19-3176; Rev 1; 7/04
High-Frequency, Current-Mode PWM Controller
with Accurate Programmable Oscillator
General Description
The MAX5068 is a high-frequency, current-mode,
pulse-width modulation (PWM) controller that integrates
all the building blocks necessary for implementing AC-
DC or DC-DC fixed-frequency power supplies. Isolated
or nonisolated power supplies are easily constructed
using either primary- or secondary-side regulation.
Current-mode control with leading-edge blanking sim-
plifies control-loop design, and a programmable inter-
nal slope-compensation circuit stabilizes the current
loop when operating at duty cycles above 50%. The
MAX5068A/B limit the maximum duty cycle to 50% for
use in single-ended forward converters. The
MAX5068C/D/E/F allow duty cycles up to 75%. The
MAX5068 features an accurate externally programma-
ble oscillator that simplifies system design.
An input undervoltage lockout (UVLO) programs the
input-supply startup voltage and ensures proper opera-
tion during brownout conditions.
A single external resistor programs the output switching
frequency from 12.5kHz to 1.25MHz. The MAX5068A/
B/C/E provide a SYNC input for synchronization to an
external clock. The maximum FET-driver duty cycle is
50% for the MAX5068A/B and 75% for the MAX5068C/
D/E/F. Programmable hiccup current limit provides
additional protection under severe faults.
The MAX5068 is specified over the -40°C to +125°C
automotive temperature range and is available in a
16-pin thermally enhanced TSSOP-EP package. Refer to
the MAX5069 data sheet for dual FET-driver applications.
Warning:
The MAX5068 is designed to work with high
voltages. Exercise caution.
Features
♦
Current-Mode Control with 47µA (typ) Startup
Current
♦
Resistor-Programmable ±4.5% Accurate
Switching Frequency:
25kHz to 1.25MHz (MAX5068A/B)
12.5kHz to 625kHz (MAX5068C/D/E/F)
♦
Rectified 85V
AC
to 265V
AC
or 36V
DC
to 72V
DC
Input (MAX5068A/C/D)
♦
Input Directly Driven from 10.8V to 24V
(MAX5068B/E/F)
♦
Frequency Synchronization Input
(MAX5068A/B/C/E)
♦
Programmable Dead Time and Slope
Compensation
♦
Programmable Startup Voltage (UVLO)
♦
Programmable UVLO Hysteresis
(MAX5068A/B/D/F)
♦
Integrating Fault Protection (Hiccup)
♦
-40°C to +125°C Automotive Temperature Range
♦
16-Pin Thermally Enhanced TSSOP-EP Package
MAX5068
Ordering Information
PART
MAX5068AAUE
MAX5068BAUE
MAX5068CAUE
MAX5068DAUE
MAX5068EAUE
MAX5068FAUE
*EP
= Exposed pad.
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
16 TSSOP-EP*
16 TSSOP-EP*
16 TSSOP-EP*
16 TSSOP-EP*
16 TSSOP-EP*
16 TSSOP-EP*
Applications
Universal-Input AC Power Supplies
Isolated Telecom Power Supplies
Networking System Power Supplies
Server Power Supplies
Industrial Power Conversion
TOP VIEW
RT 1
SYNC 2
HYST 3
DT 4
UVLO/EN 5
FB 6
COMP 7
FLTINT 8
Pin Configurations
16 REG5
15 IN
14 V
CC
MAX5068A/B
13 NDRV
12 AGND
11 PGND
10 AGND
9
CS
Selector Guide appears at end of data sheet.
TSSOP-EP
Pin Configurations continued at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
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