MAX5019 Datasheet, PDF (1/14 Pages) Maxim Integrated Products – Current-Mode PWM Controllers with Integrated Startup Circuit

19-2115; Rev 0; 7/01
Current-Mode PWM Controllers with Integrated
Startup Circuit
General Description
The MAX5019/MAX5020 integrate all the building
blocks necessary for implementing DC-DC fixed-fre-
quency power supplies. Either primary- or secondary-
side regulation may be used to implement isolated or
nonisolated power supplies. These devices are current-
mode controllers with an integrated high-voltage start-
up circuit suitable for telecom/industrial voltage range
power supplies. Current-mode control with leading-
edge blanking simplifies control-loop design and inter-
nal ramp compensation circuitry stabilizes the current
loop when operating at duty cycles above 50%
(MAX5019). The MAX5019 allows 85% operating duty
cycle and can be used to implement flyback converters
whereas the MAX5020 limits the operating duty cycle to
less than 50% and can be used in single-ended for-
ward converters. A high-voltage startup circuit allows
these devices to draw power directly from the 18V to
110V input supply during startup. The switching fre-
quency is internally trimmed to 275kHz ±10%, thus
reducing magnetics and filter component costs.
The MAX5019/MAX5020 are available in 8-pin SO
packages.
Warning: The MAX5019/MAX5020 operate with high
voltages. Exercise caution.
Applications
Telecom Power Supplies
Industrial Power Supplies
Networking Power Supplies
Isolated Power Supplies
Features
o Wide Input Range: (18V to 110V) or (13V to 36V)
o Isolated (without optocoupler) or Nonisolated
Power Supply
o Current-Mode Control
o Leading-Edge Blanking
o Internally Trimmed 275kHz ±10% Oscillator
o Low External Component Count
o Soft-Start
o High-Voltage Startup Circuit
o Pulse-by-Pulse Current Limiting
o Thermal Shutdown
o SO-8 Package
Ordering Information
PART
TEMP. RANGE
MAX5019CSA*
0°C to +70°C
MAX5019ESA*
-40°C to +85°C
MAX5020CSA*
0°C to +70°C
MAX5020ESA*
-40°C to +85°C
*See Selector Guide at end of data sheet.
PIN-PACKAGE
8-SO
8-SO
8-SO
8-SO
Typical Operating Circuit
Pin Configuration
V_IN
V_OUT
TOP VIEW
V_DD
V+
V+ 1
V_DD 2
FB 3
SS_SHDN 4
MAX5019/
MAX5020
8 V_CC
7 NDRV
6 GND
5 CS
8-SO
MAX5020
NDRV
V_CC
CS
SS_SHDN
GND
FB
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