Panasonic AN8038S, AN8038 Datasheet

Voltage Regulators

AN8038, AN8038S

AC-DC switching power supply control IC
with RCC local resonance circuit for
improved conformance with
energy conservation laws

■ Overview

The AN8038 and AN8038S are self-excited AC-DC
switching power supply control IC that adopt RCC local
resonance control. These ICs are designed to achieve high
efficiency over a wide range of loads (light loads at the
standby mode to heavy loads) for improved conformance
with energy conservation laws, and support input levels
used worldwide. They are particularly appropriate for use
in AV and OA equipments.

■ Features

• Supports improved conformance with energy conser-

vation laws by providing two operating modes.

With external resistors, it is possible to set the operating

point at which the modes change over according to the

load power, as shown below.

1.Continuous (RCC) mode
High efficiency achieved with local resonance opera­tion (zero cross detection).

2.Discontinuous mode (standby) mode
Reduced switching loss and standby power due to re­duced frequency

• Input voltage correction function. This function corrects

the maximum on-period in a manner inversely propor­tional to the input voltage.

• Built-in overvoltage protection function (detects at V

• Pulse-by-pulse overcurrent protection function (single detection per one cycle)

• Packages: 8-pin DIP ··· AN8038

8-pin SOP··· AN8038S

CC

pin)

AN8038 Unit: mm

3° to 15°

AN8038S Unit: mm

(0.60)

1
2
3

9.4±0.3

4

6.3±0.3

7.62±0.25

DIP008-P-0300B

5.01±0.20

1.27

0.10
Seating plane

SOP008-P-0225C

8
7
6
5

0.51 min.

3.8±0.25

.1

0

+

5

.0

0

–

0.15

58

0.15±0.10

6.40±0.20

4.30±0.20

41

1.75 max.

1.45±0.10

+0.10

0.40

–0.05

(3.45)

(1.05)

0.5±0.1

0° to10°

0.50±0.20

1.2±0.25

2.54

■ Applications

• Facsimiles and other OA equipment

• Printers and other personal computer peripheral equipment

• AV equipment

1

AN8038, AN8038S Voltage Regulators

■ Block Diagram

CC

V

8

RSTB

IFB

TR

2

4

High-side

1

Low-side

OVP

17.5

kΩ

17.5

kΩ

I/V

conv .

clamp

clamp

7 V

4.2 V

OVP

S

V

FB

Current

reviser (ITR)

0.25 V

(SD latch)

RQ

S

(TR latch)

INIT

R

Q

Current

reviser (IFB)

1.0 V

Start
Stop

3

V

REF

7 V

Q

In
In

Q

Out

7

Out

6

GND

drive
Q
Q

Q

CF

latch

Q

T

ON

S

T

OFF

R

R

5

CLM

− 0.2 V

CF

2

Voltage Regulators AN8038, AN8038S

■ Pin Descriptions

Pin No. Symbol Description

1 TR Transformer reset. When a transformer reset is detected, i.e., a low level is input to this pin, the IC

output goes high.
However, the transformer reset signal is ignored during the minimum off-period determined by
the CF pin. The maximum on-period is also corrected according to the current flowing out of this
pin.

2 RSTB Adjusts the light-load detection level that determines the when the IC switches from RCC to

discontinuous operation. When the voltage (V
signal from IFB pin goes up higher than this pin, minimum off-period current at CF pin decreases,
and operating frequency decreases.

The detection level can be adjusted arbitrarily using an external pull-down resistor.
3 CF Connection for the capacitor that determines the on and off periods for the IC output (Out).
4 IFB Input for the current feedback signal from the power supply output photocoupler
5 CLM Input of the pulse-by-pulse overcurrent protection circuit. Normally, it will be necessary to add

an external filter for this input.
6 GND Ground
7V
8V

Output to drive a power MOSFET directly

OUT

Power supply. This pin watches VCC , and has operating threshold voltages for the start, stop,

CC

OVP, and OVP reset levels.

) which is I-V conversion of current feedback

FB

■ Absolute Maximum Ratings

Parameter Symbol Rating Unit

Supply voltage V
Peak output current I

CC

OP

28 V

−1, +2A

Power dissipation AN8038 PD (Ta = 25°C) 500 mW
(Independent IC PD (Ta = 85°C) 260

1

without a heat sink) AN8038S PD (Ta = 25°C) 306

PD (Ta = 85°C) 122
Operating temperature T
Storage temperature T

Note) *1: When mounted on a printed circuit board: 477 mW

2: When mounted on a printed circuit board: 191 mW

*

opr

stg

*

2

*

−30 to +85 °C

−55 to +150 °C

■ Recommended Operating Range

Parameter Symbol Range Unit

Supply voltage V

From the stop voltage to the OVP operating voltage V

CC

3

AN8038, AN8038S Voltage Regulators

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

Parameter Symbol Conditions Min Typ Max Unit

Low voltage protection (U.V.L.O.) Start V
initial startup supply voltage.

Low voltage protection (U.V.L.O.) Stop V
operation stop supply voltage

Overvoltage protection (OVP) OVP V
operating supply voltage

Overvoltage protection (OVP) OVPC V
release supply voltage

Overvoltage protection (OVP) OVP I
operating time circuit current 1

Overvoltage protection (OVP) OVP I
operating time circuit current 2

Transformer reset detection (TR) TR V
threshold voltage

Transformer reset detection (TR) TR V
upper limit clamp voltage

Transformer reset detection (TR) TR V
lower limit clamp voltage

Transformer reset detection (TR) TR I
pin source current

Overcurrent protection (CLM) CLM V
threshold voltage

Oscillator (CF) maximum CF GI
on-period current gain

Oscillator (CF) maximum CF I
on-period current

Oscillator (CF) minimum CF I
off-period current 1

Oscillator (CF) minimum CF I
off-period current 2

Output oscillator frequency f

Standby pin (RSTB) voltage V
Standby operation (RSTB) RSTB V

threshold voltage
Current feedback pin (IFB) voltage V
Pre-startup low-level output voltage STB V
Low-level output voltage V
High-level output voltage V
Circuit current during startup 1 I

START1

Circuit current 1 OPR1 I
Circuit current 2 OPR2 I

4

CC

CC

CC

CC

CC1

CC2

TH

CLHITR

CLLITR

TR

TH

ONIFB

ON

OFF1IIFB

OFF2IIFB

OSC

RSTB

TH

IFB

OL

OL

OH

CC1VCC

CC2VCC

VCC = 22 V → 10 V 0.4 0.53 0.66 mA

VCC = 22 V → 18 V 1.3 1.7 2.1 mA

= 1 mA 1.2 1.5 1.8 V

= −1 mA − 0.3 − 0.15 0 V

VTR = 0.5 V −50µA

= Open 0.8 1.0 1.2 

ITR = 0 mA 210 280 350 µA

= − 0.7 mA −1 560 −1 250 −940 µA

= −1.3 mA −70 −55 −40 µA

CF = 1 000 pF, ITR = −450 µA 105 140 175 kHz
I

= − 0.5 mA

IFB

I

= − 0.7 mA 5 5 .6 6 .2 V

IFB

VCC = 12 V  1.0 1.25 V
I

= 0.2 A  0.9 2.0 V

OUT

I

= − 0.1 A 15.5 16.3  V

OUT

= 10 V 6.1 8.7 11.3 mA
= 18 V 6.4 9.1 11.8 mA

12.9 14.4 15.9 V

8.0 8.9 9.8 V

18.7 20.5 22.3 V

6.6 7.5 8.4 V

0.15 0.25 0.35 V

−225 −205 −185 mV

3.2 3.5 3.8 V

0.3 0.5 0.7 V

120 190 280 µA

Voltage Regulators AN8038, AN8038S

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

•

Design Reference Data

Note) The characteristics listed below are theoretical values based on the IC design and are not guaranteed.

Parameter Symbol Conditions Min Typ Max Unit

Low-voltage protection (U.V.L.O.) ∆V
start/stop supply voltage difference

Transformer reset (TR) detection TR ∆V
threshold hysteresis width

Oscillator (CF) upper limit voltage V
Oscillator (CF) lower limit voltage 1 V
Oscillator (CF) lower limit voltage 2 V
Maximum on-period t

Minimum off-period 1 t

Minimum off-period 2 t

Light-load oscillator frequency f

CLH

CFL1

CFL2

ON(max)

OFF(min)1IIFB

OFF(min)2IIFB

OSC2

Output rise time t
Output fall time t
TR output response time t
CLM output response time t
Circuit current during startup 2 I

TR

CLM

START2

CC

TH

I

= − 0.5 mA, CF = 1 000 pF  4.2  V

IFB

I

= − 0.5 mA, CF = 1 000 pF  1.0  V

IFB

I

= − 0.2 mA, CF = 1 000 pF  0.1  V

IFB

I

= − 0.2 mA, CF = 1 000 pF  12 µs

IFB

VTR = 0.1 V

= − 0.2 mA, CF = 1 000 pF  2.6 µs

VTR = 0.1 V

= −1.3 mA, CF = 1 000 pF  67 µs

ITR = −450 µA
I

= −1.3 mA, CF = 1 000 pF  15  kHz

IFB

ITR = −450 µA

r

f

10% to 90%, I
10% to 90%, I

= 0 mA  40  ns

OUT

= 0 mA  20  ns

OUT

Ta = −30°C to +85°C 100 190 300 µA

 5.4  V

 0.1  V

 400  ns
 100  ns

■ Terminal Equivalent Circuits

Pin No. Equivalent Circuit Description I/O

1 TR: I

V

REF

7 V

TR

1

High-side

clamp

Low-side

clamp

Transformer reset detection input.
When a transformer reset is detected, i.e., a low
level is input to this pin, the IC output goes high.
However, the transformer reset signal is ignored
if the signal is shorter than the minimum off­period determined by the C

pin. Also note that

F

the maximum on-period is corrected according
to the source current.

5

AN8038, AN8038S Voltage Regulators

■ Terminal Equivalent Circuits (continued)

Pin No. Equivalent Circuit Description I/O

2 RSTB: 

Adjusts the light-load detection level that deter-

V

REF

17.5 kΩ

RSTB

Comp.

CF

17.5 kΩ

2

mines the time when the IC switches from RCC
to discontinuous operation. When the voltage
which is I-V conversion of current feedback sig­nal goes up higher than this pin, operating fre­quency is reduced.
An arbitrary level can be set by inserting an
external pull-down resistor.

3 CF: 

V

REF

I

OFF

Connection for the capacitor that determines the
on- and off-periods of the IC output (Out).

Comp.

The on- and off-periods are corrected by I
which is proportional to the flowing out cur-

V

FB

I

3

ON

rent at the TR pin, and I
to the current at IFB pin.

which corresponds

OFF

ON

CF

4 IFB: I

V

REF

× 5× 1

Connection for the photocoupler used for the
power supply output error-voltage feedback.
This input can decrease the photocoupler dark

V

FB

20 kΩ 1 kΩ

current by about 250 µA.

4

IFB

5 CLM: I

V

REF

Input to the pulse-by-pulse overcurrent protec­tion circuit. Normally, we recommend adding

Comp.

an external filter for this input.

5

CLM

6 GND: 

GND

6

IC ground.

6

Voltage Regulators AN8038, AN8038S

■ Terminal Equivalent Circuits (continued)

Pin No. Equivalent Circuit Description I/O

7V

V

CC

:I

OUT

Output used to directly drive a power MOSFET.
A totem pole structure is adopted in this output
circuit.
The absolute maximum ratings for the output

7

V

OUT

current are:
Peak: +2 A, −1 A
DC: +200 mA, −100 mA

8V

V

CC

8

: 

CC

Power supply.
This pin monitors supply voltage and has the
threshold for the start, stop, OVP, and OVP
reset levels.

■ Usage Notes

The circuit current during startup is set to a low level to minimize power loss due to the startup resistor. However,

V

ripple caused by the power transistor switching on and off may result in incorrect operation of the U.V.L.O. circuit

CC

and failure to start.

The figure shows the allowable range for V

V

ripple so that it remains within the allowable range.

CC

ripple. Insert a capacitor near the IC's V

CC

and GND pins to reduce

CC

3

2.5

2

1.5

ripple amplitude (V[p-p])

1

CC

V

0.6

0.5

0

Recommended
operating range

10

Allowable VCC ripple range

70 100 300 1 000 10 000

VCC ripple frequency (kHz)

7