IPS21C-D-G-LF_技术文档

Power Management IPS20 and IPS21

IN-PLUG^®series: IPS20 and IPS21

Precision Feedback Controllers

Fixed and PTAT references

REV5

INTRODUCTION

DESCRIPTION

FEATURES

•

Dual precision regulators for SMPS voltage and

current control

IN-PLUG^®IPS20 & IPS21 Integrated Circuits are

low-voltage current sensing feedback controllers used

in Switch Mode Power Supplies to control load-side

current and voltage. They have been designed to limit

the power dissipated in the sensing circuitry for high

output current applications that require current

limiting. They also provide excellent loop stability

and superb transient response. They both incorporate a

4V shunt regulator for maximum flexibility to power

the chip.

•

Output currents up to 50A

Output voltage down to 1.2V

54mV or 100mV current sensing voltage

1.19V voltage reference

Operates with grounded optocoupler

4V shunt regulator for VCC supply

APPLICATIONS

•

Fast chargers for power tools and other

applications

The IPS20 and IPS21 only differ by the characteristics

of the current sensing references.

•

Battery eliminators

Industrial and bench-type power supplies

Distributed power systems

The IPS20 incorporates a trimmed 54mV reference

with a positive temperature coefficient which closely

matches that of a PCB copper trace. This copper trace

sensing method can be used inexpensively with very

low associated power losses.

PIN CONFIGURATION: DIP-8 / SOIC-8

The IPS21 incorporates a temperature compensated

100mV reference for more conventional resistors.

Both controllers feature the same voltage regulator

section with a trimmed temperature stable voltage

reference of 1.19V. This allows the output voltage of

the SMPS to be set to any value down to about 1.2V.

VCC

VS

1

8

GND

OUT (-)

IS

IPS20

IPS21

VCOMP

OPTO

ICOMP

4

5

The IPS20 and IPS21 are suitable for any SMPS and

any make of SMPS controllers, including flyback,

forward, PFC and DC/DC solutions.

These flyback controllers work best in complement

with the IN-PLUG^®family of IPS1x flyback

controllers, IPS10x PFC controllers and IPS20x Push-

Pull controllers.

ORDERING INFORMATION

For part number, packaging, and ordering

information, please refer to the second-to-last page of

this datasheet.

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Power Management IPS20 and IPS21

FUNCTIONAL BLOCK DIAGRAM

4V Shunt Regulator

8

1

GND

VCC

Trimmed

Current Sensing

50mV PTAT

100mV Temp.Stable

Trimmed 1.25V

Temp. Stable

Bandgap Regulator

7

6

OUT (-)

IS

2

VS

VOLTAGE

ERROR

AMPLIFIER

CURRENT

ERROR

AMPLIFIER

3

OPTOCOUPLER

CURRENT-SOURCE

CONTROL

5

VCOMP

ICOMP

4

OPTO

IPS20 / IPS21

PIN DESCRIPTION

Description

IC positive supply pin.

1- VCC

The chip behaves like a 4 volt zener diode referenced to GND

Voltage sensing pin.

2- VS

This is the inverting input of the voltage error amplifier. The positive input of the amplifier is connected

to an internal trimmed 1.20V voltage reference. An external voltage divider connected to this point sets

the output voltage. This pin is also used for voltage loop compensation when required.

Voltage loop compensation pin.

3- VCOMP

This is the output of the voltage error amplifier. The voltage loop compensation network, when required,

is connected between this point and VS pin. Please note that this pin is not a zero-impedance node (1KΩ

nominal).

Optocoupler driver pin.

4- OPTO

This pin drives and external optocoupler connected to GND. A current-mode drive is used for maximum

noise rejection.

Current loop compensation pin. (similar to VCOMP)

5- ICOMP

This is the output of the current error amplifier. The current loop compensation network, when required,

is connected between this point and the IS pin. Please note that this is not a zero-impedance point (1KΩ

nominal).

Current sensing pin.

6- IS

This pin is the inverting input of the current sense amplifier. The positive input of the amplifier is

connected to an internal trimmed reference. The sensing threshold is 50mV PTAT (IPS20) or 100mV

constant (IPS21). This pin should be connected through a resistor to the external current sensing resistor.

Negative output pin.

7- OUT (-)

8- GND

This pin is the negative side of the 1.20V trimmed voltage reference. It should be connected to the

negative output of the SMPS.

Ground pin.

This is the most negative IC pin. The first output decoupling capacitor should return to it. Do not confuse

this pin with the IS pin and the OUT(-) pin which are described above.

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Power Management IPS20 and IPS21

TYPICAL FEEDBACK CIRCUITRY WITH CONTROL OF PRIMARY FLYBACK CONVERTER

L1

D1

IN+

DC or Rectified AC

IN+

OUT+

SCHOTTKY

+

OUTPUT

C5

R3

RV1

RV2

C6

TX1

FLYBACK

U1

CONVERTER

1

2

3

4

8

7

6

5

VCC

VSENSE OUT(-)

VCOMP IS

GND

OUT-

OPTO ICOMP

C1

R1

C3

C4

IPS20/21

C2

R2

R4

U2

RISENSE

SecondaryGND

OPTOCOUPLER

Fig. 1

1) Current limiting:

The current limiting is adjustable through RISENSE

2) Regulated Voltage:

The regulated voltage is adjustable through RV1 and RV2

3) Compensation

The voltage-control trans-conductance operational amplifier can be fully compensated. Both of its compensation

pins are directly accessible for external compensation components.

The suitable compensation network is shown in Fig.1. It consists of a capacitor C1 and a resistor R1in series,

connected in parallel with another capacitor C2.

The current-control trans-conductance operational amplifier can be fully compensated. Both of its compensation

pins are directly accessible for external compensation components.

The suitable compensation network is shown in Fig.1. It consists of a resistor R2 and a capacitor

C2 in series, in parallel with a capacitor C3. Resistor R4 provides the input impedance that the compensation

network works with. Capacitor C4, with R4, implements a small amount of filtering.

Determination of V_out(Output Voltage):

V_out= VSENSE x (RV1+RV2)/ RV2

(Nominal VSENSE = 1.19V)

Determination of I_limit(Current Limit):

I_limit= IS threshold / RISENSE

Nominal IS threshold :

IPS20= 54mV

IPS21= 100mV

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Power Management IPS20 and IPS21

IN-PLUG^®IPS20 and IPS21

FUNCTIONAL DESCRIPTION

IPS20 and IPS21 are highly integrated feedback solutions for Switch Mode Power Supplies applications requiring

constant voltage and constant current mode. They were especially designed to reduce the power dissipated in the

load-side current sensing resistor of power supplies with high output current They provide precise voltage and

current regulation that can be fully and independently adjusted. They source the current necessary to drive a ground-

referred optocoupler connected to the line side controller.

They both incorporate the same trimmed temperature compensated 1.2V reference to set the output voltage. They

only differ by the characteristics of the current sensing references. The IPS20 features a trimmed 50mV reference

with a positive temperature coefficient which closely matches that of a PCB copper trace. This copper trace sensing

method can be used inexpensively with very low associated power losses. The IPS21 incorporates a constant 100mV

reference for more conventional resistors.

Both the output voltage and current sense can be independently adjusted through respectively RV1/RV2 and

RISENSE (FIG.1) This information is presented to the IPS20/21 controller, which drives the optocoupler through the

OPTO current-mode output pin.

The shunt regulator operates like a zener diode, keeping the chip supply voltage at about 4 volts. At start-up, when

the 4 volts are reached, the controller starts normal operation. The overall chip consumption in this case is about 600

μA.

If the IPS20 or IPS21 Vcc is connected to the converter output voltage, then under start-up or short-circuit

conditions, the IPS20/21 isn’t supplied with a high enough voltage. This is due to the fact that the chip has its power

supply line in common with the power supply line of the system. Therefore, the current limitation can only be

ensured by the primary PWM module, that should be chosen accordingly.

If the primary current limitation is considered not to be precise enough for the application, then a sufficient supply

for the IPS20/21 has to be ensured under any condition. It would then be necessary to add some circuitry to supply

the chip with a separate power line.

FIG.2 OUTPUT VOLTAGE VERSUS OUTPUT CURRENT

The schematic in Figure 3 below shows how to realize a low-cost power supply for the IPS20/21 (with no additional

winding). Please pay attention to the fact that in the particular case presented here, this low-cost power supply can

reach voltages as high as twice the voltage of the regulated line.

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Power Management IPS20 and IPS21

AUXILLIARY POWER SUPPLY

This simple circuitry allows to supply the chip with a separate power line. In case of short-circuit, when Vout+ <

Vcc, the chip still keeps working properly and limits the output current to its maximum targeted value.

VOUT+

D2

Auxilliary Power Supply

TR1

DIODE

+ C2

R1

C3

U1

VCC

VSENSE OUT(-)

VCOMP IS

D1

1

2

3

4

8

7

6

5

GND

SCHOTTKY

OPTO ICOMP

IPS20/21

+ C1

R2

VOUT-

DERIVATIVE OF AAI’s PATENTED SNUBBER NETWORK

This technique powers the feedback controller under all circumstances including short-circuits and is especially

suitable for flyback, PFC and forward converters.

D1

VOUT+

snubber network

TR1

SCHOTTKY

C1

R1

+

D2

C3

U1

+

1

2

3

4

8

7

6

5

VCC

VSENSE OUT(-)

VCOMP IS

GND

C4

D3

OPTO ICOMP

+

IPS20/21

C2

R2

VOUT-

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Power Management IPS20 and IPS21

ELECTRICAL CHARACTERISTICS

ABSOLUTE MAXIMUM RATING

Characteristics

Value

140

UNITS

mA

IPS 20 and IPS21 Max I_CC(4V shunt regulator)

Opto sourcing current with external resistor

Operating junction temperature

20

mA

- 40 to 150

- 55 to 150

260

°C

Storage temperature range

Lead temperature (3 mm from case for 5 sec.)

PARAMETER

Supply, Bias

TEST CONDITIONS

PARAMETERS

UNITS

MIN.

3.8

TYP.

4

MAX.

4.2

Shunt regulator voltage

Shunt regulator dynamic

resistance (see figure 1)

Shunt regulator max peak

repetitive current

ICC = 1 to 30 mA

1 to 50 mA

V

Ω

-

1

3

-

100

-

mA

μΑ

Min I_CCto ensure operation

(internal current)

600

Voltage Regulation

I

_OPTO= 500 μA

Zin=10KΩ

VSENSE threshold (note1)

1.17

-

1.19

+/- 3

1.21

+/- 6

V

VSENSE threshold variation with

temperature

I_OPTO= 500 μA, -40°C to +85°C

mV

(see figure 2)

Output impedance of VCOMP

Voltage gain to VCOMP

Unity gain bandwidth

-

1

-

KΩ

dB

(see figure 7)

115

500

82

-

KHz

Phase margin in unity gain

VSENSE Input current

-

Degrees

μA

1.0

Transconductance from VSENSE

to OPTO

@ V_CC= 2.5V

(see figure 5)

@ V_CC= 5V

-

4

-

mA/mV

mA

Max OPTO output sourcing

current without ext. resistor

1.2

10

(see figure 5)

@ V_CC= 2.5V

(see figure 3)

Max OPTO output sourcing

current with ext. resistor

-

mA

Current Limiting

I_CC= 1 mA

ISENSE threshold (IPS20)

52

-

54

0.16

99

56

-

mV

mV /°C

mV

(see figure 3)

ISENSE threshold variation with

temperature (IPS20)

I_CC= 1 mA, -40°C to +85°C

(see figure 3)

I_CC= 1 mA

ISENSE threshold (IPS21)

97

-

101

-

(see figure 4)

ISENSE threshold variation with

temperature (IPS21)

I_CC= 1 mA, -40°C to +85°C

(see figure 4)

3

μV/°C

Output impedance of ICOMP

Voltage gain to ICOMP

-

1

-

ΚΩ

(see figure 8)

138

dB

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Power Management IPS20 and IPS21

Unity gain bandwidth to ICOMP

Phase margin in unity gain

ISENSE Input current

(see figure 8)

-

2

-

MHz

Degrees

uA

54

-1.0

Transconductance from ISENSE

to OPTO

(see figure 6a & 6b)

IPS20: 6a, IPS21: 6b

-

60

-

mA/mV

Max OPTO output sourcing

current without ext. resistor

@ V_CC= 1.30V

(see figure 5)

@ V_CC= 2.5V

(see figure 5)

1.2

10

-

mA

Max OPTO output sourcing

current with ext. resistor

Note1: Tighter tolerances to 0.5% available upon request.

Note2: All values are @ 25°C unless otherwise specified.

Note3: Electrical parameters, although guaranteed, are not all 100% tested in production.

Figure 1: IPS20 and IPS21 4V Shunt Regulator Icc

300

250

200

150

100

50

0

1

2

3

4

5

6

Shunt Voltage (V)

Figure 2: IPS20 & IPS21 Trimmed 1.20V Reference

1.2

1.195

1.19

1.185

1.18

1.175

1.17

-40

-20

0

20

40

60

80

100

120

Temp (°C)

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Power Management IPS20 and IPS21

Figure 3: IPS20 Ref. with copper temperature drift compensation

70

65

60

55

50

45

40

-40

-20

0

20

40

60

80

100

Temperature (°C)

Figure 4: IPS21 100mV Reference

100

99.5

99

98.5

98

97.5

97

-50

-30

-10

10

30

50

70

90

110

130

Temperature (°C)

Figure 5: Transfer function of the voltage regulation

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

1.185

1.186

1.187

1.188

1.189

1.19

Vsense (V)

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Power Management IPS20 and IPS21

Figure 6a: Transfer Function of the IPS20 Current Regulation

2.2

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

-0.2

47.5

48

48.5

49

49.5

50

50.5

51

ISENSE (mV)

Figure 6b: Transfer function of the IPS21 current regulation

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

98.5 98.6 98.7 98.8 98.9 99 99.1 99.2 99.3 99.4 99.5

Isense (mV)

Fig 7: Open loop gain of VSENSE amplifier without compensation

140

120

100

80

60

40

20

0

-20

0.001

0.01

0.1

1

10

100

1000

10000

100000

1000000

Frequency (Hz)

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Power Management IPS20 and IPS21

Fig 8: Open loop gain of Isense amplifier without compensation

160

140

120

100

80

60

40

20

0

-20

-40

0.001

0.01

0.1

1

10

100

1000

10000

100000

1000000

10000000

Frequency (Hz)

APPLICATION INFORMATION

The IPS20 and IPS21 chips are intended for use as voltage feedback control and current limiting on the secondary

side of switching power supplies.

Powering the chip (Pin 1 - VCC and Pin 8 - GND)

The VCC pin acts like a 4 volt zener. This is a different chip-power concept than the IPS25, a self-powered feedback

controller, optimized for output currents below 1A (see IPS25 datasheet for details). The GND pin is the lowest

voltage the chip sees. What this means is that in a typical “positive output voltage with current sense resistor”

application, the GND pin DOES NOT go to the negative output pin of the power supply, rather it goes to the

“transformer side” of the current-sense resistor. No input voltage should be greater than VCC or less than GND. It is

recommended as good engineering practice to have a decoupling capacitor from VCC-to GND of 10uF. The intended

design implementation for powering the chip is to have a resistor from VCC to either the output voltage or a separate

supply.This resistor should be sized such that at minimum supply voltage (and subtracting 4 volts for the VCC

voltage), there is enough current to operate the chip (3mA) plus supply the optoisolator.

Tips for lab experiments

The IPS20/21 are fabricated in a low-voltage IC process (lower than the IPS25). This means that they can be

damaged with pin voltages greater than 7 volts. When testing designs using an IPS20/21, it is typical to perform

debug with a laboratory current-limited external power supply attached to the VCC pin. This external supply should

be set for around 5 volts and 10 milliamps. It is possible to damage an IPS20/21 if one of these lab supplies is set for

(say) 12 volts and 10 milliamps, the lab supply is powered-on, and then the lab supply is connected to the IPS20/21,

because the VCC voltage will be 12 volts (in this example) until the IPS20/21 starts conducting current and

discharges any output capacitance in the lab supply.

Note that the overcurrent performance of a power supply using an IPS20/21 will be different based on whether the

chip is powered by the output (where the VCC supply will be collapsing) versus from an independent supply. The

user should be sure to check that the output voltage and current characteristics during overcurrent conditions meet

his/her specific needs. During startup and short-circuit conditions, the IPS20/21 may not have enough supply voltage

to operate. In this situation, the output current limitation must come from the primary side PWM module, and must

be designed accordingly.

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Power Management IPS20 and IPS21

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/Tape&Reel

Part Number/Tube

Package

Temperature Range

IPS20C-D-G-LF

IPS21C-D-G-LF

NA

8-Pin PDIP

Commercial

0°C to +70°C

-40°C to +85°C

0°C to +70°C

-40°C to +85°C

IPS20I-D-G-LF

IPS21I-D-G-LF

NA

8-Pin PDIP

8-Pin SOIC

Industrial

Commercial

Industrial

IPS20C-SO-G-LF-TR

IPS21C-SO-G-LF-TR

IPS20C-SO-G-LF

IPS21C-SO-G-LF

IPS20I-SO-G-LF-TR

IPC21I-SO-G-LF-TR

IPS20I-SO-G-LF

IPC21I-SO-G-LF

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Power Management IPS20 and IPS21

The following is a brief overview of certain terms and conditions of sale of product. For a full and complete copy of

all the General Terms and Conditions of Sale, visit our webpage http://www.asicadvantage.com/terms.htm.

LIMITED WARRANTY

The product is warranted that it will conform to the applicable specifications and be free of defects for one year.

Buyer is responsible for selection of, use of and results obtained from use of the product. Buyer indemnifies and

holds ASIC Advantage, Inc. harmless for claims arising out of the application of ASIC Advantage, Inc.’s products to

Buyer’s designs. Applications described herein or in any catalogs, advertisements or other documents are for

illustrative purposes only.

CRITICAL APPLICATIONS

Products are not authorized for use in critical applications including aerospace and life support applications. Use of

products in these applications is fully at the risk of the Buyer. Critical applications include any system or device

whose failure to perform can result in significant injury to the user.

LETHAL VOLTAGES

Lethal voltages could be present in the applications. Please comply with all applicable safety regulations.

INTELLECTUAL PROPERTY RIGHTS AND PROPRIETARY DATA

ASIC Advantage, Inc. retains all intellectual property rights in the products. Sale of products does not confer on

Buyer any license to the intellectual property. ASIC Advantage, Inc. reserves the right to make changes without

notice to the products at any time. Buyer agrees not to use or disclose ASIC Advantage Inc.’s proprietary

information without written consent.

TRADEMARKS AND PATENTS

- IN-PLUG® is a registered trademark of ASIC Advantage, Inc.

- AAI’s modified snubber network is patented under the US Patent # 6,233,165. IN-PLUG® Customers are granted

a royalty-free licence for its utilization, provision the parts are purchased factory direct or from an authorized agent.

PROTECTION FOR CUSTOM IN-PLUG® SOLUTIONS

When AAI accepts to design and manufacture IN-PLUG® products to Buyer’s designs or specifications, buyer has

certain obligations to provide defense in a suit or proceeding claiming infringement of a patent, copyright or

trademark or for misappropriation of use of any trade secrets or for unfair competition.

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Buyer agrees that at all times it will comply with all applicable federal, state, municipal, and local laws, orders and

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TITLE AND DELIVERY

All shipments of goods shall be delivered ExWorks, Sunnyvale, CA, U.S.A. Title in the goods shall not pass to Buyer

until ASIC Advantage, Inc. has received in full all amounts owed by Buyer.

LATEST DATASHEET UPDATES

For the latest datasheet updates, visit our web page: http://www.in-plug.com/datasheets.htm.

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ASIC Advantage INC.

1290-B Reamwood Ave, Sunnyvale California 94089, USA

Tel: (1) 408-541-8686 Fax: (1) 408-541-8675

Websites: http://www.in-plug.com - http://www.asicadvantage.com

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12 / 12


型号：	IPS21C-D-G-LF
厂家：	ETC
描述：	Precision Feedback Controllers Fixed and PTAT references 精密反馈控制器固定和PTAT引用控制器
文件：	总12页 (文件大小：94K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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