CAT37TDI-TE7 CATALYST SEMICONDUCTOR, CAT37TDI-TE7 Datasheet - Page 6

• Manufacturer Part Number: CAT37TDI-TE7
• Description: IC, WHITE LED DRIVER, BOOST, TSOT-23-5
• Manufacturer: CATALYST SEMICONDUCTOR

Specifications of CAT37TDI-TE7

• Led Driver Application: Color LCD And Keypad Backlighting, Digital Cameras
• No. Of Outputs: 1
• Output Current: 20mA
• Output Voltage: 20V
• Input Voltage: 2.5V To 7V
• Topology: Boost
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Operation
frequency, current regulating boost driver for white LEDs.
compensated loop for the regulation of the current in the
LEDs.
diagram. The FB pin is regulated at 95 mV and the current
through the external resistor will set the regulated current in
the LEDs at:
Block Diagram
The CAT37 device is a high efficiency, constant
The device includes a switch and an internally
Operation can be best understood by examining the block
VIN
C1
4
I
LED
CAT37
Over Voltage
VIN
SHDN
+ 0.095
Protection
5
(22 V)
R1
L1
2
GND
Figure 13. CAT37 Block Diagram
1
SW
http://onsemi.com
Current
Sense
Amp
+
−
6
Oscillator
1.2 MHz
& Logic
PWM
boost converter automatically adjusts the FB pin voltage to
be as low as possible. A low FB pin voltage ensures high
efficiency.
monitored cycle−by−cycle. If the current limit is exceeded,
the switch is immediately turned off, protecting the device,
for the remainder of the cycle.
the SHDN pin or by pulling the FB pin higher than 95 mV.
While maintaining LED current regulation, the CAT37
Current through the internal power switch is continuously
PWM dimming operation can be achieved by switching
D1
Error
Amp
90 kW
−
+
0.095 V
REF
6 kW
FB
3
R1
I
LED
C2