Data Sheet
PULSE-WIDTH-MODULATION CONTROL CIRCUITS AZ494A/C
General Description Features
The AZ494A/C is a voltage mode pulse width modula-
Stable 4.95V/5V Reference Voltage Trimmed to
tion switching regulator control circuit designed pri-
1.0% Accuracy
marily for power supply control.
Uncommitted Output TR for 200mA Sink or
Source Current
The AZ494A/C consists of a reference voltage circuit,
Single-End or Push-Pull Operation Selected by
two error amplifiers, an on-chip adjustable oscillator, a
Output Control
dead-time control (DTC) comparator, a pulse-steering
Internal Circuitry Prohibits Double Pulse at Either
control flip-flop, and an output control circuit. The pre-
Output
cision of voltage reference (V ) is improved up to
REF
Complete PWM Control Circuit with Variable
1% through trimming and this provides a better output
Duty Cycle
voltage regulation. The AZ494A/C provides for push-
On-Chip Oscillator with Master or Slave Opera-
pull or single-ended output operation, which can be
tion
selected through the output control.
Applications
The difference between AZ494A and AZ494C is that
they have 4.95V and 5V reference voltage respectively.
SMPS
The AZ494A/C is available in standard packages of
Back Light Inverter
DIP-16 and SOIC-16.
Charger
DIP-16
SOIC-16
Figure 1. Package Types of AZ494A/C
Sep. 2009 Rev. 1. 4 BCD Semiconductor Manufacturing Limited
1 Data Sheet
PULSE-WIDTH-MODULATION CONTROL CIRCUITS AZ494A/C
Pin Configuration
M/P Package
(SOIC-16/DIP-16)
1IN + 2IN +
1
16
1IN - 15 2IN -
2
3
FEEDBACK 14 REF
DTC 4 OUTPUT CTRL
13
5 12
CT V
CC
6
RT 11 C2
7
10
GND E2
C1 8 9 E1
Figure 2. Pin Configuration of AZ494A/C (Top View)
Output Function Control Table
Signal for Output Control Output Function
V = GND Single-ended or parallel output
I
V = V Normal push-pull operation
I REF
Functional Block Diagram
OUTPUT CTRL
6
13 8
RT
C1
5 Oscillator
Pulse-Steering
CT
Flip-Flop
Q1
Dead-Time Control
Comparator
9
E1
D
4 C2
DTC + 11
CK
0.12V
Q2
Error Amplifier 1 +
10
PWM
E2
1
Comparator
1IN + +
2
1IN -
12
V
CC
Error Amplifier 2
16
2IN + + Reference 14
REF
Regulator
15
2IN -
0.7mA
7
GND
3
FEEDBACK
Figure 3. Functional Block Diagram of AZ494A/C
Sep. 2009 Rev. 1. 4 BCD Semiconductor Manufacturing Limited
2