Rainbow Electronics MAX5068 - Manual

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.
Applications
Universal-Input AC Power Supplies
Isolated Telecom Power Supplies
Networking System Power Supplies
Server Power Supplies
Industrial Power Conversion
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
High-Frequency, Current-Mode PWM Controller
with Accurate Programmable Oscillator
________________________________________________________________ Maxim Integrated Products 1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
RT REG5
IN
V CC
NDRV
AGND
PGND
AGND
CS
TOP VIEW
MAX5068A/B
TSSOP-EP
SYNC
HYST
FB
DT
UVLO/EN
COMP
FLTINT
Pin Configurations
Ordering Information
19-3176; Rev 0; 2/04
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.
*Future product—contact factory for availability.
**EP = Exposed pad.
PART TEMP RANGE PIN-PACKAGE
MAX5068AAUE* -40°C to +125°C 16 TSSOP-EP**
MAX5068BAUE -40°C to +125°C 16 TSSOP-EP**
MAX5068CAUE -40°C to +125°C 16 TSSOP-EP**
MAX5068DAUE* -40°C to +125°C 16 TSSOP-EP**
MAX5068EAUE* -40°C to +125°C 16 TSSOP-EP**
MAX5068FAUE* -40°C to +125°C 16 TSSOP-EP**
Pin Configurations continued at end of data sheet.
Selector Guide appears at end of data sheet.