LT1932 FCI | Alldatasheet

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Technical content

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. FEATURES APPLICATIONS

  • 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 VIN > VOUT
  • Operates with VIN as Low as 1V
  • Low Profile (1mm) Thin SOT Package
  • Cellular Telephones
  • Handheld Computers
  • Digital Cameras
  • Portable MP3 Players
  • Pagers SOT – 23-6L LT1932 Plastic IZ1932 Chip TJMAX = 125 °C, θJA = 250 °C/W Constant-Current DC/DC LED Driver LT1932

(Note 1) VIN Voltage 10V SHDN Voltage 10V SW Voltage 36V LED Voltage 36V RSET Voltage 1V Junction Temperature 125 °C Operating Temperature Range -10 °C to 85°C Storage Temperature Range: -65°C to 150°C Lead Temperature (Soldering, 10 sec) 300 °C

Electrical Characteristics

The • denotes specifications that apply over the full operating temperature range otherwise specifications are at T A = 25°C. VIN = 1.2V, VSHDN = 1.2V, unless otherwise noted. Parameter Conditions Min Typ Max Unit Minimum Input Voltage 1 V Quiescent Current V RSET = 0.2V V SHDN = 0V 1.2 0.1 1.6 1.0 mA µA RSET Pin Voltage R SET = 1.50k 100 mV LED Pin Voltage R SET = 1.50k, VIN < VOUT (Figure 1) 120 180 mV LED Pin Current RSET = 562Ω, VIN = 1.5V RSET = 750Ω, VIN = 1.2V RSET = 1.50k, VIN = 1.2V RSET = 4.53k, VIN = 1.2V 12.5 17.5 mA mA mA mA LED Pin Current Temperature Coefficient ILED = 15mA -0.02 mA / °C Switching Frequency V IN = 1V 0.8 1.2 1.6 MHz Maximum Switch Duty Cycle • 90 95 % Switch Current Limit 400 550 780 mA Switch VCESAT I SW = 300mA 150 200 mV SHDN Pin Current V SHDN = 0V V SHDN = 2V 0.1 µA µA Start-Up Threshold (SHDN Pin) Shutdown Threshold (SHDN Pin) 0.85 0.25 V V Switch Leakage Current Switch Off, V SW = 5V 0.01 5 µA Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Constant-Current DC/DC LED Driver LT1932

Σ

1.2 MHz

Q S R

5 SHDN

0.04Ω RSET RSET ISET VOUT LED ILED GND 6 161 1163 11641162 Constant-Current DC/DC LED Driver LT1932

Single Cell Driver for One White LED Single Cell Driver for Two White LEDs VIN 1V to 1.5V 4.7 µH D1 VIN SW 5 3 4224.9k RSET 1.50k 2.5V PWM DIMMING CONTROL 4.7µF SHDN RSET GND LED C2 2.2µF15mA VIN 1V to 1.5V 4.7 µH D1 VIN SW 5 3 4224.9k RSET 1.50k 2.5V PWM DIMMING CONTROL 4.7µF SHDN RSET GND LED C2 4.7µF15mA Constant-Current DC/DC LED Driver LT1932

2 - Cell Driver for Two White LEDs 2 - Cell Driver for Three White LEDs VIN 1.8V to 3V 4.7 µH D1 VIN SW 5 3 4260.4k RSET 1.50k 2.5V DC DIMMING CONTROL 4.7µF SHDN RSET GND LED C2 2.2µF15mA VIN 1.8V to 3V 4.7 µH D1 VIN SW 5 3 4260.4k RSET 1.50k 2.5V DC DIMMING CONTROL 4.7µF SHDN RSET GND LED C2 2.2µF15mA Constant-Current DC/DC LED Driver LT1932

2 - Cell Driver for Four White LEDs 2 - Cell Driver for Five White LEDs VIN 1.8V to 3V 4.7 µH D1 VIN SW 5 3 RSET 1.50k 4.7µF SHDN RSET GND LED C2 1µ F15mA PWM DIMMING CONTROL VIN 1.8V to 3V 4.7 µH D1 VIN SW 5 3 RSET 1.50k 4.7µF SHDN RSET GND LED C2 1µ F15mA PWM DIMMING CONTROL Constant-Current DC/DC LED Driver LT1932

Li - lon Driver for Two White LEDs Li - lon Driver for Three White LEDs VIN 2.7V to 4.2V 6.8 µH D1 VIN SW 5 3 4231.6k RSET 1.50k 3.3V PWM DIMMING CONTROL 4.7µF SHDN RSET GND LED C2 2.2µF15mA VIN 2.7V to 4.2V 6.8 µH D1 VIN SW 5 3 4231.6k RSET 1.50k 3.3V PWM DIMMING CONTROL 4.7µF SHDN RSET GND LED C2 2.2µF15mA Constant-Current DC/DC LED Driver LT1932

Li - lon Driver for Four White LEDs Li - lon Driver for Five White LEDs VIN 2.7V to 4.2V 6.8 µH D1 VIN SW 5 3 RSET 1.50k 4.7µF SHDN RSET GND LED C2 1µ F15mA PWM DIMMING CONTROL VIN 2.7V to 4.2V 4.7 µH D1 VIN SW 5 3 RSET 1.50k 4.7µF SHDN RSET GND LED C2 1µ F15mA PWM DIMMING CONTROL Constant-Current DC/DC LED Driver LT1932

Li - lon Driver for Eight White LEDs Li - lon Driver for Ten White LEDs VIN 2.7V to 4.2V 10 µH D1 VIN SW 5 3 RSET 750Ω 4.7µF SHDN RSET GND LED 4.7µF 30mA 100Ω100Ω VIN 3V to 4.2V 4.7 µH D1 VIN SW 5 3 4280.6k RSET 1.50k 3.3V DC DIMMING CONTROL 4.7µF SHDN RSET GND LED C2 1µ F 15mA Constant-Current DC/DC LED Driver LT1932

Li - lon Driver for Six White LEDs VIN 2.7V to 4.2V 4.7 µH D1 VIN SW 5 3 4280.6k RSET 1.50k 3.3V DC DIMMING CONTROL 4.7µF SHDN RSET GND LED C2 1µF 15mA Constant-Current DC/DC LED Driver LT1932

Constant-Current DC/DC LED Driver LT1932

Y X Pads location of LT1932 Die size Хr = 1120 mkm, Уr = 1650 mkm (pad size 100 х 100 mkm2 measured by layer “passivation”) Coordinates of pad No of pad (by layer “passivation”) X mkm (left bottom) Y mkm (left bottom) 1 467 905 2 110 407 3 432 123 4 1104 130 5 1454 163 6 1454 772 7 1151 897 Constant-Current DC/DC LED Driver LT1932