AP2003

Synchronous PWM Controller

(Preliminary)

This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of
this product. No rights under any patent accompany the sale of the product.

Rev. 0.1 Feb.10, 2004

1/6

Features

- Single or Dual Supply Application
- 0.8V + 1.0% Voltage Reference.
- Fast transient response.
- Synchronous operation for high efficiency (95%)
- Soft Start functions
- Small size with minimum external components
- Industrial temperature range
- Under Voltage Lockout function
- SOP-8L package

Applications

- Microprocessor core supply
- Low cost synchronous applications
- Voltage Regulator Modules (VRM)
- DDR termination supplies
- Networking power supplies
- Sequenced power supplies

General Description

The AP2003 is a low-cost, full featured, and
synchronous voltage-mode controller designed for
use in single ended power supply applications
where efficiency is of the primary concern. This
synchronous operation allows the elimination of
heat sinks in many applications. The AP2003 is
ideal for implementing DC/DC converters needed to
power advanced microprocessors in low cost
systems, or in distributed power applications where
efficiency is important. Internal level-shift,
high-side drive circuitry, and preset shoot-thru
control, allows the use of inexpensive N-channel
power switches.
AP2003 features include temperature compensated
voltage reference, an internal 200KHz virtual
frequency oscillator, under-voltage lockout
protection, soft-start, and shutdown function.

Pin Assignment

SOP-8L

3
4

(Top View)

VCC

GND

AP2003

DRVH

DRVL

BSTH

SENSE

SS/SHDN

COMP

Ordering Information

AP2003 X X X

Package

Packing

S: SOP-8L

Blank : Tube

A : Taping

Lead Free

Blank : Normal

L : Lead Free Package

Pin Descriptions

Name

Description

VCC Chip

supply

voltage

DRVH

High side driver output

DRVL

Low side driver output

BSTH

Bootstrap, high side driver

SENSE

Voltage sense input

COMP Compensation

SS/

SHDN

Soft start, a capacitor to ground sets
the slow start time

GND Ground

AP2003

Synchronous PWM Controller

(Preliminary)

Anachip Corp.
www.anachip.com.tw Rev. 0.1 Feb.10, 2004

3/6

Electrical Characteristics

Unless specified: V

= 12V; GND = 0V; FB = V

; V

BSTH-GND

= 12V; T

= 25

Symbol

Parameter

Conditions

Min.

Typ.

Max.

Unit

Power Supply

Supply

Voltage

4.2

Supply

Current

6 10 mA

LINE

Line Regulation

VO = 2.5V

0.5

Error Amplifier

Gain

)

50 dB

Input

Bias

5 8 uA

Oscillator

OSC

Oscillator

Frequency

180 200 220 KHz

MAX

Oscillator Max Duty Cycle

Mofset Drivers

DRVH

Source/Sink

BSTH

� V

DRVH

=4.5V

DRVH

� V

PHASE

= 2V

1 A

DRVL

Source/Sink

BSTH

� V

DRVL

= 4.5V

DRVL

� V

GND

= 2V

1 A

Protection

DEAD

Dead

Time

45 100 nS

Reference

Reference

Voltage

0.792 0.8 0.808 V

REF

Accuracy

C to 70

-1 +

Soft Start

SSC

Charge

Current

= 1.5V

8.0

SSD

Discharge

Current

= 1.5V

1.3

2.7

Under voltage lockout (UVLO)

Upper threshold voltage
(V

)

4.2 V

LWT

Lower threshold voltage
(V

)

4.1 V

Hysteresis

)

O(REF)

= 0.1mA

= 25�C

200 mV

Note 1. Specification refers to Typical Application Circuit.
Note 2. This device is ESD sensitive. Use of standard ESD handling precautions is required.

AP2003

Synchronous PWM Controller

(Preliminary)

Anachip Corp.
www.anachip.com.tw Rev. 0.1 Feb.10, 2004

4/6

Typical Application Circuit

(1)

Option

VCC

COMP

SS/SHDN

SENSE

DRVH

BSTH

GND

DRVL

Q1
STP40NE

Q2
STP40NE

4uH

C9
180/4V

C10
180/4V

C11
180/4V

C12
180/4V

C13
180/4V

Vout=2.0V*

Vin
5V

C8
680/6.3V

C7
680/6.3V

C6
680/6.3V

R7
127

R8
191*

Note:
* Vout=0.8 x (1+R8/R7)

+12V

AP2003

C5
10u

C2
0.1u

R6 Option

R5 Option

(2)

Option

VCC

COMP

SS/SHDN

SENSE

DRVH

BSTH

GND

DRVL

Q1
STP40NE

Q2
STP40NE

4uH

C9
180/4V

C10
180/4V

C11
180/4V

C12
180/4V

C13
180/4V

Vout=2.0V*

Vin
5V

C8
680/6.3V

C7
680/6.3V

C6
680/6.3V

R7
127

R8
191*

Note:
* Vout=0.8 x (1+R8/R7)

AP2003

C5
10u

C2
0.1u

R5 Option

C1
1u

5V input with Bootstrapped BSTH

R6 Option

AP2003

Synchronous PWM Controller

(Preliminary)

Anachip Corp.
www.anachip.com.tw Rev. 0.1 Feb.10, 2004

5/6

Function Description

Synchronous Buck Converter
Primary V

CORE

power is provided by a synchronous,

voltage-mode pulse width modulated (PWM)
controller. This section has all the features required
to build a high efficiency synchronous buck
converter, shutdown function.
The output voltage of the synchronous converter is
set and controlled by the output of the error
amplifier. The external resistive divider reference
voltage is derived from an internal trimmed
band-gap voltage reference. The inverting input of
the error amplifier receives its voltage from the
SENSE pin.

The internal oscillator uses an on-chip capacitor
and trimmed precision current sources to set the
oscillation frequency to 200KHz. The triangular
output of the oscillator sets the reference voltage at
the inverting input of the comparator. When the
oscillator output voltage drops below the error
amplifier output voltage, the comparator output
goes high. This pulls DRVL low, turning off the
low-side FET, and DRVH is pulled high, turning on
the high-side FET (once the cross-current control
allows it). When the oscillator voltage rises back
above the error amplifier output voltage, the
comparator output goes low. This pulls DRVH low,
turning off the high-side FET, and DRVL is pulled
high, turning on the low-side FET (once the
cross-current control allows it).
As SENSE increases, the output voltage of the
error amplifier decreases. This causes a reduction
in the on-time of the high-side MOSFET connected
to DRVH, hence lowering the output voltage.

Under Voltage Lockout
The under voltage lockout circuit of the AP2003
assures that the high-side MOSFET driver outputs
remain in the off state whenever the supply voltage
drops below set parameters. Lockout occurs if V

falls below 4.1V. Normal operation resumes once
V

rises above 4.2V.

Soft Start
Initially, SS/

SHDN

sources 10uA of current to

charge an external capacitor. The outputs of the

error amplifiers are clamped to a voltage
proportional to the voltage on SS/

SHDN

. This

limits the on-time of the high-side MOSFETs, thus
leading to a controlled ramp-up of the output
voltages.

Hiccup Mode
During power up, the SS/

SHDN

pin is internally

pulled low until V

reaches the under-voltage

lockout level of 4.2V. Once V

has reached 4.2V,

the SS/

SHDN

pin is released and begins to source

10uA of current to the external soft-start capacitor.
As the soft-start voltage rises, the output of the
internal error amplifier is clamped to this voltage.
When the error signal reaches the level of the
internal triangular oscillator, which swings from 1V
to 2V at a fixed frequency of 200KHz, switching
occurs. As the error signal crosses over the
oscillator signal, the duty cycle of the PWM signal
continues to increase until the output comes into
regulation.

The soft-start voltage will begin to decrease as the
2uA of current discharge the external capacitor.
When the soft-start voltage reaches 0.8V, the
SS/

SHDN

pin will begin to source 10uA and begin

to charge the external capacitor causing the
soft-start voltage to rise again. Again, when the
soft-start voltage reaches the level of the internal
oscillator, switching will occur.

In conclusion, above is shown a typical "12V
Application Circuit" which has a BSTH voltage
derived by bootstrapping input voltage to the
PHASE node through diode D2. This circuit is very
useful in cases where only single input power of
5V(or 12V) is available.

In order to prevent substrate glitching, a
small-signal diode should be placed in close
proximity to the chip with cathode connected to
PHASE and anode connected to GND.

Электронный компонент: AP2003SLA