Panasonic AN8041S Datasheet

Voltage Regulators

AN8041S

Liquid crystal backlight control IC

■ Overview

The AN8041S is an inverter control IC for liquid crystal backlight using PWM method. The output voltage of DC-DC converter and the current of cathode-ray tube can be controlled by using two error amplifiers, so that the system is designed easily.

Since the n-channel MOSFET can be directly driven, it is possible to construct a highly effective power supply.

16 9

18

10.1±0.3

4.2±0.3

6.5±0.3

■ Features

• Operating supply voltage: 3.6 V to 34 V

• Totem pole output circuit: Output current of ±500 mA

• Built-in bootstrap circuit

• N-channel power MOSFET can be directly driven

• Built-in two error amplifier circuits allow both the

voltage and current control

• Incorporating on/off functions (active-high control input, standby mode current is 5 µA or less)

• Built-in timer latch short-circuit protection circuit

• Maximum oscillation frequency: 500 kHz

Note)*: The voltage is limited to the range of 3.6 V to 17 V if used in a step-down circuit.

*

(0.605)

1.27

Seating plane

0.40±0.25

0.1±0.1 1.5±0.2

SOP016-P-0225A

■ Applications

• LCD displays, digital still cameras, and PDAs

(0.15)

0.3

Unit: mm

(0° to 10°)

Seating plane

■ Block Diagram

Off

S.C.P.

16

5

REF

V

1

V

REF

2.57 V

On/off

active-high

R

U.V.L.O.

S

R

Latch

S

12

Q Q

Q

GND

DTC

4

Constant

current source

S.C.P. comp.

CT

3

PWM comp.

2

OSC

RT

Error amp. 1

Error amp. 2

CC

V

15

Bootstrap

14

13

11 10

CB

Out

8

FB1

6

IN+1

7

IN−1

9

FB2 IN+2 IN−2

1

AN8041S Voltage Regulators

■ Pin Descriptions

Pin No. Symbol Description

1V

Reference voltage output pin

REF

2 RT Pin for connecting oscillator

timing resistor

3 CT Pin for connecting oscillator

timing capacitor 4 DTC Dead-time control pin 5 S.C.P. Pin for connecting the time constant

setting capacitor for short-circuit

protection 6IN+1

Error amplifier 1 noninverted input pin

■ Absolute Maximum Ratings

Parameter Symbol Rating Unit

Supply voltage V Off terminal application voltage V Error amplifier input voltage V DTC terminal application voltage V Out terminal application voltage V CB terminal application voltage V Out terminal constant output current I Out terminal peak output current I Power dissipation Operating ambient temperature Storage temperature

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

*

CC

OFF

I

DTC

OUT

CB

O

O(PEAK)

P

D

T

opr

T

stg

Pin No. Symbol Description

7IN−1 Error amplifier 1 inverted input pin 8 FB1 Error amplifier 1 output pin 9 FB2 Error amplifier 2 output pin

10 IN−2 Error amplifier 2 inverted input pin 11 IN+2

Error amplifier 2 noninverted input pin 12 GND Grounding pin 13 Out Output pin 14 CB Bootstrap output circuit 15 V

Power supply voltage application pin

CC

16 Off On/off control pin

35 V 35 V

− 0.3 to V

REF

35 V 35 V

±100 mA ±500 mA

143 mW

−30 to +85 °C

−40 to +125 °C

V V

■ Recommended Operating Range

Parameter Symbol Range Unit

Supply voltage (when using step-down circuit) V Supply voltage (when using step-up circuit) V Oscillation frequency f Oscillator timing resistance R Oscillator timing capacitance C Error amplifier input voltage V Reference voltage output current I

2

CC

OUT

IN

REF

3.6 to 17 V

3.6 to 34 V 5 to 500 kHz

T

5.1 to 30 kΩ

100 to 10 000 pF

− 0.1 to +0.8 V

−1 to 0 mA

Voltage Regulators AN8041S

■ Electrical Characteristics at VCC = 12 V, RT = 15 kΩ, CT = 120 pF, Ta = 25°C

Parameter Symbol Conditions Min Typ Max Unit

Reference voltage block

Output voltage V

REFIREF

Input regulation with input fluctuation Line VCC = 3.6 V to 34 V  725mV Load regulation Load I Output voltage V

TC1Ta

temperature characteristics 1 Output voltage V

TC2Ta

temperature characteristics 2 Output short-circuit current I

OS

U.V.L.O. block

Circuit operation start voltage V Hysteresis width V

UON

HYS

Error amplifier block

Input offset voltage V Input bias current I Common-mode input voltage range V High-level output voltage 1 V Low-level output voltage 1 V Output sink current I Output source current I Open-loop gain A

IO

B

ICR

EH

EL

SINK

SOURCEVFB

G

Dead-time control circuit block

Input current I Low-level input threshold voltage V High-level input threshold voltage V

DTC

DT-L

DT-H

Output block

Oscillation frequency f

OUT

Output duty ratio Du R Low-level output voltage V High-level output voltage V Frequency f

OLIO

OHIO

dV

supply voltage characteristics VCC = 3.6 V to 34 V Frequency f

dT1fOUT

temperature characteristics 1 Ta = −30°C to +25°C Frequency f

dT2fOUT

temperature characteristics 2 Ta = 25°C to 85°C

= −1 mA 2.483 2.57 2.647 V

= − 0.1 mA to −1 mA  110mV

REF

= −30°C to +25°C ±1  %

= 25°C to 85°C ±1  %

−10  mA

2.8 3.1 3.4 V 60 140 220 mV

−6  6mV

−500 −25  nA

− 0.1  0.8 V

V

REF

− 0.3 V

REF

− 0.1

 V

 0.1 0.3 V

VFB = 0.9 V  8  mA

= 0.9 V −110 µA

 70  dB

RT = 15 kΩ−14.8 −12.3 −9.8 µA Duty = 0%  0.45 0.65 V Duty = 100% 1.2 1.4  V

RT = 15 kΩ, 180 200 220 kHz CT = 120 pF

= 75 kΩ 45 50 55 %

DTC

= 70 mA  1.0 1.3 V = −70 mA VCB−2.0 VCB−1.0  V

f

= 200 kHz, ±3  V

OUT

= 200 kHz, ±9  V

3

AN8041S Voltage Regulators

■ Electrical Characteristics at VCC = 12 V, RT = 15 kΩ, CT = 120 pF, Ta = 25°C (continued)

Parameter Symbol Conditions Min Typ Max Unit

Bootstrap circuit block

Input standby voltage V

Oscillator block

RT terminal voltage V

Short-circuit protection block

Input threshold voltage V Input standby voltage V Input latch voltage V Charge current I Comparator threshold voltage V

On/off control block

Threshold voltage V

Whole device

Total consumption current I Standby current I

CC(SB)

INCBICB

RT

THPC

STBY

IN

CHG

THL

TH

CC

= −70 mA

VCC−1.2 VCC−1.0 VCC− 0.8

 0.37  V

0.70 0.75 0.80 V

 30 120 mV  30 120 mV

−2.76 −2.3 −1.84 µA  1.82  V

0.8  2.0 V

 3.9 5.0 mA  5 µA

V

■ Terminal Equivalent Circuits

Pin No. Equivalent circuit Description I/O

1V

V

CC

1

2 RT: 

3 CT: 

V

REF

V

REF

To PWM input

OSC comp.

100 Ω

2

RT (≈ 0.37 V)

DTC S.C.P.

I

O

3

2I

O

:O

REF

The reference voltage output terminal (2.57 V (allowance: ±3%)). Incorporating short-circuit protection against GND.

The terminal used for connecting a timing resistor to set oscillator's frequency. Use a resistance value within the range of 5.1 kΩ to 30 kΩ. The terminal voltage is approx. 0.37 V.

The terminal used for connecting a timing capacitor to set oscillator's frequency. Use a capacitance value within the range of 100 pF to 10 000 pF. For frequency setting method, refer to the " Application Notes, [3] Function descriptions " section. Use an oscillation frequency in the range of 5 kHz to 500 kHz.

4

Voltage Regulators AN8041S

■ Terminal Equivalent Circuits (continued)

Pin No. Equivalent circuit Description I/O

4 DTC: 

5 S.C.P.: 

6IN+1: I

7IN−1: I

8 FB1: O

9 FB2: O

V

REF

RT

V

REF

I

CHG

To U.V.L.O.

V

REF

V

REF

V

REF

The terminal for connecting a resistor and ca-

PWM comparator input

I

4

DTC

C

DTC

R

DTC

pacitor to set the dead-time and soft start period of PWM output. Input current I

is determined

DTC

by the timing resistor RT , so that dispersion and fluctuation with temperature are suppressed. It is approx. −12.3 µA when R

V

=

RT

×1[A]

RT2

I

DTC

= 15 kΩ.

T

The terminal for connecting a capacitor to set the time constant of soft start and timer latch shortcircuit protection circuit.

0.75 V

Latch

S R

Q

Use a capacitance value in the range of more than 1 000 pF. The charge current I

is determined by the

CHG

timing resistor RT , so that dispersion and fluctuation with temperature are suppressed. It is

5

approx. −1.3 µA when R

V

=

RT

×1[A]

RT11

I

CHG

= 15 kΩ.

T

The noninverted input terminal of the error amplifier 1. For common-mode input, use in the range of

− 0.1 V to +0.8 V.

The inverted input terminal of the error amplifier 1.

67

For common-mode input, use in the range of

− 0.1 V to +0.8 V.

The output terminal of the error amplifier 1.

Source current

8

Sink current

Source current: approx. −120 µA Sink current : approx. 8 mA Correct the frequency characteristics of the gain and the phase by connecting a resistor and a capacitor between this terminal and IN−1 terminal.

The output terminal of the error amplifier 2.

Source current

9

Sink current

Source current: approx. −120 µA Sink current : approx. 8 mA Correct the frequency characteristics of the gain and the phase by connecting a resistor and a capacitor between this terminal and IN−2 terminal.

5