LT1932 Datasheet, PDF (1/12 Pages) Linear Technology – Constant-Current DC/DC LED Driver in ThinSOT

Constant-Current DC/DC LED Driver LT1932
DESCRIPTION
The LT1932 is a fixed frequency step-up DC/DC converter designed to
operate as a constant-current source. Because it directly regulates
output current, the LT1932 is ideal for driving light emitting diodes (LEDs)
whose light intensity is proportional to the current passing through them,
not the voltage across their terminals.
With an input voltage range of 1V to 10V, the device works from a variety of
input sources. The LT1932 accurately regulates LED current even when
the input voltage is higher than the LED voltage, greatly simplifying
battery- powered designs. A single external resistor sets LED current
between 5mA and 40mA, which can then be easily adjusted using either a
DC voltage or a pulse width modulated (PWM) signal. When the LT1932 is
placed in shutdown, the LEDs are disconnected from the output, ensuring a
quiescent current of under 1µA for the entire circuit. The device’s 1.2MHz
switching frequency permits the use of tiny, low profile chip inductors and
capacitors to minimize footprint and cost in space-conscious portable
applications.
SOT – 23-6L
1
6
3
2
1
LT1932 Plastic
IZ1932 Chip
T_A = -40 ... +85 °C
T_JMAX = 125 °C, θ_JA = 250 °C/W
FEATURES
• Up to 80% Efficiency
• Inherently Matched LED Current
• Adjustable Control of LED Current
• Drives Five White LEDs from 2V
• Drives Six White LEDs from 2.7V
• Drives Eight White LEDs from 3V
• Disconnects LEDs In Shutdown
• 1.2MHz Fixed Frequency Switching
• Uses Tiny Ceramic Capacitors
• Uses Tiny 1mm-Tall Inductors
• Regulates Current Even When V_IN > V_OUT
• Operates with V_IN as Low as 1V
• Low Profile (1mm) Thin SOT Package
APPLICATIONS
• Cellular Telephones
• Handheld Computers
• Digital Cameras
• Portable MP3 Players
• Pagers