Preliminary Datasheet
CURRENT MODE PWM CONTROLLER
AZ3842B/3B/4B/5B
General Description
Features
The AZ3842B/3B/4B/5B are high performance fixed
frequency current-mode PWM controller series. The
difference between AZ384XA and AZ384XB is that
they have different start-up currents.
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Start-up Current: 0.30mA for AZ3842B/44B
0.20mA for AZ3843B/45B
Robust V
Line/Load Regulation
REF
Low Line Regulation : 4mV
Low Load Regulation : 4mV
High Stability of Reference Voltage over a Full
These integrated circuits are optimized for off-line and
DC-DC converter applications with minimum external
components. They feature under-voltage lockout
(UVLO) circuit with low start-up current, trimmed
oscillator for precise duty cycle control, current sense
comparator providing maximum current limiting and a
totem pole output stage for increasing output current.
In addition, these ICs also feature accurate protection
against over-temperature, over-current and maximal
output power.
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o
Temperature Range: 0.2mV/ C
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Operating Frequency up to 500KHz
High PWM Frequency Stability over a Full Tem-
perature Range: 2.5%
High PWM Frequency Stability under a Full Sup-
ply Voltage Range: 0.2%
Accurate Over-temperature Protection with Hys-
teresis
UVLO with Hysteresis
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The AZ3842B and AZ3844B have UVLO thresholds
of 16V(on) and 10V(off); The corresponding thresh-
olds for AZ3843B and AZ3845B are 8.4 V(on) and
7.6V(off).
Applications
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Off-line Converter
DC-DC Converter
Voltage Adapter
CRT Monitor Power Supply
Desktop Power Supply
DVD/STB Power Supply
The AZ3842B and AZ3843B can operate approaching
100% duty cycle; AZ3844B and AZ3845B can operate
from zero to 50% duty cycle.
These ICs are available in 3 packages: SOIC-8, DIP-8
and SOIC-14.
SOIC-14
SOIC-8
DIP-8
Figure 1. Package Types of AZ3842B/3B/4B/5B
BCD Semiconductor Manufacturing Limited
Apr. 2005 Rev. 1. 2
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