CAT4101TV-T75 Datasheet, PDF (7/11 Pages) ON Semiconductor – 1 A Constant-Current LED Driver with PWM Dimming

BLOCK DIAGRAM
VIN
LED
VIN
Undervoltage & Thermal
Lockout
EN/PWM
Shutdown Delay
CAT4101
RSET
Reference Voltage
RSET Regulator & Mirror
Current
Regulator
GND
Figure 2. CAT4101 Functional Block Diagram
BASIC OPERATION
The CAT4101 has one highly accurate LED current
sink to regulate LED current in a string of LEDs. The
LED current is mirrored from the current flowing from
the RSET pin according to the following formula:
I_LED
≅
400 ×
1.2 V
R _SET
The LED channel needs a minimum of 500 mV
headroom to sink constant regulated current. If the
input supply falls below 2 V, the under-voltage
lockout circuit disables the LED channel.
For applications requiring current higher than 1 A,
several CAT4101 devices can be connected in
parallel.
The LED channel can withstand and operate at
voltages up to 25 V. This makes the device ideal for
driving long strings of high power LEDs from a high
voltage source.
Table 1. RSET Resistor Settings
LED Current [mA]
100
350
700
1000
RSET [Ω]
4870
1470
750
549
© 2009 SCILLC. All rights reserved.
7
Characteristics subject to change without notice
Doc. No. MD-5036, Rev. D