Datasheet LT1375, LT1376 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 1.5A, 500kHz Step-Down Switching Regulators |
| Pages / Page | 28 / 1 — FEATURES. Constant 500kHz Switching Frequency. Uses All Surface Mount … |
| File Format / Size | PDF / 518 Kb |
| Document Language | English |
FEATURES. Constant 500kHz Switching Frequency. Uses All Surface Mount Components. Inductor Size Reduced to 5. APPLICATIO S
Model Line for this Datasheet
- LT1375CN8#PBF LT1375CN8-5#PBF LT1375CS8#PBF LT1375CS8#TRPBF LT1375CS8-5#PBF LT1375CS8-5#TRPBF LT1375HVCS8#PBF LT1375HVCS8#TRPBF LT1375HVIS8#PBF LT1375HVIS8#TRPBF LT1375IN8#PBF LT1375IN8-5#PBF LT1375IS8#PBF LT1375IS8#TRPBF LT1375IS8-5#PBF LT1375IS8-5#TRPBF
- LT1376CN8#PBF LT1376CN8-5#PBF LT1376CS#PBF LT1376CS#TRPBF LT1376CS8#PBF LT1376CS8#TRPBF LT1376CS8-5#PBF LT1376CS8-5#TRPBF LT1376HVCS#PBF LT1376HVCS#TRPBF LT1376HVCS8#PBF LT1376HVCS8#TRPBF LT1376HVIS#PBF LT1376HVIS#TRPBF LT1376HVIS8#PBF LT1376HVIS8#TRPBF LT1376IN8#PBF LT1376IN8-5#PBF LT1376IS#PBF LT1376IS#TRPBF LT1376IS8#PBF LT1376IS8#TRPBF LT1376IS8-5#PBF LT1376IS8-5#TRPBF
Text Version of Document
LT1375/LT1376 1.5A, 500kHz Step-Down Switching Regulators
FEATURES
■
Constant 500kHz Switching Frequency
is current mode for fast transient response and good loop ■
Uses All Surface Mount Components
stability. Both fixed output voltage and adjustable parts are ■
Inductor Size Reduced to 5
µ
H
available. ■ Easily Synchronizable A special high speed bipolar process and new design ■ Saturating Switch Design: 0.4Ω techniques achieve high efficiency at high switching fre- ■ Effective Supply Current: 2.5mA quency. Efficiency is maintained over a wide output cur- ■ Shutdown Current: 20µA rent range by using the output to bias the circuitry and by ■ Cycle-by-Cycle Current Limiting utilizing a supply boost capacitor to saturate the power
U
switch. A shutdown signal will reduce supply current to
APPLICATIO S
20µA on both parts. The LT1375 can be externally syn- chronized from 580kHz to 900kHz with logic level inputs. ■ Portable Computers ■ Battery-Powered Systems The LT1375/LT1376 fit into standard 8-pin PDIP and SO ■ Battery Charger packages, as well as a fused lead 16-pin SO with much ■ Distributed Power lower thermal resistance. Full cycle-by-cycle short-cir-
U
cuit protection and thermal shutdown are provided.
DESCRIPTIO
Standard surface mount external parts are used, includ- ing the inductor and capacitors. The LT®1375/LT1376 are 500kHz monolithic buck mode For low input voltage applications with 3.3V output, see switching regulators. A 1.5A switch is included on the die LT1507. This is a functionally identical part that can along with all the necessary oscillator, control and logic operate with input voltages between 4.5V and 12V. circuitry. High switching frequency allows a considerable , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. reduction in the size of external components. The topology All other trademarks are the property of their respective owners.
U TYPICAL APPLICATIO 5V Buck Converter Efficiency vs Load Current
D2 100 1N914 VOUT = 5V VIN = 10V C2 90 L = 10µH 0.1µF BOOST INPUT OUTPUT** V V IN 6V† TO 25V SW 5V, 1.25A 80 C3* L1** + LT1376-5 BIAS 10µF TO 5µH 50µF DEFAULT SHDN FB = ON 70 GND VC C1 + EFFICIENCY (%) D2 100µF, 10V CC 1N5818 SOLID 3.3nF 60 TANTALUM 50 * RIPPLE CURRENT ≥ IOUT/2 0 0.25 0.50 0.75 1.00 1.25 ** INCREASE L1 TO 10µH FOR LOAD CURRENTS ABOVE 0.6A AND TO 20µH ABOVE 1A † LOAD CURRENT (A) FOR INPUT VOLTAGE BELOW 7.5V, SOME RESTRICTIONS MAY APPLY. SEE APPLICATIONS INFORMATION. 1375/76 TA01 1375/76 TA02 13756fd 1
FEATURES
■
Constant 500kHz Switching Frequency
is current mode for fast transient response and good loop ■
Uses All Surface Mount Components
stability. Both fixed output voltage and adjustable parts are ■
Inductor Size Reduced to 5
µ
H
available. ■ Easily Synchronizable A special high speed bipolar process and new design ■ Saturating Switch Design: 0.4Ω techniques achieve high efficiency at high switching fre- ■ Effective Supply Current: 2.5mA quency. Efficiency is maintained over a wide output cur- ■ Shutdown Current: 20µA rent range by using the output to bias the circuitry and by ■ Cycle-by-Cycle Current Limiting utilizing a supply boost capacitor to saturate the power
U
switch. A shutdown signal will reduce supply current to
APPLICATIO S
20µA on both parts. The LT1375 can be externally syn- chronized from 580kHz to 900kHz with logic level inputs. ■ Portable Computers ■ Battery-Powered Systems The LT1375/LT1376 fit into standard 8-pin PDIP and SO ■ Battery Charger packages, as well as a fused lead 16-pin SO with much ■ Distributed Power lower thermal resistance. Full cycle-by-cycle short-cir-
U
cuit protection and thermal shutdown are provided.
DESCRIPTIO
Standard surface mount external parts are used, includ- ing the inductor and capacitors. The LT®1375/LT1376 are 500kHz monolithic buck mode For low input voltage applications with 3.3V output, see switching regulators. A 1.5A switch is included on the die LT1507. This is a functionally identical part that can along with all the necessary oscillator, control and logic operate with input voltages between 4.5V and 12V. circuitry. High switching frequency allows a considerable , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. reduction in the size of external components. The topology All other trademarks are the property of their respective owners.
U TYPICAL APPLICATIO 5V Buck Converter Efficiency vs Load Current
D2 100 1N914 VOUT = 5V VIN = 10V C2 90 L = 10µH 0.1µF BOOST INPUT OUTPUT** V V IN 6V† TO 25V SW 5V, 1.25A 80 C3* L1** + LT1376-5 BIAS 10µF TO 5µH 50µF DEFAULT SHDN FB = ON 70 GND VC C1 + EFFICIENCY (%) D2 100µF, 10V CC 1N5818 SOLID 3.3nF 60 TANTALUM 50 * RIPPLE CURRENT ≥ IOUT/2 0 0.25 0.50 0.75 1.00 1.25 ** INCREASE L1 TO 10µH FOR LOAD CURRENTS ABOVE 0.6A AND TO 20µH ABOVE 1A † LOAD CURRENT (A) FOR INPUT VOLTAGE BELOW 7.5V, SOME RESTRICTIONS MAY APPLY. SEE APPLICATIONS INFORMATION. 1375/76 TA01 1375/76 TA02 13756fd 1
