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Linear Technology Electronic Components Datasheet

LTC1772 Datasheet

Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23

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LTC1772 pdf
LTC1772
Constant Frequency
Current Mode Step-Down
DC/DC Controller in SOT-23
FEATURES
High Efficiency: Up to 94%
High Output Currents Easily Achieved
Wide VIN Range: 2.5V to 9.8V
Constant Frequency 550kHz Operation
Burst Mode® Operation at Light Load
Low Dropout: 100% Duty Cycle
Tiny 6-Lead SOT-23 Package
0.8V Reference Allows Low Output Voltages
Current Mode Operation for Excellent Line and Load
Transient Response
Low Quiescent Current: 270µA
Shutdown Mode Draws Only 8µA Supply Current
±2.5% Reference Accuracy
U
APPLICATIO S
One or Two Lithium-Ion-Powered Applications
Cellular Telephones
Wireless Modems
Portable Computers
Distributed 3.3V, 2.5V or 1.8V Power Systems
Scanners
DESCRIPTIO
The LTC®1772 is a constant frequency current mode step-
down DC/DC controller providing excellent AC and DC load
and line regulation. The device incorporates an accurate
undervoltage lockout feature that shuts down the LTC1772
when the input voltage falls below 2.0V.
The LTC1772 provides a ±2.5% output voltage accuracy
and consumes only 270µA of quiescent current. For
applications where efficiency is a prime consideration, the
LTC1772 is configured for Burst Mode operation, which
enhances efficiency at low output current.
To further maximize the life of a battery source, the
external P-channel MOSFET is turned on continuously in
dropout (100%dutycycle).In shutdown, the device draws
a mere 8µA. High constant operating frequency of 550kHz
allows the use of a small external inductor.
The LTC1772 is available in a small footprint 6-lead
SOT-23.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
10k
220pF
16
ITH/RUN PGATE
LTC1772
2
GND
3
VFB
VIN
SENSE
5
4
R1
0.03
L1
M1 4.7µH
+
D1
C1
10µF
10V
C2A
47µF
6V
VIN
2.5V
TO 9.8V
VOUT
2.5V
C2B 2A
1µF
10V 174k
C1: TAIYO YUDEN LMK325BJ106K-T
C2A: SANYO 6TPA47M
C2B: AVX 0805ZC105KAT1A
D1: MOTOROLA MBRM120T3
L1: MURATA LQN6C-4R7
M1: FAIRCHILD FDC638P
R1: IRC LRC-LR1206-01-R030F
80.6k
1772 F01a
Figure 1. High Efficiency, High Output Current 2.5V/2A Regulator
Efficiency vs Load Current
100
VIN = 3.3V VIN = 4.2V
90
80
VIN = 6V
70 VIN = 9.8V VIN = 8.4V
60
50
40
1
VOUT = 2.5V
10 100 1000
LOAD CURRENT (mA)
10000
1772 F01b
1772fb
1


Linear Technology Electronic Components Datasheet

LTC1772 Datasheet

Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23

No Preview Available !

LTC1772 pdf
LTC1772
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage (VIN).........................– 0.3V to 10V
SENSE, PGATE Voltages ............. – 0.3V to (VIN + 0.3V)
VFB, ITH /RUN Voltages .............................– 0.3V to 2.4V
PGATE Peak Output Current (<10µs) ......................... 1A
Storage Ambient Temperature Range ... – 65°C to 150°C
Operating Temperature Range
LTC1772CS6 ........................................... 0°C to 70°C
LTC1772ES6 (Note 2) ........................ – 40°C to 85°C
LTC1772IS6 (Note 2) ......................... – 40°C to 85°C
LTC1772HS6 (Notes 2,3) ................. – 40°C to 140°C
Junction Temperature (Note 3) ............................. 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
TOP VIEW
ITH/RUN 1
GND 2
VFB 3
6 PGATE
5 VIN
4 SENSE
S6 PACKAGE
6-LEAD PLASTIC SOT-23
θJA = 230°C/ W
LTC1772CS6
LTC1772ES6
LTC1772IS6
LTC1772HS6
S6 PART MARKING
LTIL
LTIM
LTB7
LTBRY
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS The denotes specifications that apply over the full operating temperature
range, otherwise specifications are at TA = 25°C. VIN = 4.2V unless otherwise specified. (Note 2)
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Input DC Supply Current
Normal Operation
Sleep Mode
Shutdown
UVLO
Undervoltage Lockout Threshold
Shutdown Threshold (at ITH /RUN)
Typicals at VIN = 4.2V (Note 4)
2.4V VIN 9.8V
2.4V VIN 9.8V
2.4V VIN 9.8V, VITH /RUN = 0V
VIN < UVLO Threshold
VIN Falling (LTC1772C)
VIN Falling (LTC1772E, LTC1772I, LTC1772H)
VIN Rising
(LTC1772C)
(LTC1772E, LTC1772I, LTC1772H)
270 420
230 370
8 22
6 10
1.60 2.00 2.30
1.55 2.00 2.35
1.85 2.10 2.40
0.20 0.35 0.50
0.15 0.35 0.55
µA
µA
µA
µA
V
V
V
V
V
Start-Up Current Source
Regulated Feedback Voltage
VITH/RUN = 0V
(Note 5) (LTC1772C)
(Note 5) (LTC1772E, LTC1772I, LTC1772H)
0.25
0.780
0.770
0.5
0.800
0.800
0.85
0.820
0.830
µA
V
V
Output Voltage Line Regulation
Output Voltage Load Regulation
VFB Input Current
Overvoltage Protect Threshold
Overvoltage Protect Hysteresis
2.4V VIN 9.8V (Note 5)
ITH/RUN Sinking 5µA (Note 5)
ITH/RUN Sourcing 5µA (Note 5)
(Note 5)
Measured at VFB
0.820
0.05
2.5
2.5
10
0.860
20
50
0.895
mV/V
mV/µA
mV/µA
nA
V
mV
Oscillator Frequency
Gate Drive Rise Time
Gate Drive Fall Time
Peak Current Sense Voltage
VFB = 0.8V
VFB = 0V
CLOAD = 3000pF
CLOAD = 3000pF
(Note 6)
500 550 650
120
40
40
120
kHz
kHz
ns
ns
mV
1772fb
2


Part Number LTC1772
Description Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23
Maker Linear Technology
Total Page 12 Pages
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