FAN5640S7X Datasheet, PDF (2/11 Pages) Fairchild Semiconductor – FAN5640 Dual High-Side Constant Current Source for High-Voltage Keypad LED Illumination

Block Diagram
OTP
+
CLIM
EN
500k
Reference
+
Control
+
-
1:275 Current
Mirror Ratio
Pin Configuration
GND
RSET
Figure 2. Block Diagram
VIN
IOUT1
IOUT2
Figure 3. Pin Assignments
Pin Definitions
Pin #
1
2
3
4
5
6
Name
IOUT1
GND
RSET
EN
VIN
IOUT2
Description
Output Current 1. The programmed current I_OUT is sourced from this pin. If only one channel is
used, IOUT1 and IOUT2 can be tied together to boost the output current. It can also be left
floating or tied to pin 5.
Ground
RSET. Connect a programming resistor R_EXT to this pin. This pin’s output voltage is 0.475V when
EN is HIGH. The current through the external resistor establishes the current I_OUT, where I_OUT =
275 • [0.475V / R_EXT].
Enable. When HIGH, the IC applies the programmed current I_OUT to both IOUT1 and IOUT2.
When LOW, IC enters Shutdown Mode. If pulsed, this pin modulates the output current. The
minimum pulse width is determined by the speed of the turn-on circuitry. This pin contains an
internal pull-down resistor of 500K.
Input Supply. Apply 6 to 20V at this pin (see Dropout Limitations under the Application
Information section).
Output Current 2. The programmed current I_OUT is sourced from this pin. If only one channel is
used, IOUT1 and IOUT2 can be tied together to boost the output current. It can also be left
floating or tied to pin 5.
© 2006 Fairchild Semiconductor Corporation
FAN5640 • Rev. 1.0.2
2
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