Diodes AP2008 User Manual

AP2008

PWM BUCK CONTROLLER

Features

• PWM Buck Control Circuitry

• Operating voltage can be up to 20V

• Under voltage Lockout (UVLO) Protection

• Short Circuit Protection (SCP)

• Soft-start circuit

• Variable Oscillator Frequency -- 300Khz Max

• 0.77V voltage reference Output

• 8-pin SOP package

• SOP-8L: Available in “Green” Molding Compound

(No Br, Sb)

• Lead Free Finish/ RoHS Compliant (Note 1)

Applications

• Backlight inverter

• LCD Monitor

• XDROM, XDSL Product

• DC/DC converters in computers, etc.

Ordering Information

AP 2008 S X - 13

General Description

The AP2008 integrates Pulse-Width-Modulation (PWM) control
circuit into a single chip, mainly designs for power-supply
regulator. All the functions include an on-chip 0.77V reference
output, an error a mplifier, an adjustable oscillator, a soft -start,
UVLO, SCP circuitry, and a push-pull output circuit. Switching
frequency is adjustable by trimming CT. During low VCC situation,
the UVLO makes sure that the outputs are off until the internal
circuit is operational normally.

Package PackingLead Free

S : SOP-8L

L : Lead Free

G : Green

Device

AP2008SL-13 S SOP-8L 2500/Tape & Reel -13

Lead-free

Package

Code

Packaging

(Note 2)

AP2008SG-13 S SOP-8L 2500/Tape & Reel -13

Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html

2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at

http://www.diodes.com/datasheets/ap02001.pdf

.

.

AP2008 Rev. 2 1 of 8 FEBRUARY 2009

www.diodes.com © Diodes Incorporated

13 : Tape & Reel

13” Tape and Reel

Quantity Part Number Suffix

Pin Assignments

( Top View )

AP2008

PWM BUCK CONTROLLER

OUT

VCC

COMP

FB

1

2

3

4

8

7

6

5

SOP-8L

Pin Descriptions

Pin Name Description

OUT PWM Output
VCC Supply Voltage

COMP Feedback Loop Compensation

FB Voltage Feedback

SCP Short Circuit Protection

SS Soft-Start.
CT Timing Capacitor

GND Ground

GND

CT

SS

SCP

AP2008 Rev. 2 2 of 8 FEBRUARY 2009

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Block Diagram

0.77V

VCC

Bandgap

Reference

2.5V

Internal use

UVLO

SS

CT

10K-300KHz / CT value

Oscillator

AP2008

PWM BUCK CONTROLLER

VCC

FB

COMP

Error Amplifier

1.5V

Iss

-

+

0.7V

SCP

-

+

PWM Amplifier

+
+

-

GND

OUT

Absolute Maximum Ratings

Symbol Parameter Rating Unit

VCC Supply voltage 22 V

VI Amplifier input voltage 20 V

VO Collector output voltage VCC-1.0V V

I

Source current 200 mA

SOURCE

I

Sink current 200 mA

SINK

TOP Operati n g t em p e r ature range -20 to +85

T

Storage temperature range -65 to +150

ST

Recommended Operating Conditions

Symbol Parameter Min Max Unit

VCC Supply voltage 3.6 20 V

VI Amplifier input voltage 1.05 1.45 V
VO Collector output voltage Vcc-1.5 V
IFB Current into feedback terminal 45 µA
RF Feedback resistor 100 kΩ
CT Timing capacitor 100 6800 pF

F

Oscillator frequency 10 300 KHz

OSC

o

C

o

C

AP2008 Rev. 2 3 of 8 FEBRUARY 2009

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AP2008

PWM BUCK CONTROLLER

Electrical Characteristics (T

=25ºC, VCC=6V, f=200 Khz)

A

Reference (REF)

Symbol Parameter Conditions Min Typ. Max Unit

Comp connect to FB 0.755 0.770 0.785 V

V

REF

Output voltage change with
temperature

= -20ºC ~ 25ºC -0.1 ±1 %

T

A

TA = 25ºC ~ 85ºC -0.2 ±1 %

Under voltage lockout (UVLO)

Symbol Parameter Conditions Min Typ. Max Unit

VUT Upper threshold voltage (VCC)

I

= 0.1mA

V

Lower th reshold voltage (VCC) 2.4 V

LWT

VHT Hysteresis (VCC) 500 mV

O(REF)

T

= 25ºC

A

2.9 V

Short-circuit protection (SCP) control

Symbol Parameter Conditions Min Typ. Max Unit

VIT Input threshold voltage TA = 25ºC 0.60 0.67 0.75 V

V

Standby voltage No pull up 100 130 160 mV

STB

VLT Latched input voltage No pull up 50 100 mV
I

Input (source) current VI = 0.7V, TA = 25ºC -10 -15 -20 µA

SCP

VCT

Comparator threshold voltage
(COMP)

1.5 V

Oscillator (OSC)

Symbol Parameter Conditions Min Typ. Max Unit

F

Frequency CT =270 pF 200 KHz

OSC

ΔF

OSC

Standard deviation of frequency C
Frequency change with voltage VCC=3.6V ~ 20V 1

=270 pF 10

T

%

Error-amplifier

Symbol

Parameter Conditions Min Typ. Max Unit

VIO Input offset voltage VO (FB)=0.77V ±6 mV

IIO Input offset current VO (FB)=0.77V ±100 nA

IIB Input bias current VO (FB)=0.77V 160 500 nA

VCM Common-mode input voltage range VCC=3.6V ~ 20V 1.05 1.45 V

AV Open-loop voltage amplification RF=200 kΩ 70 80 dB

GBW Unity-gain bandwidth 1.5 MHz

CMRR Common-mode rejection ratio 60 80 dB

VOH Max. output voltage V

-0.1 V

ref

VOL Min. output voltage 1 V

IOI Output (sink) current (COMP) VID = -0.1V, VO = 0.77V 0.5 1.6 mA
IOO Output (source) current (COMP) VID = 0.1V, VO = 0.77V -45 -70 µA

AP2008 Rev. 2 4 of 8 FEBRUARY 2009

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AP2008

PWM BUCK CONTROLLER

Electrical Characteristics (Continued) (T

=25ºC, VCC=6V, f=200 Khz)

A

Output section

Symbol Parameter Conditions Min Typ. Max Unit

I

Leakage current VO = 20V 10 µA

LEAK

Sink current V
Source current VIN= 12V 200 mA

Output saturation voltage IO = 10 mA 1.0 1.5 V

V

I

DRV

SAT

= 12V 200 mA

IN

ISC Short-circuit output current VO = 6V 120 mA

PWM comparator

Symbol Parameter Conditions Min Typ. Max Unit

VT0

V

T100

Input threshold voltage at f = 10 KHz
(COMP)

Maximum duty cycle 1.2 1.3 V

CT=6800pF 0.6 0.7 V

Total device

Symbol Parameter Conditions Min Typ. Max Unit

I

Average supply current CT = 270pF 6 10 mA

CCA

Soft Start

Symbol Parameter Conditions Min Typ. Max Unit

VSS Soft-start Voltage 2.3 V

ISS Constant Charge Current 20 µA

Typical Application Circuit

R3 30K

C2

10nF

(Optional)

4

FB

SCP

5

2

3

VCC

COMP

CT

SS

7

6

1

OUT

GND

8

C4 270pF
C5 50nF
C6 220nF

Q1

P mos

5A

L1

10uH

R1
1K

R2
4K

Vcc = 12V

C1

470uF

C4

50nF

(Optional)

Output

1V/5A

C3

470uF

Step-Down DC/DC converter

AP2008 Rev. 2 5 of 8 FEBRUARY 2009

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A

Typical Characteristics

REFERENCE OUTPUT VOLTAGE

vs.

POWER-SUPPLY VOLTAGE

0.785

0.78

0.775

Vref-

Reference

0.77

0.765

Output

Voltage (V)

0.76

0.755
4 6 8 101214161820

Vcc-Power Supply Voltage (V)

PWM BUCK CONTROLLER

VERAGE SUPPLY CURRENT

vs.

POWER-SUPPLY VOLTAGE

5
4
3
2

(mA)

1

Icc-Average

Supply Current

0

048121620

Vcc - Power-Supply Voltgae (V)

AP2008

AVERAGE SUPPLY CURRENT

vs.

AMBIENT TEMPERATURE

7
6
5

(mA)

- Average

CC

I

4
3

Supply Current

2

-50 -25 0 25 50 75 100

TA - Ambient Temperature (℃)

OSCILLATOR FREQUENCY

vs.

TIMING CAPACITANCE

0

100 600 1100 1600 2100 2600 3100 3600 4100 4600 5100 5600 6100 6600

CT-Timing Capacitor (pF)

fosc - Frequency

350

300

250

200

150

(KHz)

100

50

(V)
V

Period (ms)

tscp-SCP Time-out

V

vs. FREQUENCY

CT

1.6

1.4

1.2
1

0.8

CT

0.6

0.4

0.2
0

0 100 200 300

Frequency (KHz)

SCP TIME-OUT PERIOD

vs.

35
30
25
20
15
10

5
0

45 90 135 180 225 270 315 360 405 450 495

SCP CAPACITANCE

Cscp - SCP Capacitance (nF)

VCT(min)
VCT(max)

AP2008 Rev. 2 6 of 8 FEBRUARY 2009

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Typical Characteristics (Continued)

SOFT-START TIME (Ts )

vs.

SOFT-START CAPACITOR (Css)

30
25
20
15

Ts (mS)

10

5
0

25 50 75 100 125 150 175 200

Css (nF)

AP2008

PWM BUCK CONTROLLER

Marking Information

(1) SOP-8L

Logo

Part Number

( Top View )

8

5

AP2008

YY

WW X

X

41

L : Lead Free

G : Green

YY

: Year : 08, 09,10~
WW : Week : 01~52; 52
represents 52 and 53 week

: Internal Code

X

AP2008 Rev. 2 7 of 8 FEBRUARY 2009

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Package Information (All Dimensions in mm)

(1) Package Type: SOP- 8L

0.254

3.85/3.95

5.90/6.10

0.10/0.20

Detail "A"

0.62/0.82

Gauge Plane
Seating Plane

AP2008

PWM BUCK CONTROLLER

7°~9°

1.27typ

8x-0.60

6x-1.27

8x-1.55

Land Pattern Recommendation

0.3/0.5

4.85/4.95

(Unit: mm)

0.35max.

0.15/0.25

1.30/1.50

1.75max.

5.4

7°~9°

45°

Detail "A"

0°/8°

IMPORTANT NOTICE

Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further
notice to any product herein. Diodes Incorporated does not assume any liability arising out of the application or use of any product described herein; neither
does it convey any license under its patent rights, nor the rights of others. The user of products in such applications shall assume all risks of such use and will
agree to hold Diodes Incorporated and all the companies whose products are represented on our website, harmless against all damages.

LIFE SUPPORT

Diodes Incorporated products are not authorized for use as critical components in life support devices or systems without the expressed written approval of the
President of Diodes Incorporated.

AP2008 Rev. 2 8 of 8 FEBRUARY 2009

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