Datasheet LTC3822-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | No RSENSE , Low Input Voltage, Synchronous Step-Down DC/DC Controller |
| Pages / Page | 24 / 1 — FEATURES. DESCRIPTION. Dual N-Channel MOSFET Synchronous Drive. No … |
| File Format / Size | PDF / 389 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Dual N-Channel MOSFET Synchronous Drive. No Current Sense Resistor Required
Model Line for this Datasheet
Text Version of Document
LTC3822-1 No RSENSETM, Low Input Voltage, Synchronous Step-Down DC/DC Controller
FEATURES DESCRIPTION
■
Dual N-Channel MOSFET Synchronous Drive
The LTC®3822-1 is a synchronous step-down switching ■
No Current Sense Resistor Required
regulator controller that drives external N-channel power ■
Optimized for 3.3VIN and Li-Ion Applications
MOSFETs using few external components. The constant ■ Constant Frequency Current Mode Operation for frequency current mode architecture with MOSFET VDS Excellent Line and Load Transient Response sensing eliminates the need for sense resistors and im- ■ ±1% 0.6V Reference proves effi ciency. ■ Low Dropout Operation: 99% Duty Cycle Burst Mode operation provides high effi ciency at light ■ Phase-Lockable or Adjustable Frequency: loads. The 99% maximum duty cycle provides low dropout 250kHz to 750kHz operation, extending operating time in battery-powered ■ Internal Soft-Start Circuitry systems. ■ Tracking and Adjustable Soft-Start Input ■ Selectable Maximum Peak Current Sense Threshold The operating frequency can be programmed up to 750kHz, ■ Selectable Burst Mode®/ Forced Continuous/Pulse allowing the use of small surface mount inductors and ca- Skipping Mode at Light Load pacitors. For noise sensitive applications, the LTC3822-1 ■ Digital RUN Control Pin can be synchronized to an external clock from 250kHz to ■ Output Overvoltage Protection 750kHz. ■ Micropower Shutdown: IQ = 7.5µA The LTC3822-1 is available in the tiny footprint thermally ■ Tiny Thermally Enhanced 12-Pin (3mm × 3mm) DFN enhanced 12-pin DFN package or 16-pin narrow SSOP or 16-Pin Narrow SSOP Packages package.
APPLICATIONS LTC3822-1 LTC3822
Light Load Continuous, Discontinuous Discontinuous Mode ■ Single Cell Li-Ion Powered Systems Operation or Burst Mode Operation ■ 3.3V Package DD12 (3mm × 3mm), GN16 DD10 (3mm × 3mm), IN Systems MS10E , LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Tracking/Soft-Start Yes Internal Soft-Start Only Corporation. No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. External Sync Yes No Protected by Patents, including 5481178, 5929620, 6580258, 6304066, 5847554, PGOOD Pin GN16 Only No 6611131, 6498466, 5705919.
TYPICAL APPLICATION Effi ciency/Power Loss vs Load Current
100 10 90 V Burst Mode IPRG V IN IN 80 47µF 3.3V EFFICIENCY RUN 1 ×2 POWER LOSS (W) 70 PLLLPF TG LTC3822-1 60 0.47µH I SW V TH OUT 50 0.1 1.8V 10.2k BOOST 47µF 8A 40 Burst Mode SYNC/MODE ×2 POWER LOSS 0.1µF EFFICIENCY (%) 30 1nF TRACK/SS 0.01 GND BG 20 VIN = 3.3V V 10 V FB GND OUT = 1.8V FIGURE 10 CIRCUIT 0 0.001 38221 TA01 10 100 1000 10000 59k 118k LOAD CURRENT (mA) 38221 TA01b 38221f 1
FEATURES DESCRIPTION
■
Dual N-Channel MOSFET Synchronous Drive
The LTC®3822-1 is a synchronous step-down switching ■
No Current Sense Resistor Required
regulator controller that drives external N-channel power ■
Optimized for 3.3VIN and Li-Ion Applications
MOSFETs using few external components. The constant ■ Constant Frequency Current Mode Operation for frequency current mode architecture with MOSFET VDS Excellent Line and Load Transient Response sensing eliminates the need for sense resistors and im- ■ ±1% 0.6V Reference proves effi ciency. ■ Low Dropout Operation: 99% Duty Cycle Burst Mode operation provides high effi ciency at light ■ Phase-Lockable or Adjustable Frequency: loads. The 99% maximum duty cycle provides low dropout 250kHz to 750kHz operation, extending operating time in battery-powered ■ Internal Soft-Start Circuitry systems. ■ Tracking and Adjustable Soft-Start Input ■ Selectable Maximum Peak Current Sense Threshold The operating frequency can be programmed up to 750kHz, ■ Selectable Burst Mode®/ Forced Continuous/Pulse allowing the use of small surface mount inductors and ca- Skipping Mode at Light Load pacitors. For noise sensitive applications, the LTC3822-1 ■ Digital RUN Control Pin can be synchronized to an external clock from 250kHz to ■ Output Overvoltage Protection 750kHz. ■ Micropower Shutdown: IQ = 7.5µA The LTC3822-1 is available in the tiny footprint thermally ■ Tiny Thermally Enhanced 12-Pin (3mm × 3mm) DFN enhanced 12-pin DFN package or 16-pin narrow SSOP or 16-Pin Narrow SSOP Packages package.
APPLICATIONS LTC3822-1 LTC3822
Light Load Continuous, Discontinuous Discontinuous Mode ■ Single Cell Li-Ion Powered Systems Operation or Burst Mode Operation ■ 3.3V Package DD12 (3mm × 3mm), GN16 DD10 (3mm × 3mm), IN Systems MS10E , LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Tracking/Soft-Start Yes Internal Soft-Start Only Corporation. No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. External Sync Yes No Protected by Patents, including 5481178, 5929620, 6580258, 6304066, 5847554, PGOOD Pin GN16 Only No 6611131, 6498466, 5705919.
TYPICAL APPLICATION Effi ciency/Power Loss vs Load Current
100 10 90 V Burst Mode IPRG V IN IN 80 47µF 3.3V EFFICIENCY RUN 1 ×2 POWER LOSS (W) 70 PLLLPF TG LTC3822-1 60 0.47µH I SW V TH OUT 50 0.1 1.8V 10.2k BOOST 47µF 8A 40 Burst Mode SYNC/MODE ×2 POWER LOSS 0.1µF EFFICIENCY (%) 30 1nF TRACK/SS 0.01 GND BG 20 VIN = 3.3V V 10 V FB GND OUT = 1.8V FIGURE 10 CIRCUIT 0 0.001 38221 TA01 10 100 1000 10000 59k 118k LOAD CURRENT (mA) 38221 TA01b 38221f 1
