DocumentationDatasheet
Design Note
Reliability Data
LT Journal
cad_symbol
ltspice
Features
- Inherently Matched LED Current
- High Efficiency: 84% Typical
- Drives Up to Four LEDs from a 3.2V Supply
- Drives Up to Six LEDs from a 5V Supply
- 36V Rugged Bipolar Switch
- Fast 1.2MHz Switching Frequency
- Uses Tiny 1mm Tall Inductors
- Requires Only 0.22µF Output Capacitor
- Low Profile SC70 and ThinSOT™ Packaging
Typical Application
Description
The LT1937 is a step-up DC/DC converter specifically designed to drive white LEDs with a constant current. The device can drive two, three or four LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The LT1937 switches at 1.2MHz, allowing the use of tiny external components. The output capacitor can be as small as 0.22µF, saving space and cost versus alternative solutions. A low 95mV feedback voltage minimizes power loss in the current setting resistor for better efficiency.
The LT1937 is available in low profile SC70 and ThinSOT packages.
SC-70,SOT-23
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LT1937ES5#PBF | SOT | 5 | E | $1.86 | |
| LT1937ES5#TRMPBF | SOT | 5 | E | $1.86 | $1.38 |
| LT1937ES5#TRPBF | SOT | 5 | E | $1.86 | $1.36 |
| LT1937ESC6#PBF | SC70 | 6 | E | $2.14 | |
| LT1937ESC6#TRMPBF | SC70 | 6 | E | $2.14 | $1.53 |
| LT1937ESC6#TRPBF | SC70 | 6 | E | $2.14 | $1.51 |
| LT1937ES5 | SOT | 5 | E | $3.72 | |
| LT1937ES5#TR | SOT | 5 | E | $3.72 | $2.72 |
| LT1937ESC6 | SC70 | 6 | E | $4.28 | |
| LT1937ESC6#TR | SC70 | 6 | E | $4.28 | $3.02 |
| LT1937ES5#TRM | SOT | 5 | E | $3.72 | $2.76 |
| LT1937ESC6#TRM | SC70 | 6 | E | $4.28 | $3.06 |
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.
| Part Number | Description | Price | Documentation |
|---|---|---|---|
| DC484A | LT1937ES5 | Single Cell White LED(4) Driver with On-Board Battery, Vin 2.7V - 5V | $75.00 | |
| DC507A | LT1937ESC6 | 2-Ckt, High Efficiency Constant-Current Single Cell Li-Ion White LED (4) Driver with On-Board Battery | $75.00 |