LT1247 - 1MHz Off-Line Current Mode PWM and DC/DC Converter
Features
- Current Mode Operation to 1MHz
- 30ns Current Sense Delay
- <250mA Low Start-Up Current
- Current Sense Leading Edge Blanking
- Pin Compatible with UC1842
- Undervoltage Lockout with Hysteresis
- No Cross-Conduction Current
- Trimmed Bandgap Reference
- 1A Totem Pole Output
Typical Application
Description
The LT®1246/LT1247 are 8-pin, fixed frequency, current mode, pulse width modulators. These devices are designed to be improved plug compatible versions of the industry standard UC1842 PWM circuit. The LT1246/ LT1247 are optimized for off-line and DC/DC converter applications. They contain a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output stage ideally suited to driving power MOSFETs. Start-up current has been reduced to less than 250µA. Cross-conduction current spikes in the totem pole output stage have been eliminated, making 1MHz operation practical. Several new features have been incorporated. Leading edge blanking has been added to the current sense comparator. This minimizes or eliminates the filter that is normally required. Eliminating this filter allows the current sense loop to operate with minimum delays. Trims have been added to the oscillator circuit for both frequency and sink current, and both of these parameters are tightly specified. The output stage is clamped to a maximum VOUT of 18V in the on state. The output and the reference output are actively pulled low during under-voltage lockout.Packaging
CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.
For complete and up to date package information and drawings, please refer to our packaging page
| Part Number | Package | Code | Temp | Package Drawing |
RoHS |
|---|---|---|---|---|---|
| LT1247CN8#PBF | N-8 | N | C | 05-08-1510 (N8) | Yes |
| LT1247CS8#PBF | SO-8 | S8 | C | 05-08-1610 (S8) | Yes |
| LT1247CS8#TRPBF | SO-8 | S8 | C | 05-08-1610 (S8) | Yes |
Order Info
- Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
- Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
- Please refer to our general ordering information or the product datasheet for more details
Package Variations and Pricing
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LT1247CN8#PBF | N-8 | C | $2.60 | $2.10 | Yes | |
| LT1247CS8#PBF | SO-8 | C | $2.85 | $2.30 | Yes | |
| LT1247CS8#TRPBF | SO-8 | C | $2.36 | Yes | ||
| Buy Now • Request Samples | ||||||
Demo Boards
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 |
|---|---|---|---|
| DC227A-A | LT1247CS8 LT1431CS8 | 35W, Isolated Forward Converter, Half Brick, 36 to 72Vin, 5V or 3.3Vout @ 7A, 500V DC Isolation | Contact Factory | |
| DC227A-B | LT1247CS8 LT1431CS8 | 35W, Isolated Forward Converter, Half Brick, 36 to 72Vin, 5V or 3.3Vout @ 7A, 1500V DC Isolation | Contact Factory | |
| DC227A-C | LT1247CS8 LT1431CS8 | 35W, Isolated Forward Converter, Half Brick, 36 to 72Vin, 5V or 3.3Vout @ 7A, 500V DC Isolation, High Efficiency | Contact Factory | |
| Buy Now | |||
Applications
- Off-Line Converters
- DC/DC Converters
People Who Viewed This Product Also Viewed
- LT1241 - High Speed Current Mode Pulse Width Modulators
- LT1245 - High Speed Current Mode Pulse Width Modulators
- LTC6992 - TimerBlox: Voltage-Controlled Pulse Width Modulator (PWM)
- LT4320/LT4320-1 - Ideal Diode Bridge Controller
- LT1246 - 1MHz Off-Line Current Mode PWM and DC/DC Converter
- LT1158 - Half Bridge N-Channel Power MOSFET Driver
- LT3080 - Adjustable 1.1A Single Resistor Low Dropout Regulator
- LT8705 - 80V VIN and VOUT Synchronous 4-Switch Buck- Boost DC/DC Controller
- LT3796/LT3796-1 - 100V Constant-Current and Constant-Voltage Controller with Dual Current Sense
- LT1243 - High Speed Current Mode Pulse Width Modulators
Product Notifications
Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.
Forgot your password? Click here.
Need help? Email mylinear@linear.com with questions and comments.
Design Tools
LTspice
LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice
Models for the following parts are available in LTspice:
LT1247
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
