POWER LOSS (W)
LTC3822
No R , Low Input
SENSE
Voltage, Synchronous Step-Down
DC/DC Controller
FEATURES DESCRIPTION
n
No Current Sense Resistor Required
The LTC 3822 is a synchronous step-down switching
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All N-Channel MOSFET Synchronous Drive
regulator controller that drives external N-channel power
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High Current Outputs Possible
MOSFETs using few external components. The constant
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Constant Frequency Current Mode Operation for
frequency current mode architecture with MOSFET V
DS
Excellent Line and Load Transient Response
sensing eliminates the need for sense resistors and im-
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V : 2.75V to 4.5V
proves ef ciency.
IN
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1% 0.6V Reference
A maximum duty cycle of 99% provides low dropout
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Low Dropout Operation: 99% Duty Cycle
operation. The switching frequency can be programmed
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Selectable Frequency (300kHz/550kHz/750kHz)
up to 750kHz, allowing the use of small surface mount
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Internal Soft-Start Circuitry
inductors and capacitors.
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Selectable Maximum Peak Current Sense Threshold
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The LTC3822 is available in thermally enhanced DFN and
Digital RUN Control Pin
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10-lead MSOP packages.
Output Overvoltage Protection
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Micropower Shutdown: I = 7.5A
Q L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
No R is a trademark of Linear Technology Corporation. All other trademarks are the
SENSE
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Tiny Thermally Enhanced Leadless (3mm 3mm)
property of their respective owners. Protected by U.S. Patents, including 5481178, 5929620,
6580258, 6304066, 5847554, 6611131, 6498466.
DFN or 10-Lead MSOP Package
APPLICATIONS
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3.3V Systems
IN
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Li-Ion Battery Systems
TYPICAL APPLICATION
1.8V/8A High Ef ciency, 550kHz Step-Down Converter Ef ciency and Power Loss vs
Load Current
100 10
V = 3.3V
V
IN IN
IPRG V
IN
2.75V TO 4.5V 90
EFFICIENCY
47F
80
RUN
FDS6898A
TG
70
1
FREQ
SW 0.47H
60
V
OUT
LTC3822
0.22F
I
1.8V
TH
50
8A
BOOST
100F
5.1k
40
POWER LOSS
0.1
680pF
30
GND BG
20
V
FB
10
59k 118k
0 0.01
100 1000 10000
3822 TA01
LOAD CURRENT (mA)
3822 TA01b
3822fa
1
EFFICIENCY (%)LTC3822
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage (V ) ....................... 0.3V to 4.5V Operating Temperature Range
IN
BOOST Voltage .......................................... 0.3V to 10V (Note 2) ............................................... 40C to 85C
FREQ, RUN, IPRG Voltages ............0.3V to (V + 0.3V) Storage Ambient Temperature Range..... 65C to 125C
IN
V , I Voltages ...................................... 0.3V to 2.4V Junction Temperature (Note 3) ............................ 125C
FB TH
SW Voltage ........................................... 2V to V + 1V Lead Temperature
IN
TG, BG Peak Output Current (<10s) ......................... 1A (Soldering, 10 sec, MSE only) .......................... 300C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
BG 10 RUN
1
BG 1 10 RUN
TG 2 9 I
TH TG 2 9 I
TH
11 11
BOOST 3 8 V
BOOST 3 8 V FB
FB
V 4 7 IPRG
IN
V 4 7 IPRG
IN
SW 5 6 FREQ
SW 5 6 FREQ
MSE PACKAGE
10-LEAD PLASTIC MSOP
DD PACKAGE
T = 125C, = 40C/W
JMAX JA
10-LEAD (3mm s 3mm) PLASTIC DFN
EXPOSED PAD IS GND
T = 125C, = 43C/W
JMAX JA
(MUST BE SOLDERED TO PCB)
EXPOSED PAD IS GND
(MUST BE SOLDERED TO PCB)
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3822EDD#PBF LTC3822EDD#TRPBF LCBF 10-Lead (3mm 3mm) Plastic DFN 40C to 85C
LTC3822EMSE#PBF LTC3822EMSE#TRPBF LTCBG 10-Lead Plastic MSOP 40C to 85C
Consult LTC Marketing for parts speci ed with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based nish parts.
For more information on lead free part marking, go to: