MAX5068 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – High-Frequency, Current-Mode PWM Controller with Accurate Programmable Oscillator

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
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
Selector Guide appears at end of data sheet.
Pin Configurations
TOP VIEW
RT ₁
SYNC 2
HYST 3
DT 4
UVLO/EN 5
FB 6
COMP 7
FLTINT 8
MAX5068A/B
16 REG5
15 IN
14 V_CC
13 NDRV
12 AGND
11 PGND
10 AGND
9 CS
TSSOP-EP
Pin Configurations continued at end of data sheet.
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