Texas Instruments UC3584DWTR, UC3584N Datasheet

UC1584
UC2584
UC3584

03/99

FEATURES

• Practical Operation at Switching
Frequencies up to 1MHz

• Wide Band Error Amplifier

• Undervoltage Lockout with Hysteresis

• Output Active Low During UVLO

• Soft Start/Maximum Duty Cycle

Control

• Trimmed Bandgap Reference

• Internally Regulated 15V Boost

Supply

• Short Circuit Protection with
Programmable Delay

Secondary Side Synchronous Post Regulator

DESCRIPTION

The UC3584 is a low voltage, Secondary Side Synchronous Post Regula­tor. It is intended to be used for auxiliary output voltage regulation in single
secondary winding, multiple output power supplies (for more details refer
to the Application Section of this Data sheet). The UC3584 is most suited
for systems where the main output is regulated between 5V and 14V. Out­put voltages regulated by the UC3584 can range from virtually 0V up to
the output voltage of the main output.

Auxiliary output voltage regulation with the UC3584 uses leading edge
modulation making it compatible to primary side peak current or voltage
mode control. The UC3584 clock circuit is synchronized to the switching
frequency utilizing the falling edge of the transformer’s secondary winding
waveform.

15

13

14

16

11

9

10

12

SYNC

CT

RT

VREG

VCC

220pF

15kΩ

100pF

1kΩ

BST2

PGND

FB

BST1

0.1µF

1N4148

0.1µF

10µF

SOLID

TANTALUM

+

1N4148

33µH

COLTRONICS

470µF

+

2

4

3

1

6

8

7

5

COMP

SS

CDLY

GND

SRC

OUT

VFLT

1.5µF

120pF

1000pF

0.1µF

3300pF

20kΩ

30.1kΩ

1500pF

1.33kΩ

24.3kΩ

3.3V
AUX

100Ω

1.5W

0.1µF

390µF

33µH

COILTRONICS

CSHD

10-45L

IRFR024

4.75kΩ

3.57kΩ 3.3Ω

++++

7µH

OS-CON

330µF

+

1µF

+

5V
MAIN

170kHz

PUSH-PULL

2

210

10

10BQ040

TYPICAL APPLICATION DIAGRAM.

UDG-99062

2

UC1584
UC2584
UC3584

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V

V

FLT

Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 50V, 30V at 2A

Supply Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA

Analog Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 to 20V

SYNC Maximum Sink Current. . . . . . . . . . . . . . . . . . . . . 600µA

PWM Driver, I

OUT

. . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 300mA

PWM Driver, I

OUT

(Peak). . . . . . . . . . . . . . . . . . . . . . . . . ± 1.5A

Maximum Operating Frequency . . . . . . . . . . . . . . . . . . . . 1MHz

Power Dissipation at T

A

= 60°C . . . . . . . . . . . . . . . . . . . . . . 1W

Storage Temperature . . . . . . . . . . . . . . . . . . . . –65°C to 150°C

Junction Temperature. . . . . . . . . . . . . . . . . . . . –55°C to 150°C

Lead Temperature (Soldering, 10 sec.). . . . . . . . . . . . . . 300°C

Currents are positive into, negative out of specified terminal.
Consult Packaging Section of Databook for thermal limitations
and considerations of packages.

CONNECTION DIAGRAMS

DIL-16, SOIC-16 (Top View)
J, N or DW Packages

ELECTRICAL CHARACTERISTICS: Unless otherwise specified, T

A

= 0°C to 70°C for the UC3584, –40°C to 85°C for

the UC2584, and –55°C to 125°C for the UC1584, VCC = 15V. TA=TJ.

PARAMETERS TEST CONDITIONS MIN TYPE MAX UNITS

Error Amplifier

FB COMP = FB 1.468 1.5 1.532 V
I

FB

V

COMP=VFB

150 300 450 nA

COMP V

OL

FB = 1.6V, I

COMP

= 200µA 50 400 mV

COMP V

OH

FB = 1.4V, I

COMP

= –200µA 5.1 5.5 7 V
AVOL 60 80 dB
PSRR (COMP) COMP = FB, VCC = 14V to 16V 60 dB
GBW Product F = 100kHz 5 10 MHz

Oscillator

Frequency R

T

= 3.75k, CT= 400pF, No Synchronization 500 kHz
Ramp Low RT= 3.75k, CT= 400pF, No Synchronization 1.75 V
Ramp High RT= 3.75k, CT= 400pF, No Synchronization 3.5 V
Ramp Amplitude RT= 3.75k, CT= 400pF, No Synchronization 1.75 V

PWM

Maximum Duty Cycle COMP = 4.5V 90 %
Minimum Duty Cycle COMP = 0V 0 %

PWM DRIVER

V

SAT

High V

FLT–VOUT,IOUT

= –100mA 2.5 3 V

V

SAT

Low V

OUT–VSRC,IOUT

= 50mA 0.8 2.2 V

T

RISE

Load = 1nF, SRC = 0V, Measure V

OUT

1V to 9V 75 100 ns

T

FALL

Load = 1nF, SRC = 0V, Measure V

OUT

9V to 1V 25 100 ns

TEMPERATURE RANGE PACKAGE

UC1584J –55°C to +125°C CDIP
UC2584DW –40°C to +85°C SOIC-Wide
UC2584N PDIP
UC3584DW 0°C to +70°C SOIC-Wide
UC3584N PDIP

ORDERING INFORMATION

3

UC1584
UC2584
UC3584

ELECTRICAL CHARACTERISTICS:

Unless otherwise specified, TA= 0°C to 70°C for the UC3584, –40°C to 85°C for the

UC2584, and –55°C to 125°C for the UC1584, VCC = 15V. TA=TJ.

PARAMETERS TEST CONDITIONS MIN TYPE MAX UNITS

Soft Start

Charge Current 30 µA
Discharge Current 1mA
SS Delay C

SS

= 500nF 50 ms

Fault Latch

Charge Current 30 µA
Discharge Current 5mA
Fault Latch Delay CDLY = 500nF 50 ms

UVLO

VCC On 10.5 V
Hysteresis 1.7 V

Regulated Voltage

V

REG

I

REG

= 0mA to 1mA 4.8 5.2 V

VCC Regulator

VCC Boost inductor connected to 5V 14 15 16 V
I

CC

No Load, Boost Circuitry Inactive 12 40 mA
No Load, Boost Circuitry Active (Note 1) 55 mA

Note 1: Guaranteed by design. Not 100% tested in production.

BLOCK DIAGRAM

UDG-97141