Datasheet LT3800 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | High-Voltage Synchronous Current Mode Step-Down Controller |
| Pages / Page | 24 / 1 — FEATURES. DESCRIPTION. Wide 4V to 60V Input Voltage Range. Output … |
| File Format / Size | PDF / 265 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Wide 4V to 60V Input Voltage Range. Output Voltages up to 36V
Model Line for this Datasheet
Text Version of Document
LT3800 High-Voltage Synchronous Current Mode Step-Down Controller
FEATURES DESCRIPTION
n
Wide 4V to 60V Input Voltage Range
The LT®3800 is a 200kHz fi xed frequency high voltage n
Output Voltages up to 36V
synchronous current mode step-down switching regulator n
Adaptive Nonoverlap Circuitry Prevents Switch
controller. The IC drives standard gate N-channel power
Shoot-Through
MOSFETs and can operate with input voltages from 4V to n
Reverse Inductor Current Inhibit for Discontinuous
60V. An onboard regulator provides IC power directly from
Operation Improves Effi ciency with Light Loads
VIN and provides for output-derived power to minimize n
Output Slew Rate Controlled Soft-Start with
VIN quiescent current. MOSFET drivers employ an internal
Auto-Reset
dynamic bootstrap feature, maximizing gate-source “ON” n 100μA No Load Quiescent Current voltages during normal operation for improved operating n Low 10μA Current Shutdown effi ciencies. The LT3800 incorporates Burst Mode® opera- n 1% Regulation Accuracy tion, which reduces no load quiescent current to under n 200kHz Operating Frequency 100μA. Light load effi ciencies are also improved through n Standard Gate N-Channel Power MOSFETs a reverse inductor current inhibit, allowing the controller n Current Limit Unaffected by Duty Cycle to support discontinuous operation. Both Burst Mode n Reverse Overcurrent Protection operation and the reverse-current inhibit features can be n 16-Lead Thermally Enhanced TSSOP Package disabled if desired. The LT3800 incorporates a program- mable soft-start that directly controls the voltage slew rate
APPLICATIONS
of the converter output for reduced startup surge currents and overshoot errors. The LT3800 is available in a 16-lead n 12V and 42V Automotive and Heavy Equipment thermally enhanced TSSOP package. n 48V Telecom Power Supplies n L Avionics and Industrial Control Systems , LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks and No RSENSE and ThinSOT are trademarks of Linear Technology Corporation. All other n Distributed Power Converters trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 6611131, 6304066, 6498466, 6580258.
TYPICAL APPLICATION 12V 75W DC/DC Converter with Reverse Current Inhibit and Input UVLO
VIN
Effi ciency and Power Loss
20V TO 55V + 1μF 56μF 100 6 ×3 ×2 V V IN BOOST IN = 24V 1μF 95 VIN = 36V 5 1M TG Si7850DP LT3800 82.5k VIN = 60V POWER LOSS (W) 90 4 SHDN SW 1.5nF 200k BAS19 VIN = 48V C 85 3 SS 15μH 174k 1N4148 BURST_EN 20k VCC EFFICIENCY (%) 1% 80 2 1% 1μF LOSS (48V) VFB BG Si7370DP B160 75 1 VC PGND 100pF 82.5k 70 0 SENSE– SENSE+ 0.1 1 10 SGND 680pF ILOAD (A) 0.015Ω 3800 TA01b VOUT 12V AT 75W + 10μF 270μF 3800 TA01a 3800fc 1 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS FUNCTIONAL DIAGRAM APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
FEATURES DESCRIPTION
n
Wide 4V to 60V Input Voltage Range
The LT®3800 is a 200kHz fi xed frequency high voltage n
Output Voltages up to 36V
synchronous current mode step-down switching regulator n
Adaptive Nonoverlap Circuitry Prevents Switch
controller. The IC drives standard gate N-channel power
Shoot-Through
MOSFETs and can operate with input voltages from 4V to n
Reverse Inductor Current Inhibit for Discontinuous
60V. An onboard regulator provides IC power directly from
Operation Improves Effi ciency with Light Loads
VIN and provides for output-derived power to minimize n
Output Slew Rate Controlled Soft-Start with
VIN quiescent current. MOSFET drivers employ an internal
Auto-Reset
dynamic bootstrap feature, maximizing gate-source “ON” n 100μA No Load Quiescent Current voltages during normal operation for improved operating n Low 10μA Current Shutdown effi ciencies. The LT3800 incorporates Burst Mode® opera- n 1% Regulation Accuracy tion, which reduces no load quiescent current to under n 200kHz Operating Frequency 100μA. Light load effi ciencies are also improved through n Standard Gate N-Channel Power MOSFETs a reverse inductor current inhibit, allowing the controller n Current Limit Unaffected by Duty Cycle to support discontinuous operation. Both Burst Mode n Reverse Overcurrent Protection operation and the reverse-current inhibit features can be n 16-Lead Thermally Enhanced TSSOP Package disabled if desired. The LT3800 incorporates a program- mable soft-start that directly controls the voltage slew rate
APPLICATIONS
of the converter output for reduced startup surge currents and overshoot errors. The LT3800 is available in a 16-lead n 12V and 42V Automotive and Heavy Equipment thermally enhanced TSSOP package. n 48V Telecom Power Supplies n L Avionics and Industrial Control Systems , LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks and No RSENSE and ThinSOT are trademarks of Linear Technology Corporation. All other n Distributed Power Converters trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 6611131, 6304066, 6498466, 6580258.
TYPICAL APPLICATION 12V 75W DC/DC Converter with Reverse Current Inhibit and Input UVLO
VIN
Effi ciency and Power Loss
20V TO 55V + 1μF 56μF 100 6 ×3 ×2 V V IN BOOST IN = 24V 1μF 95 VIN = 36V 5 1M TG Si7850DP LT3800 82.5k VIN = 60V POWER LOSS (W) 90 4 SHDN SW 1.5nF 200k BAS19 VIN = 48V C 85 3 SS 15μH 174k 1N4148 BURST_EN 20k VCC EFFICIENCY (%) 1% 80 2 1% 1μF LOSS (48V) VFB BG Si7370DP B160 75 1 VC PGND 100pF 82.5k 70 0 SENSE– SENSE+ 0.1 1 10 SGND 680pF ILOAD (A) 0.015Ω 3800 TA01b VOUT 12V AT 75W + 10μF 270μF 3800 TA01a 3800fc 1 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS FUNCTIONAL DIAGRAM APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
