Panasonic AN8028 Datasheet

Voltage Regulators

AN8028

Self-excited RCC pseudo-resonance type
AC-DC switching power supply control IC

23.3±0.3

2.4±0.25

6.0±0.3

9
8
7
6
5
4
3
2

1

SIP009-P-0000C

+0.1

0.3

–0.05

■ Overview

The AN8028 is an IC developed for controlling the
self-excited switching power supply employing the RCC
pseudo-resonance type control method.

It is compact, equipped only with the necessary mini­mum functions.

The maximum on-period and the minimum off-pe­riod can be set separately by using the external capacitor
and resistor respectively.

It is suitable for the power supply of AV equipment.

■ Features

• Operating supply voltage range:

Stop voltage (8.6 V typical) to 34 V

• Output block employs the totem pole system.

• Power MOSFET can be directly driven.
(output peak current: ±1 A maximum)

• Small pre-start operating current (95 µA typical) allows using a small size start resistor.

• Built-in pulse-by-pulse overcurrent protection function

• Incorporating the protection circuit against malfunction at low voltage (start/stop: 14.9 V/8.6 V)

• Built-in overvoltage protection function (externally resettable)

• Built-in timer latch function

• Equipped with frequency (VF) control function.

• 9-pin single inline package expands the freedom of board design

3.3±0.25

0.5±0.1

2.54

1.5±0.25

1.5±0.25

3.0±0.3

Unit: mm

30°

1.4±0.3

■ Applications

• Televisions, facsimiles, printers, scanners, video equipment

2

TOFF

CC

V

7

Switch
diode

0.1 V

0.32 V

■ Block Diagram

TIM/OVP

FB

TDL

U.V.L.O.

8.6V1.5

8

9

1

Low-side

clamp

0 V

Signal

V

V

REF

(7.1 V)

TIM

High-side

clamp

2.8 V

Current source

I

FB

3

TON

0.7 V

Q
RS

latch
R

S

Q

CLM

6

IN
IN

V

OUT

5

GND

4

CLM

1

AN8028 Voltage Regulators

■ Pin Descriptions

Pin No. Symbol Description

1 TDL Transformer reset detection
2 TOFF Pin for connecting C and R to set minimum off-period
3 TON Pin for connecting C to set minimum on-period
4 CLM Input pin for overcurrent protection detection
5 GND Grounding pin
6V

OUT

7VCCPower supply voltage pin
8 TIM/OVP Pin for use both overvoltage protection circuit and timer latch
9 FB Photocoupler connection pin for error voltage feedback

■ Absolute Maximum Ratings

Parameter Symbol Rating Unit

Supply voltage V
Peak output current I
Power dissipation P
Operating ambient temperature
Storage temperature

Note)*: Expect for the operating ambient temperature and storage temperature, all ratings are for Ta = 25°C.

*

Output pin

*

CC

6PEAK

D

T

opr

T

stg

35 V
±1A

874 mW

−30 to +85 °C

−55 to +150 °C

■ Recommended Operating Range

Parameter Symbol Range Unit

Supply voltage V

CC

■ Electrical Characteristics at VCC = 18 V, Ta = 25°C

Parameter Symbol Conditions Min Typ Max Unit

U.V.L.O. start supply voltage V
U.V.L.O. operation stop supply voltage V
U.V.L.O. start to stop supply voltage ∆V
OVP operation threshold voltage V
OVP release voltage V
OVP operating circuit current 1 I
OVP operating circuit current 2 I
TDL threshold voltage V
TDL upper limit clamp voltage V
TDL lower limit clamp voltage V
CLM threshold voltage V

7START

7STOP

7

8OVP

7OVP

7OVP1VCC

7OVP2VCC

1TDL

1TDL/H ITDL

1TDL/L ITDL

4CLM

= 9.1 V, V
= 20 V, V

= 3mA 2 2.8 3.6 V
= −3mA − 0.3 0 0.3 V

From stop voltage to 34 V

13.4 14.9 16.4 V

7.7 8.6 9.5 V

5.7 6.3 6.9 V

6.1 7.3 8.5 V

7.4 8.2 9 V

= 8.5 V 0.56 0.79 1.02 mA

OVP

= 8.5 V 5.9 7.7 9.5 mA

OVP

0.22 0.32 0.42 V

−220 −200 −180 mV

2

Voltage Regulators AN8028

■ Electrical Characteristics at VCC = 18 V, Ta = 25°C (continued)

Parameter Symbol Conditions Min Typ Max Unit

TON maximum on-period current I

TON upper limit voltage V
TON lower limit voltage V
TOFF upper limit voltage V
TOFF lower limit voltage V
Output oscillation frequency f

Output current feedback current gain G
Pre-start low-level output voltage V
Low-level output voltage 1 V
Low-level output voltage 2 V
High-level output voltage 1 V
High-level output voltage 2 V
Pre-start circuit current I
Circuit current 1 I

Circuit current 2 I

7OPR(1)VCC

7OPR(2)VCC

TDL flowing-out current I

3TON/H

3TON/L

2TOFF/H

2TOFF/L

FB terminal = open −135 −110 −85 µA

3TON

TON terminal = GND
FB terminal = open 0.55 0.7 0.85 V
FB terminal = open − 0.1 0.05 0.2 V

0.7 0.9 1.1 V

− 0.1 0.05 0.2 V

CON = 2 200 pF, R

OSC

C

OFF

IFBIFB

6STB/LVCC

6L(1)IOUT

6L(2)IOUT

6H(1)IOUT

6H(2)IOUT

7STBVCC

= 1 000 pF

= −1 mA 5.05 6.8 8.55 

= 10 V, I

= 10 mA  0.9 2 V
= 100 mA  1.1 2.2 V
= −10 mA 15.7 16.5  V
= −100 mA 15.5 16.3  V

= 12V 55 95 135 µA

= 1.5 kΩ 55 65 75 kHz

OFF

= 10 mA  1 1.25 V

OUT

= 18 V 8.55 11.5 14.3 mA
TON terminal = GND
FB terminal = open

= 34 V 9.6 12.5 15.4 mA
TON terminal = GND
FB terminal = open

V

1TDL

= 0.5 V −50µA

TDL

■ Terminal Equivalent Circuits

Pin No. Equivalent circuit Description I/O

1 TDL: I

2 TOFF: 

V

REF

Transformer reset detection terminal.
When the transformer reset is detected and low

1

High-

side

clamp

Low-

side

clamp

is inputted into the terminal, the output of the IC
(V

) becomes high. However, low-level sig-

OUT

nal under the minimum off-period determined
by the T

is ignored.

OFF

Terminal for connecting the resistor and capaci-

V

CC

tor for determining the minimum off-period (low)
of the IC output (V

OUT

).

An equation for approximate calculation of the

Comp.

0.1 V

2

minimum off-period (T

T

= 2.2 × C × R

OFF

) is as follows:

OFF

C: External capacitance
R: External resistance

3

AN8028 Voltage Regulators

■ Terminal Equivalent Circuits (continued)

Pin No. Equivalent circuit Description I/O

3 TON: 

V

REF

Comp.

0.7 V

V

CC

Terminal for connecting the capacitor for deter­mining the maximum on-period (high) of the IC
output (V

). An equation for approximate

OUT

calculation of the maximum on-period (TON) is
as follows:

T

= 6 500 × C

3

FB

ON

C: External capacitance

4 CLM: I

V

REF

Input terminal for detection of the pulse-by­pulse overcurrent protection.

Comp.

Normally, it is recommended that a filter be
attached externally.

(−)

4

5 GND: 

5

6V

V

CC

Grounding terminal.

:O

OUT

Output terminal for directly driving the power
MOSFET.
It uses the totem pole type output.

6

The maximum rating of the output current:

Peak: ±1 A
DC: ±150 mA

7V

: 

CC

Terminal for applying power supply voltage.

7

It monitors the supply voltage and has the opera­tion threshold of start/stop/OVP reset.

4