LT1108 - Micropower DC/DC Converter Adjustable and Fixed 5V, 12V
Datasheet 
DocumentationDatasheet
Application Note
- AN51 - Power Conditioning for Notebook and Palmtop Systems
- AN61 - Practical Circuitry for Measurement and Control Problems
Reliability Data
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Features
- Operates at Supply Voltages from 2V to 30V
- Consumes Only 110µA Supply Current
- Works in Step-Up or Step-Down Mode
- Only Four External Components Required
- Low Battery Detector Comparator On-Chip
- User Adjustable Current Limit
- Internal 1A Power Switch
- Fixed or Adjustable Output Voltage Versions
- Space Saving 8-Pin MiniDIP or S8 Package
Typical Application
Description
The LT1108 is a versatile micropower DC/DC converter. The device requires only four external components to deliver a fixed output of 5V or 12V. Supply voltage ranges from 2V to 12V in step-up mode and to 30V in step-down mode.The LT1108 functions equally well in step-up,step-down, or inverting applications.The LT1108 is pin-for-pin compatible with the LT1173,but has a duty cycle of 70%, resulting in increased outputcurrent in many applications. The LT1108 can deliver 150mA at 5V from a 2 AA cell input and 5V at 300mA from 9V in step-down mode. Quiescent current is just 110µA,making the LT1108 ideal for power conscious battery-operated systems.
Switch current limit can be programmed with a single resistor.An auxiliary gain block can be configured as a low battery detector, linear post regulator, under voltage lock-out circuit, or error amplifier.
N-8,SO-8
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LT1108CN8#PBF | PDIP | 8 | C | $3.00 | $2.45 |
| LT1108CN8-12#PBF | PDIP | 8 | C | $3.00 | $2.45 |
| LT1108CN8-5#PBF | PDIP | 8 | C | $3.00 | $2.45 |
| LT1108CS8#PBF | SO | 8 | C | $3.42 | $2.75 |
| LT1108CS8#TRPBF | SO | 8 | C | $2.81 | |
| LT1108CS8-12#PBF | SO | 8 | C | $3.42 | $2.75 |
| LT1108CS8-12#TRPBF | SO | 8 | C | $2.81 | |
| LT1108CS8-5#PBF | SO | 8 | C | $3.42 | $2.75 |
| LT1108CS8-5#TRPBF | SO | 8 | C | $2.81 | |
| LT1108CN8 | PDIP | 8 | C | $6.00 | $4.90 |
| LT1108CN8-12 | PDIP | 8 | C | $6.00 | $4.90 |
| LT1108CN8-5 | PDIP | 8 | C | $6.00 | $4.90 |
| LT1108CS8 | SO | 8 | C | $6.84 | $5.50 |
| LT1108CS8#TR | SO | 8 | C | $5.62 | |
| LT1108CS8-12 | SO | 8 | C | $6.84 | $5.50 |
| LT1108CS8-12#TR | SO | 8 | C | $5.62 | |
| LT1108CS8-5 | SO | 8 | C | $6.84 | $5.50 |
| LT1108CS8-5#TR | SO | 8 | C | $5.62 |
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.