AS2208 Datasheet, PDF (1/6 Pages) List of Unclassifed Manufacturers – Primary Side PWM Controller

AS2208
Primary Side PWM Controller
Preliminary Specification
Features
• ^{Low Startup Current}
• ^{Single-start or auto-restart}
modes
• ^{Oscillator trimmed for precision}
duty cycle clamp
• ^{Standard temperature range}
extended to 105°C
• ^{Remote on / off control}
• ^{Self limiting supply Voltage}
• ^{Standard current mode control}
Description
The AS2208 is a simplified pulse width modulation control-
ler, offering similar functionality as that of the AS3842.
Based on the AS2214, the AS2208 provides the additional
features of low startup current and overvoltage latching,
making it a good solution for adapter applications.
The PWM function is controlled by the current sense com-
parator for normal current mode control. The COMP pin,
which serves as an input to the current sense comparator,
provides a 1 mA current source which can be tied directly to
the control loop optocoupler. The output stage is a high
current totem pole output that sees only 85 ns delay from the
PWM comparator.
The AS2208 requires only 100 µA of startup current. The
undervoltage lockout (UVLO) thresholds are nominally 14V
for turn on and 8 V for turn off. The VREG pin, based on a
trimmed bandgap reference, provides a temperature com-
pensated 5 V to loads of up to 50 mA. The oscillator
discharge current is trimmed to provide guaranteed duty
cycle clamping.
Pin Configuration — Top view
PDIP (N)
COMP 1
ISNS 2
RT/CT 3
OV 4
8 ^VREG
7 VCC
6 OUT
5 GND
8L SOIC (D)
COMP 1
ISNS 2
RT/CT 3
OV 4
8 ^VREG
7 VCC
6 OUT
5 GND
Ordering Information
Package
8-Pin Plastic DIP
8-Pin Plastic SOIC
ASTEC Semiconductor
Temperature Range
0 to 105° C
0 to 105° C
77
Order Code
AS2208N
AS2208D