

14

a 1FF minimum ceramic capacitor.

15

EN/UVLO

Enable/Undervoltage Lockout. To externally program the UVLO threshold of the input supply,

connect a resistive divider between input supply, EN, and SGND.

16

OVI

Overvoltage Comparator Input. Connect a resistive divider between the input supply, OVI, and

SGND to set the input overvoltage threshold.

—

EP

Exposed Pad. Connect to a large ground plane through multiple vias to maximize thermal

dissipation.