C2471
Datasheet
RDFC Controllers for Offline Applications up to 6 W
Product data
Page 2 of 18
DS-1639-0805
© Cambridge Semiconductor Ltd 2008
02-May-2008
PIN DEFINITIONS
Figure 2: C2471 Pin Assignment
(drawings are not to scale)
VDD Pin
The VDD pin supplies power to the controller and is maintained at the correct voltage (nominally 3.3 V) by an
internal shunt regulator.
COL Pin
The COL pin is used to sense the collector voltage of the primary switching transistor, via a coupling
capacitor, to control the timing and current levels of the signals produced on the BAS pin.
CS Pin
The CS pin senses the primary switch current via the current sensing resistor. The voltage sensed on this
pin is used to control the operating modes to manage standby and overload protection. Operating
characteristics are programmed via two external resistors.
AUX Pin
The AUX pin provides the supply current for the internal base driver block. The AUX pin is connected to the
external supply rail via a current-limiting resistor to set the maximum base current.
BAS Pin
The BAS pin switches the external bipolar primary switch transistor on and off. The current supplied to the
switch transistor is controlled to minimize the switching losses and thereby help optimize overall system
efficiency.
GND Pin
GND pins provide the ground reference. Where the device has multiple GND pins, all must be connected to
a common, low impedance path.
1
2
3
4
8
7
6
5
1
2
3
6
5
4
BAS
GND
COL
AUX
VDD
CS
GND
NC
NC
BAS
COL
CS
VDD
AUX
C2471LX2
SOT23-6
C2471LW1
PDIP-8
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