Datasheet LTC7851, LTC7851-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Quad Output, Multiphase Step-Down Voltage Mode DC/DC Controller with Accurate Current Sharing |
| Pages / Page | 38 / 1 — FEATURES. DESCRIPTION. Operates with Power Blocks, DrMOS or External. … |
| Revision | A |
| File Format / Size | PDF / 4.2 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Operates with Power Blocks, DrMOS or External. Gate Drivers and MOSFETs
Model Line for this Datasheet
Text Version of Document
LTC7851/LTC7851-1 Quad Output, Multiphase Step-Down Voltage Mode DC/DC Controller with Accurate Current Sharing
FEATURES DESCRIPTION
n
Operates with Power Blocks, DrMOS or External
The LTC®7851/LTC7851-1 are quad output multiphase syn-
Gate Drivers and MOSFETs
chronous step-down switching regulator control ers that n
Voltage Mode Control with Accurate Current Sharing
employ a constant frequency voltage mode architecture. n
±0.75% 0.6V Voltage Reference
They maintain excel ent current balance between channels n
Quad Differential Output Voltage Sense Amplifiers
when paral eled with their internal current sharing loop. n
Multiphase Capability
Lossless DCR or a low value RSENSE is used for output n
Phase-Lockable Fixed Frequency 250kHz to 2.25MHz
current sensing. Multiple LTC7851/LTC7851-1 devices can n
Lossless Current Sensing Using Inductor DCR or
be used for high phase count operation.
Precision Current Sensing with Sense Resistor or
A very low offset, high bandwidth error amplifier, combined
DrMOS with Integrated Current Sensing
with remote output voltage sensing, provides excel ent n VCC Range: 3V to 5.5V transient response and output regulation. The LTC7851/ n VOUT Range: 0.6V to VCC – 0.5V LTC7851-1 operates with a VCC supply voltage from 3V to n Power Good Output Voltage Monitor 5.5V and is designed for step-down conversion with VIN n Output Voltage Tracking Capability with Soft-Start from 3V to 27V* and produces an output voltage from n Available in 58-Lead 5mm × 9mm QFN Package 0.6V to VCC – 0.5V.
APPLICATIONS
The LTC7851-1 is identical to the LTC7851 except it has n High Current Distributed Power Systems a lower current sense amplifier gain, making it ideal for n DSP, FPGA and ASIC Supplies DrMOS devices with internal current sense. n Datacom, Telecom and Computing Systems All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. Patents, including 6144194, 5055767. *See Note 5.
TYPICAL APPLICATION Dual-Output Converter: 1V/90A and 1.5V/30A with DrMOS
VIN 7V TO 14V VINSNS 0.25µH 0.25µH DrMOS PWM3 PWM2 DrMOS 3.57k 3.57k LTC7851 0.22µF 0.22µF ISNS3P ISNS2P ISNS3N ISNS2N VCC VCC FB2,3 VCC 5V 1µF 100k 100k 0.25µH 0.25µH V PGOOD4 PGOOD1 OUT2 VOUT1 1.5V/30A DrMOS PWM4 PWM1 DrMOS 1.0V/90A + 100µF + 330µF 3.57k RUN1 TRACK/SS1 3.57k 100µF 330µF x 2 x 3 0.22µF RUN2 TRACK/SS2 0.22µF x 6 x 9 RUN3 TRACK/SS3 PINS NOT USED IN THIS CIRCUIT: 15k ISNS4P ISNS1P 10k ISNS4N ISNS1N CLKIN VSNSP4 VSNSP1 CLKOUT VSNSN4 VSNSN1 VSNSP2 VSNSOUT4 VSNSOUT1,2,3 VSNSP3 6.04k 4.02k 10k 3.3nF 3.3nF VSNSN2 10k 15k COMP4 COMP1,2,3 10k VSNSN3 332Ω 2.2nF 100pF FB4 FB1 100pF 2.2nF 332Ω PGOOD2 FREQ IAVG1,2,3 PGOOD3 ILIM4 ILIM1,2,3 RUN4 30.9k 42.2k SGND 42.2k 100pF IAVG4 TRACK/SS4 7851 TA01 Rev A Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
FEATURES DESCRIPTION
n
Operates with Power Blocks, DrMOS or External
The LTC®7851/LTC7851-1 are quad output multiphase syn-
Gate Drivers and MOSFETs
chronous step-down switching regulator control ers that n
Voltage Mode Control with Accurate Current Sharing
employ a constant frequency voltage mode architecture. n
±0.75% 0.6V Voltage Reference
They maintain excel ent current balance between channels n
Quad Differential Output Voltage Sense Amplifiers
when paral eled with their internal current sharing loop. n
Multiphase Capability
Lossless DCR or a low value RSENSE is used for output n
Phase-Lockable Fixed Frequency 250kHz to 2.25MHz
current sensing. Multiple LTC7851/LTC7851-1 devices can n
Lossless Current Sensing Using Inductor DCR or
be used for high phase count operation.
Precision Current Sensing with Sense Resistor or
A very low offset, high bandwidth error amplifier, combined
DrMOS with Integrated Current Sensing
with remote output voltage sensing, provides excel ent n VCC Range: 3V to 5.5V transient response and output regulation. The LTC7851/ n VOUT Range: 0.6V to VCC – 0.5V LTC7851-1 operates with a VCC supply voltage from 3V to n Power Good Output Voltage Monitor 5.5V and is designed for step-down conversion with VIN n Output Voltage Tracking Capability with Soft-Start from 3V to 27V* and produces an output voltage from n Available in 58-Lead 5mm × 9mm QFN Package 0.6V to VCC – 0.5V.
APPLICATIONS
The LTC7851-1 is identical to the LTC7851 except it has n High Current Distributed Power Systems a lower current sense amplifier gain, making it ideal for n DSP, FPGA and ASIC Supplies DrMOS devices with internal current sense. n Datacom, Telecom and Computing Systems All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. Patents, including 6144194, 5055767. *See Note 5.
TYPICAL APPLICATION Dual-Output Converter: 1V/90A and 1.5V/30A with DrMOS
VIN 7V TO 14V VINSNS 0.25µH 0.25µH DrMOS PWM3 PWM2 DrMOS 3.57k 3.57k LTC7851 0.22µF 0.22µF ISNS3P ISNS2P ISNS3N ISNS2N VCC VCC FB2,3 VCC 5V 1µF 100k 100k 0.25µH 0.25µH V PGOOD4 PGOOD1 OUT2 VOUT1 1.5V/30A DrMOS PWM4 PWM1 DrMOS 1.0V/90A + 100µF + 330µF 3.57k RUN1 TRACK/SS1 3.57k 100µF 330µF x 2 x 3 0.22µF RUN2 TRACK/SS2 0.22µF x 6 x 9 RUN3 TRACK/SS3 PINS NOT USED IN THIS CIRCUIT: 15k ISNS4P ISNS1P 10k ISNS4N ISNS1N CLKIN VSNSP4 VSNSP1 CLKOUT VSNSN4 VSNSN1 VSNSP2 VSNSOUT4 VSNSOUT1,2,3 VSNSP3 6.04k 4.02k 10k 3.3nF 3.3nF VSNSN2 10k 15k COMP4 COMP1,2,3 10k VSNSN3 332Ω 2.2nF 100pF FB4 FB1 100pF 2.2nF 332Ω PGOOD2 FREQ IAVG1,2,3 PGOOD3 ILIM4 ILIM1,2,3 RUN4 30.9k 42.2k SGND 42.2k 100pF IAVG4 TRACK/SS4 7851 TA01 Rev A Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
