IS31BL3508A
Integrated Silicon Solution, Inc. – www.issi.com
Rev. A, 05/10/2013
1
1.0MHZ BOOST CONVERTER WITH 38V INTERNAL MOSFET SWITCH
May 2013
GENERAL DESCRIPTION
IS31BL3508A is a boost converter featuring an
integrated MOSFET switch designed for driving series
strings of LED or other device. Input operating voltage
range is 2.7V~5.5V. The device regulates the LED load
current is set using an external, low value sensing
resistor. The device adjusts the PWM duty cycle of the
switch to maintain the voltage at the FB pin at a value
of 0.3V.
The IS31BL3508A operates at a constant switching
frequency of 1.0MHz to allow for small component size.
IS31BL3508A features an over voltage shutdown pin
which prevents the output voltage from exceeding 38V
(typ.) in the case of an open circuit condition.
The device is offered in a TSOT-23-6 and SOT-23-6
package and a temperature rating from -40°C ~ +85°C.
FEATURES
Supply voltage: 2.7V~5.5V
Built-in soft start
Drive series strings of 10 LEDs or 3×8 LEDs
PWM or DC voltage dimming
Frequency of PWM is 500Hz ~ 500kHz
1.0MHz high speed switching frequency
0.3V feedback voltage
Integrated high power MOSFET
Over voltage protection
-40°C ~ +85°C working temperature range
TSOT-23-6 and SOT-23-6 package
APPLICATIONS
Small LCD Backlights
Notebook PC
GPS
TYPICAL APPLICATION CIRCUIT
Figure 1 Constant current white LED driver using PWM at the EN pin to control intensity
Note 1: C
OUT
must be rated for 50V. Smaller values of output capacitance will cause the LED current ripple to increase.
Note 2: The resistor R
EST
should be placed as close as possible to the FB pin to prevent the EMI.
Note 3: D
1
must choose 60V and peak current is determined by the load. Please refer to Page 9 for detail information.
