MAXIM MAX5021, MAX5022 User Manual
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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 hysteresis 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-effective power supplies. The MAX5021 with 50% maximum
duty cycle and MAX5022 with 75% maximum duty
cycle are recommended for forward converters and flyback 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
♦ Available in a Tiny 6-Pin SOT23 Package
♦ 50µA Typical Startup Current
♦ 1.2mA Typical Operating Current
♦ Large UVLO Hysteresis of 14V
♦ Fixed Switching Frequency of 262kHz ±12%
♦ 50% Maximum Duty Cycle Limit (MAX5021)
♦ 75% Maximum Duty Cycle Limit (MAX5022)
♦ 60ns Cycle-by-Cycle Current-Limit Response
Time
MAX5021/MAX5022
Current-Mode PWM Controllers for Isolated
Power Supplies
________________________________________________________________ Maxim Integrated Products 1
Pin Configuration
Ordering Information
MAX5021
MAX5022
V
OUT
V
SUPPLY
OPTO NDRV
CS
V
CC
V
IN
GND
Typical Operating Circuit
19-2066; Rev 1; 9/01
EVALUATION KIT AVAILABLE
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.
WARNING: The MAX5021/MAX5022 are designed to work
with high voltages. Exercise caution!
MAX
PART
MAX5021EUT 50% -40°C to +85°C 6 SOT23-6 AASQ
MAX5021EUA 50% -40°C to +85°C 8 µMAX —
MAX5021EPA 50% -40°C to +85°C 8 PDIP —
MAX5022EUT 75% -40°C to +85°C 6 SOT23-6 AASR
MAX5022EUA 75% -40°C to +85°C 8 µMAX —
MAX5022EPA 75% -40°C to +85°C 8 PDIP —
DUTY
CYCLE
TEMP.
RANGE
PIN PACKAGE
TOP
MARK
TOP VIEW
16OPTO
CS
GND
NDRV
MAX5021
2
MAX5022
34
SOT23
1
OPTO
2
5 V
IN
IN
V
CC
V
CC
3
4
PDIP/µMAX
MAX5021
MAX5022
87CS
6
5
GNDV
NDRV
N.C.N.C.
MAX5021/MAX5022
Current-Mode PWM Controllers for Isolated
Power Supplies
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN= +11V to +28V, VCS= 0, OPTO is unconnected, 10nF bypass capacitors at VINand VCC, NDRV unconnected, TA= -40°C to
+85°C, unless otherwise noted. Typical values are at V
IN
= +12V, TA= +25°C, unless otherwise noted.) (Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VINto GND .............................................................-0.3V to +30V
V
CC
to GND............................................................-0.3V to +13V
NDRV to GND.............................................-0.3V to (V
CC
+ 0.3V)
CS, OPTO to GND ....................................................-0.3V to +6V
NDRV Short-Circuit to GND........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SOT23 (derate 8.7mW/°C above +70°C).............696mW
8-Pin µMAX (derate 4.5mW/°C above +70°C) ..............362mW
8-Pin PDIP (derate 9.1mW/°C above +70°C)................727mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-55°C to +150°C
Lead Temperature (soldering 10s) ..................................+300°C
)
)
)
UNDERVOLTAGE LOCKOUT/STARTUP
CURRENT-LIMIT COMPARATOR
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Undervoltage Lockout Wakeup
Level
Undervoltage Lockout Shutdown
Level
VIN Supply Current at Startup I
VIN Range V
Undervoltage Lockout
Propagation Delay
INTERNAL SUPPLY
VCC Regulator Set Point V
VIN Supply Current after Startup I
GATE DRIVER
Driver Output Impedance
Driver Peak Sink Current I
Driver Peak Source Current I
PWM COMPARATOR
Comparator Offset Voltage VO
CS Input Bias Current I
Propagation Delay from
Comparator Input to NDRV
Minimum On-Time T
Current-Limit Trip Threshold V
Current-Limit Propagation Delay
from Comparator Input to NDRV
V
V
STARTVIN
T
T
R
ON(LOW
R
ON(HIGH
SOURCE
T
ON(MIN
UVR
UVF
UVR
UVF
CCSP
SINK
PWM
T
VIN rising 22 24 26 V
VIN falling 9.3 10 10.9 V
IN
VIN steps up from +9V to +26V 5
VIN steps down from +26V to +9V 1
VIN = +11V to +28V, sourcing 1µA to 5mA
from V
VIN = +28V, OPTO connected to GND 0.9 2.43
IN
VIN = +28V, OPTO unconnected (Note 2) 0.4
Measured at NDRV sinking 5mA 10 20
Measured at NDRV sourcing 5mA 20 40
PWMVOPTO
CS
25mV overdrive 60 ns
CS
25mV overdrive 60 ns
CL
= +22V 50 85 µA
CC
- V
CS
11 28 V
7.0 10.5 V
250 mA
150 mA
600 750 900 mV
-2 +2 µA
150 ns
540 600 660 mV
µs
mA
Ω
MAX5021/MAX5022
Current-Mode PWM Controllers for Isolated
Power Supplies
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VIN= +11V to +28V, VCS= 0, OPTO is unconnected, 10nF bypass capacitors at VINand VCC, NDRV unconnected, TA= -40°C to
+85°C, unless otherwise noted. Typical values are at V
IN
= +12V, TA= +25°C, unless otherwise noted.) (Note 1)
Note 1: All devices are 100% tested at T
A
= +25°C. All limits over temperature are guaranteed by characterization.
Note 2: This minimum current after startup is a safeguard that prevents the V
IN
pin voltage from rising in the event
that OPTO and NDRV become unconnected.
Typical Operating Characteristics
(VIN= 15V, TA = +25°C, unless otherwise noted.)
23.9
24.0
24.1
24.2
24.3
UNDERVOLTAGE LOCKOUT
vs. TEMPERATURE
MAX5021/22 toc01
TEMPERATURE (°C)
UNDERVOLTAGE LOCKOUT (V)
-40 20 40-20 0 60 80
VIN RISING
9.8
9.9
10.0
10.1
10.2
UNDERVOLTAGE LOCKOUT
vs. TEMPERATURE
MAX5021/22 toc02
TEMPERATURE (°C)
UNDERVOLTAGE LOCKOUT (V)
-40 20 40-20 0 60 80
VIN FALLING
47
48
49
50
51
52
53
-40 -20 0 20 40 60 80
STARTUP CURRENT
vs. TEMPERATURE
MAX5021/22 toc03
TEMPERATURE (°C)
STARTUP CURRENT (µA)
VIN = 23.0V
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
OSCILLATOR
Switching Frequency f
Maximum Duty Cycle D
SW
MAX
MAX5021 50 51
MAX5022 75 76
OPTO INPUT
OPTO Pullup Voltage V
OPTO Pullup Resistance R
OPTO
OPTO
OPTO sourcing 10µA 5.5 V
230 262 290 kHz
4.5 6.2 7.9 kΩ
%
MAX5021/MAX5022
Current-Mode PWM Controllers for Isolated
Power Supplies
4 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VIN= 15V, TA = +25°C, unless otherwise noted.)
1.40
1.45
1.50
1.55
1.60
SUPPLY CURRENT
vs. TEMPERATURE
MAX5021/22 toc04
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
-40 20 40-20 0 60 80
VIN = 28.0V
V
OPTO
= VCS = 0
9.00
9.03
9.09
9.06
9.12
9.15
-40 0-20 20 40 60 80
MAXIMUM VCC
vs. TEMPERATURE
MAX5021/22 toc05
TEMPERATURE (°C)
MAXIMUM V
CC
(V)
VIN = 28.0V
V
CS
= 0
OPTO = UNCONNECTED
7.70
7.90
7.80
8.10
8.00
8.20
8.30
-40 20 40-20 0 60 80
MINIMUM VCC
vs. TEMPERATURE
MAX5021/22 toc06
TEMPERATURE (°C)
MINIMUM V
CC
(V)
VIN = 10.8V
5mA LOAD ON V
CC
VCS = 0
OPTO = UNCONNECTED
570
590
580
610
600
630
620
640
-40 0 20-20 40 60 80
CURRENT SENSE THRESHOLD
vs. TEMPERATURE
MAX5021/22 toc07
TEMPERATURE (°C)
CURRENT SENSE THRESHOLD (mV)
+3σ
-3σ
MEAN
TOTAL NUMBER OF
DEVICES = 50
0
5
15
10
20
25
540 580560 620
640 660
CURRENT SENSE
THRESHOLD
MAX5021/22 toc08
CURRENT SENSE THRESHOLD (mV)
FREQUENCY (%)
TOTAL NUMBER
OF DEVICES = 200
600
245
255
250
265
260
275
270
280
-40 0 20-20 40 60 80
OSCILLATOR FREQUENCY
vs. TEMPERATURE
MAX5021/22 toc09
TEMPERATURE (°C)
OSCILLATOR FREQUENCY (kHz)
TOTAL NUMBER
OF DEVICES = 50
+3σ
-3σ
MEAN
0
5
15
10
20
25
230 250240 260 270 280 290
OSCILLATOR FREQUENCY
MAX5021/22 toc10
OSCILLATOR FREQUENCY (kHz)
FREQUENCY (%)
TOTAL NUMBER
OF DEVICES = 200
50
55
65
60
70
75
-40 0-20 20 40 60 80
CURRENT SENSE DELAY
vs. TEMPERATURE
MAX5021/22 toc11
TEMPERATURE (°C)
CURRENT SENSE DELAY (ns)
0
2
1
4
3
5
6
-40 20 40-20 0 60 80
UNDERVOLTAGE LOCKOUT
DELAY vs. TEMPERATURE
MAX5021/22 toc12
TEMPERATURE (°C)
UNDERVOLTAGE LOCKOUT DELAY (µs)
VIN RISING
VIN FALLING
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