MAX5021 Datasheet, PDF (1/11 Pages) Maxim Integrated Products – Current-Mode PWM Controllers for Isolated Power Supplies

19-2066; Rev 1; 9/01
EVALUATION
KIT
AVAILABLE
Current-Mode PWM Controllers for Isolated
Power Supplies
General Description
The MAX5021/MAX5022 current-mode PWM controllers
contain all the control circuitry required for the design
of wide input voltage range isolated power supplies.
These devices are well suited for use in universal input
(85VAC to 265VAC) off-line or telecom (-36VDC to
-72VDC) power supplies.
An undervoltage lockout (UVLO) circuit with large hys-
teresis coupled with low startup and operating current
reduce power dissipation in the startup resistor and
allow use of ceramic bypass capacitors. The 262kHz
switching frequency is internally trimmed to ±12%
accuracy; this allows the optimization of the magnetic
and filter components resulting in compact, cost-effec-
tive power supplies. The MAX5021 with 50% maximum
duty cycle and MAX5022 with 75% maximum duty
cycle are recommended for forward converters and fly-
back converters, respectively. The MAX5021/MAX5022
are available in 6-pin SOT23, 8-pin µMAX, and 8-pin
DIP packages and are rated for operation over the
-40°C to +85°C temperature range.
Applications
Universal Off-Line Power Supplies
Standby Power Supplies
Isolated Power Supplies
Isolated Telecom Power Supplies
Mobile Phone Chargers
Features
o Available in a Tiny 6-Pin SOT23 Package
o 50µA Typical Startup Current
o 1.2mA Typical Operating Current
o Large UVLO Hysteresis of 14V
o Fixed Switching Frequency of 262kHz ±12%
o 50% Maximum Duty Cycle Limit (MAX5021)
o 75% Maximum Duty Cycle Limit (MAX5022)
o 60ns Cycle-by-Cycle Current-Limit Response
Time
Ordering Information
PART
MAX
DUTY
CYCLE
TEMP.
RANGE
PIN-
TOP
PACKAGE MARK
MAX5021EUT
MAX5021EUA
MAX5021EPA
MAX5022EUT
MAX5022EUA
MAX5022EPA
50%
50%
50%
75%
75%
75%
-40°C to +85°C 6 SOT23-6 AASQ
-40°C to +85°C 8 µMAX
—
-40°C to +85°C 8 PDIP
—
-40°C to +85°C 6 SOT23-6 AASR
-40°C to +85°C 8 µMAX
—
-40°C to +85°C 8 PDIP
—
WARNING: The MAX5021/MAX5022 are designed to work
with high voltages. Exercise caution!
Typical Operating Circuit
V_SUPPLY
V_OUT
V_CC
V_IN
MAX5021
MAX5022
OPTO
NDRV
GND ^CS
Pin Configuration
TOP VIEW
CS 1
GND 2
NDRV 3
MAX5021
MAX5022
6 OPTO OPTO 1
5 V_IN
V_IN 2
V_CC 3
N.C. 4
4 V_CC
MAX5021
MAX5022
8 CS
7 GND
6 NDRV
5 N.C.
SOT23
PDIP/µMAX
________________________________________________________________ Maxim Integrated Products 1
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