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Power Supply Supervisory Circuit

Includes Over-voltage,

Under-voltage, And Current

Sensing Circuits

Internal 1% Accurate

Reference

Programmable Time Delays

SCR “Crowbar” Drive Of

300mA

Remote Activation Capability

Optional Over-voltage Latch

Uncommitted Comparator

Inputs For Low Voltage

Sensing (UC1544 Series

Only)

The monolithic integrated circuits contain all the functions necessary to monitor

and control the output of a sophisticated power supply system. Over-voltage (O.V.)

sensing with provision to trigger an external SCR “crowbar” shutdown; an under-

voltage (U.V.) circuit which can be used to monitor either the output or to sample

the input line voltage; and a third op amp/comparator usable for current sensing

(C.L.) are all included in this IC, together with an independent, accurate reference

generator.

Both over- and under-voltage sensing circuits can be externally programmed for

minimum time duration of fault before triggering. All functions contain open collec-

tor outputs which can be used independently or wire-or’ed together, and although

the SCR trigger is directly connected only to the over-voltage sensing circuit, it

may be optionally activated by any of the other outputs, or from an external signal.

The O.V. circuit also includes an optional latch and external reset capability.

The UC1544/2544/3544 devices have the added versatility of completely uncom-

mitted inputs to the voltage sensing comparators so that levels less than 2.5V may

be monitored by dividing down the internal reference voltage. The current sense

circuit may be used with external compensation as a linear amplifier or as a high-

gain comparator. Although nominally set for zero input offset, a fixed threshold may

be added with an external resistor. Instead of current limiting, this circuit may also

be used as an additional voltage monitor.

The reference generator circuit is internally trimmed to eliminate the need for ex-

ternal potentiometers and the entire circuit may be powered directly from either the

output being monitored or from a separate bias voltage.

BLOCK DIAGRAM

Note:  For each terminal, first number refers to 1543 series, second to 1544 series.

* On 1543 series, this function is internally connected to V

REF.

UC1543 UC1544

UC2543 UC2544

UC3543 UC3544

DESCRIPTION

FEATURES

4/97

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ABSOLUTE MAXIMUM RATINGS

Input Supply Voltage, V

IN

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V

Sense Inputs, Voltage Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  0 to V

IN

SCR Trigger Current (Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  -600mA

Indicator Output Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V

Indicator Output Sink Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50mA

Power Dissipation (Package Limitation). . . . . . . . . . . . . . . . . . . . . . . 1000mW

Operating Temperature Range

  UC1543, UC1544 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55°C to +125°C

  UC2543, UC2544 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25°C to +85°C

  UC3543, UC3544 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  0°C to +70°C

Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . -65°C to +150°C

Note 1: At higher input voltages, a dissipation limiting resistor, RG, is required.

Note 2: Currents are positive-into, negative-out of the specified terminal. Con-

sult Packaging section of Databook for thermal limitations and considerations

of package.

UC1543 UC1544

UC2543 UC2544

UC3543 UC3544

CONNECTION DIAGRAMS

DIL-16, SOIC-16 (TOP VIEW)

J or N, DW Package

UC 1543

UC 2543

UC 3543

DIL-18, SOIC-18 (TOP VIEW)

J or N, DW Package

UC 1544

UC 2544

UC 3544

PACKAGE PIN FUNCTION

FUNCTION

PIN

N/C

1

SCR Trigger

2

Remote Activate

3

Reset

4

O.V. Indicate

5

N/C

6

O.V. Delay

7

O.V. Input

8

N/C

9

N/C

10

U.V. Input

11

U.V. Delay

12

U.V. Indicate

13

C.L. INV. Input

14

C.L. N.I. Input

15

Offset/Comp

16

C.L. Output

17

Ground

18

V

REF

19

V

IN

20

PLCC-20, LCC-20

(TOP VIEW)

Q or L Package

PACKAGE PIN FUNCTION

FUNCTION

PIN

N/C

1

SCR Trigger

2

Remote Activate

3

Reset

4

O.V. Indicate

5

N/C

6

O.V. Delay

7

O.V. N.I. Input

8

O.V. INV. Input

9

U.V. N.I. Input

10

U.V. INV. Input

11

U.V. Delay

12

U.V. Indicate

13

C.L. INV. Input

14

C.L. N.I. Input

15

Offset/Comp

16

C.L. Output

17

Ground

18

V

REF

19

V

IN

20

PLCC-20, LCC-20

(TOP VIEW)

Q or L Package

2

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PARAMETER

TEST CONDITIONS

UC1543/UC1544

UC2543/UC2544

UC3543/UC3544

UNITS

MIN

TYP

MAX

MIN

TYP

MAX

Input Voltage Range

T

= 25°C to T

MAX

4.5

40

4.5

40

V

T

MIN

 to T

MAX

4.7

40

4.7

40

V

Supply Current

V

IN

 = 40V, Output Open, T

= 25°C

7

10

7

10

mA

T

MIN

 

 T

J

 

 T

MAX

15

15

mA

Reference Section

Output Voltage

T

J

 = 25°C

2.48

2.50

2.52

2.45

2.50

2.55

V

Output Voltage

Over Temperature Range

2.45

2.55

2.40

2.60

V

Line Regulation

V

IN

 = 5 to 30V

1

5

1

5

mV

Load Regulation

I

REF

 = 0 to 10mA

1

10

1

10

mV

Short Circuit Current

V

REF

 = 0

-10

-20

-40

-12

-20

-40

mA

Temperature Stability

50

50

ppm

/°C

SCR Trigger Section

Peak Output Current

V

IN

 = 5V, R

G

 = 0, V

O

 = 0

-100

-300

-600

-100

-300

-600

mA

Peak Output Voltage

V

IN

 = 15V, I

= -100mA

12

13

12

13

V

Output Off Voltage

V

IN

 = 40V

0

0.1

0

0.1

V

Remote Activate Current

R/A Pin = Gnd

-0.4

-0.8

-0.4

-0.8

mA

Remote Activate Voltage

R/A Pin Open

2

6

2

6

V

Reset Current

Reset = Gnd, R/A = Gnd

-0.4

-0.8

-0.4

-0.8

mA

Reset Voltage

Reset open, R/A = Gnd 

2

6

2

6

V

Output Current Rise Time

R

L

 = 50

, T

J

 = 25°C, C

= 0

400

400

mA/

µ

s

Prop. Delay from R/A

R

L

 = 50

, T

= 25°C, C

= 0

300

300

ns

Prop. Delay from O/V input R

L

 = 50

, T

= 25°C, C

= 0

500

500

ns

Comparator Section

Input Threshold (Input

voltage rising on O.V. and

falling on U.V.)

T

J

 = 25°C

2.45

2.50

2.55

2.40

2.50

2.60

V

Over Temperature Range

2.40

2.60

2.35

2.65

V

Input Hysteresis

25

25

mV

Input Bias Current

Sense Input = 0V

-0.3

-1.0

-0.3

-1.0

µ

A

Delay Saturation

0.2

0.5

0.2

0.5

V

Delay High Level

6

7

6

7

V

Delay Charging Current

V

O

 = 0

-200

-250

-300

-200

-250

-300

µ

A

Indicate Saturation

I

= 10mA

0.2

0.5

0.2

0.5

V

Indicate Leakage

V

IND

 = 40V

.01

1.0

.01

1.0

µ

A

Propagation Delay

Input Over Drive = 200mV, T

= 25°C, C

D

 = 0

400

400

ns

Input Over Drive = 200mV, T

= 25°C, C

= 1

µ

F

10

10

ms

Current Limit Section

Input Voltage Range

0

V

IN

 

-3V

0

V

IN

 -

3V

V

Input Bias Current

Offset Pin Open, V

CM

 = 0

-0.3

-1.0

-0.3

-1.0

µ

A

Input Offset Voltage

Offset Pin Open, V

CM

 = 0

0

10

0

10

mV

10k

 from Offset Pin to Gnd

80

100

120

80

100

120

mV

CMRR

 V

CM

 

 12V, V

IN 

=  15V

60

70

60

70

dB

AVOL

Offset Pin Open, V

CM

 = 0V, 

R

= 10k to 15k

,  

V

OUT

 = 1 to 6V

72

80

72

80

dB

Output Saturation

I

= 10mA

0.2

0.5

0.2

0.5

V

Output Leakage

V

IND

 = 40V

.01

1.0

.01

1.0

µ

A

Small Signal Bandwidth

A

V

 = 0dB, T

= 25°C

5

5

MHz

Propagation Delay

V

OVERDRIVE

 = 100mV, T

J

 = 25°C

200

200

ns

ELECTRICAL CHARACTERISTICS:

 Unless otherwise stated, these specifications apply for T

= -55°C to +125°C for the

UC1543 and UC1544; -25°C to +85°C for the UC2543 and UC2544; and 0°C to +70°C for the UC3543 and UC3544. Electrical

tests are performed with V

IN

 = 10V and 2k

 pull-up resistors on all indicator outputs. All electrical specifications for the UC1544,

UC2544, and UC3544 devices are tested with the inverting over-voltage input and the non-inverting under-voltage input externally

connected to the 2.5V reference. T

A

 = T

J.

UC1543 UC1544

UC2543 UC2544

UC3543 UC3544

3

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UC1543 UC1544

UC2543 UC2544

UC3543 UC3544

Note: R

T

 is connected from Offset Pin to Gnd. Values of

R

T

 below 5.0k may cause Amplifier Cutoff at -55

°

C.

SCR Trigger Power Limiting

Current Limit Amplifier Frequency Response

Activation Delay vs Capacitor Value

Comparator Input Hysteresis

Current Limit Input Threshold

Current Limit Amplifier Gain

4

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UNITRODE CORPORATION

7 CONTINENTAL BLVD. 

 MERRIMACK, NH 03054

TEL. (603) 424-2410  

 FAX 603-424-3460

UC1543 UC1544

UC2543 UC2544

UC3543 UC3544

Overcurrent Shutdown

Input Line Monitor

APPLICATIONS (Pin numbers given for UC1543 series devices)

Typical Application

Sensing Multiple Supply Voltages

The values for the external components are determined

as follows:

Current limit input threshold, V

TH

 =  

1000

R

1

C

S

 is determined by the current loop dynamics

Peak current to load, I

P

 

 

V

TH

R

SC

 

+

 

V

O

R

SC

 

2

R

2

 

+

 

3

Short Circuit Current, I

SC

 = 

V

TH

R

SC

Low output voltage limit, V

O

 (Low) = 

2.5 

(

R

4

 

+

 R

5

 

+

 R

6

)

R

5

 

+

 R

6

High output voltage limit, V

O

 (High) = 

2.5 

(

R

4

 

+

 R

5

 

+

 R

6

)

R

6

Voltage sensing delay, t

D

 = 10,000Cd

SCR trigger power limiting resistor, R

G

 > 

V

IN

 

 5

0.2

5

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IMPORTANT NOTICE

Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue

any product or service without notice, and advise customers to obtain the latest version of relevant information

to verify, before placing orders, that information being relied on is current and complete. All products are sold

subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those

pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in

accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent

TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily

performed, except those mandated by government requirements.

CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF

DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL

APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR

WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER

CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO

BE FULLY AT THE CUSTOMER’S RISK.

In order to minimize risks associated with the customer’s applications, adequate design and operating

safeguards must be provided by the customer to minimize inherent or procedural hazards.

TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent

that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other

intellectual property right of TI covering or relating to any combination, machine, or process in which such

semiconductor products or services might be or are used. TI’s publication of information regarding any third

party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.

Copyright 

©

 1999, Texas Instruments Incorporated