AS2842 Datasheet, PDF (1/20 Pages) List of Unclassifed Manufacturers – Current Mode Controller

AS2842/3/4/5
Current Mode Controller
Features
• ^{2.5 V bandgap reference}
trimmed to 1.0% and
temperature-compensated
• ^{Extended temperature range}
from - 40 to 105° C
• ^{AS2842/3 oscillations trimmed}
for precision duty cycle clamp
• ^{AS2844/5 have exact 50% max}
duty cycle clamp
• ^{Advanced oscillator design}
simplifies synchronization
• ^{Improved specs on UVLO}
and hysteresis provide
more predictable start-up
and shutdown
• ^{Improved 5 V regulator provides}
better AC noise immunity
• ^{Guaranteed performance}
with current sense pulled
below ground
• ^{Over-temperature shutdown}
Description
The AS2842 family of control ICs provide pin-for-pin replace-
ment of the industry standard UC3842 series of devices. The
devices are redesigned to provide significantly improved
tolerances in power supply manufacturing. The 2.5 V refer-
ence has been trimmed to 1.0% tolerance. The oscillator
discharge current is trimmed to provide guaranteed duty
cycle clamping rather than specified discharge current. The
circuit is more completely specified to guarantee all param-
eters impacting power supply manufacturing tolerances.
In addition, the oscillator and flip-flop sections have been
enhanced to provide additional performance. The R_T/C_T pin
now doubles as a synchronization input that can be easily
driven from open collector/open drain logic outputs. This
sync input is a high impedance input and can easily be used
for externally clocked systems. The new flip-flop topology
allows the duty cycle on the AS2844/5 to be guaranteed
between 49 and 50%. The AS2843/5 requires less than
0.5 mA of start-up current over the full temperature range.
Ordering Information
Description
8-Pin Plastic DIP
8-Pin Plastic SOIC
Temperature Range
-40 to 105° C
-40 to 105° C
Order Codes
AS2842/3/4/5N
AS2842/3/4/5D-8
Pin Configuration — Top view
PDIP (N)
COMP 1
V_FB 2
I_SENSE 3
R_T/C_T 4
8 V_REG
7 V_CC
6 OUT
5 GND
8L SOIC (D)
COMP 1
V_FB 2
I_SENSE 3
R_T/C_T 4
8 V_REG
7 V_CC
6 OUT
5 GND
ASTEC Semiconductor
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