Power Management IPS20 and IPS21

© Copyright 2006-2009 - ASIC Advantage, Inc.

AADS00001/AA743

- Revision 5– Dec 2008

11 / 12

VSENSE (Pin 2), VCOMP (Pin 3)

The internal voltage reference for voltage feedback is 1.19 volts. The output voltage being sensed/regulated should

have a voltage divider to 1.19 volts connected to pin 2. For good voltage feedback loop performance, no capacitor

should be connected from pin 2 to ground. The recommended series-RC component values from pin 2 to pin 3 to

roll-off the loop gain are 10k ohms and 68nF.

OPTO (Pin 4)

The OPTO pin is a current source (unlike a shunt regulator like the TL431, which is a current sink). The intended

connection for the voltage feedback network is to connect the OPTO pin to the anode of the photodiode in an

optoisolator, with the cathode of the photodiode connected to ground. The IPS20/21 use very little current to operate,

but the user is reminded that the OPTO current being sourced comes through the VCC pin.

ICOMP (Pin 5) and IS (Pin 6)

The current sense resistor connects between IS and GND. For a positive output power supply, IS is the negative

output pin. The internal voltage reference for current limiting (50 millivolts for IPS20, 100 millivolts for IPS21) is

referenced to GND. The recommended component values from pin 5 to pin 6 to roll-off the loop gain are a series 10k

ohms and 220pF, in parallel with 68nF. To reduce susceptability to noise spikes, an additional RC filter network

might be desireable from IS to GND (refer to the Typical Application Schematic Figure 1 above).

OUT(-) (Pin 7)

The negative side of the internal voltage reference for voltage feedback is connected here. For a typical application

with a positive output voltage and a current sense resistor, this pin connects to the more-negative pin of the output

voltage. This configuration allows the voltage feedback to compensate for the voltage drop across the current sense

resistor (which will vary with load).

EVALUATION BOARD

There is an evaluation board (AAEV2021) available for the IPS20 and IPS21 feedback controllers. Contact AAI

Marketing for more details. There are also benchmark/reference designs available that include AAI Flyback

Controllers, and Application Notes.

PACKAGE DIMENSIONS AND MARKING

The IPS20 and IPS21 are available in plastic 8-pin DIP and plastic 8-pin SOIC packages. Refer to the latest version

of specification AAPS001 (ASIC Advantage’s “Package Numbering, Marking, and Outline Standard”, available at

www.asicadvantage.com) for specific information concerning the package dimensions and package marking.

Part Number/Tube

Part Number/Tape&Reel

Package

Temperature Range

IPS20C-D-G-LF

IPS21C-D-G-LF

NA

8-Pin PDIP

0

°C to +70°C

Commercial

IPS20I-D-G-LF

IPS21I-D-G-LF

NA

8-Pin PDIP

-40

°C to +85°C

Industrial

IPS20C-SO-G-LF

IPS21C-SO-G-LF

IPS20C-SO-G-LF-TR

IPS21C-SO-G-LF-TR

8-Pin SOIC

0

°C to +70°C

Commercial

IPS20I-SO-G-LF

IPC21I-SO-G-LF

IPS20I-SO-G-LF-TR

IPC21I-SO-G-LF-TR

8-Pin SOIC

-40

°C to +85°C

Industrial