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LTC3822-1_15 Datasheet, PDF (1/24 Pages) Linear Technology – No RSENSE, Low Input Voltage, Synchronous Step-Down DC/DC Controller | |||
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LTC3822-1
FEATURES
No RSENSETM, Low Input
Voltage, Synchronous
Step-Down DC/DC Controller
DESCRIPTION
â Dual N-Channel MOSFET Synchronous Drive
â No Current Sense Resistor Required
â Optimized for 3.3VIN and Li-Ion Applications
â Constant Frequency Current Mode Operation for
Excellent Line and Load Transient Response
â ±1% 0.6V Reference
â Low Dropout Operation: 99% Duty Cycle
â Phase-Lockable or Adjustable Frequency:
250kHz to 750kHz
â Internal Soft-Start Circuitry
â Tracking and Adjustable Soft-Start Input
â Selectable Maximum Peak Current Sense Threshold
â Selectable Burst Mode®/ Forced Continuous/Pulse
Skipping Mode at Light Load
â Digital RUN Control Pin
â Output Overvoltage Protection
â Micropower Shutdown: IQ = 7.5µA
â Tiny Thermally Enhanced 12-Pin (3mm à 3mm) DFN
or 16-Pin Narrow SSOP Packages
APPLICATIONS
â Single Cell Li-Ion Powered Systems
â 3.3VIN Systems
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. No RSENSE is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by Patents, including 5481178, 5929620, 6580258, 6304066, 5847554,
6611131, 6498466, 5705919.
The LTC®3822-1 is a synchronous step-down switching
regulator controller that drives external N-channel power
MOSFETs using few external components. The constant
frequency current mode architecture with MOSFET VDS
sensing eliminates the need for sense resistors and im-
proves efï¬ciency.
Burst Mode operation provides high efï¬ciency at light
loads. The 99% maximum duty cycle provides low dropout
operation, extending operating time in battery-powered
systems.
The operating frequency can be programmed up to 750kHz,
allowing the use of small surface mount inductors and ca-
pacitors. For noise sensitive applications, the LTC3822-1
can be synchronized to an external clock from 250kHz to
750kHz.
The LTC3822-1 is available in the tiny footprint thermally
enhanced 12-pin DFN package or 16-pin narrow SSOP
package.
LTC3822-1
LTC3822
Light Load
Operation
Continuous, Discontinuous Discontinuous Mode
or Burst Mode Operation
Package
DD12 (3mm à 3mm), GN16 DD10 (3mm à 3mm),
MS10E
Tracking/Soft-Start Yes
Internal Soft-Start Only
External Sync
Yes
No
PGOOD Pin
GN16 Only
No
TYPICAL APPLICATION
10.2k
1nF
IPRG
VIN
RUN
PLLLPF TG
LTC3822-1
ITH
SW
BOOST
SYNC/MODE
TRACK/SS
GND
BG
VFB
GND
59k 118k
0.47µH
0.1µF
VIN
47µF
3.3V
Ã2
47µF
Ã2
VOUT
1.8V
8A
38221 TA01
Efï¬ciency/Power Loss vs Load Current
100
10
90
Burst Mode
80
EFFICIENCY
1
70
60
50
40
30
20
10
0
10
0.1
Burst Mode
POWER LOSS
0.01
VIN = 3.3V
VOUT = 1.8V
FIGURE 10 CIRCUIT 0.001
100
1000
10000
LOAD CURRENT (mA) 38221 TA01b
38221f
1
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