Features: Constant 500kHz Switching Frequency
Easily Synchronizable
Uses All Surface Mount Components
Inductor Size Reduced to 5µH
Saturating Switch Design: 0.4Ω
Effective Supply Current: 2.5mA
Shutdown Current: 20µA
Cycle-by-Cycle Current LimitingApplicationPortable Computers
Battery-Powered Systems
Battery Charger
Distributed PowerSpecificationsLT1375/LT1376........................................................ 25V
LT1375HV/LT1376HV............................................... 30V
BOOST Pin Voltage
LT1375/LT1376........................................................ 35V
LT1375HV/LT1376HV............................................... 40V
SHDN Pin Voltage...................................................... 7V
BIAS Pin Voltage....................................................... 7V
FB Pin Voltage (Adjustable Part)............................ 3.5V
FB Pin Current (Adjustable Part)............................ 1mA
Sense Voltage (Fixed 5V Part).................................. 7V
SYNC Pin Voltage...................................................... 7V
Operating Ambient Temperature Range
LT1375C/LT1376C..................................... 0°C to 70°C
LT1375I/LT1376I................................... 40°C to 85°C
Operating Junction Temperature Range
LT1375C/LT1376C...................................0°C to 125° C
LT1375I/LT1376I................................. 40°C to 125°C
Storage Temperature Range................65°C to 150°C
Lead Temperature (Soldering, 10 sec)................ 300°C
DescriptionThe LT® 1375/LT1376 are 500kHz monolithic buck mode switching regulators. A 1.5A switch is included on the die along with all the necessary oscillator, control and logic circuitry. High switching frequency allows a considerable reduction in the size of external components. The topologyis current mode for fast transient response and good loop stability. Both fixed output voltage and adjustable parts are available.
A special high speed bipolar process and new design techniques achieve high efficiency at high switching fre- quency. Efficiency is maintained over a wide output cur- rent range by using the output to bias the circuitry and by utilizing a supply boost capacitor to saturate the power switch. A shutdown signal will reduce supply current to 20µ A on both parts. The LT1375 can be externally syn- chronized from 550kHz to 1MHz with logic level inputs.
The LT1375/LT1376 fit into standard 8-pin PDIP and SO packages, as well as a fused lead 16-pin SO with much lower thermal resistance. Full cycle-by-cycle short-cir- cuit protection and thermal shutdown are provided. Standard surface mount external parts are used, includ- ing the inductor and capacitors.
For low input voltage applications with 3.3V output, see LT1507. This is a functionally identical part that can operate with input voltages between 4.5V and 12V.
LT1376 Data Sheet
