LTC1267-ADJ_15 [Linear]
Dual High Efficiency Synchronous Step-Down Switching Regulators;
| 型号： | LTC1267-ADJ_15 |
| 厂家： | 
Linear |
| 描述： | Dual High Efficiency Synchronous Step-Down Switching Regulators |
| 文件： | 总1页 (文件大小：104K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1267
LTC1267-ADJ/LTC1267-ADJ5
Dual High Efficiency
Synchronous Step-Down
Switching Regulators
U
OBSOLETE:
Contact Linear Technology for Potential Replacement
FOR INFORMATION PURPOSES ONLY
DESCRIPTIO
EATURE
S
F
The LTC®1267 series are dual synchronous step-down
switching regulator controllers featuring automatic Burst
ModeTM operation to maintain high efficiencies at low
output currents. The LTC1267 is composed of two sepa-
rateregulatorblocks,eachdrivingapairofexternalcomple-
mentary power MOSFETs at switching frequencies up to
400kHz. The LTC1267 uses a constant off-time current-
mode architecture to provide constant ripple current in the
inductor and provide excellent line and load transient
response.
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Dual Outputs: 3.3V and 5V, Two Adjustables or
Adjustable and 5V
Wide VIN Range: 4V to 40V
Ultra-High Efficiency: Up to 95%
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Low Supply Current in Shutdown: 20µA
Current Mode Operation for Excellent Line and Load
Transient Response
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High Efficiency Maintained Over a Wide Output
Current Range
Independent Micropower Shutdown
Very Low Dropout Operation: 100% Duty Cycle
Synchronous FET Switching for High Efficiency
Available in Standard 28-Pin SSOP
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A separate pin and on-board switch allow the MOSFET
driver power to be derived from the regulated output
voltage,providingsignificantefficiencyimprovementwhen
operating at high input voltage. The output current level is
user-programmable via an external current sense resistor.
O U
PPLICATI
S
A
I
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The LTC1267 series is ideal for applications requiring dual
output voltages with high conversion efficiencies over a
wide load current range in a small amount of board space.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Modeis a trademark of Linear Technology Corporation.
Notebook and Palmtop Computers
Battery-Operated Digital Devices
Portable Instruments
DC Power Distribution Systems
U
O
TYPICAL APPLICATI
V
IN
5.4V to 25V
+
C
IN5
+
C
IN3
100µF
+
0.15µF
0.15µF
27
100µF
50V
+
3.3µF
1N4148
1N4148
50V
3.3µF
3
1
8
2
26
28
1
P-CH
P-CH
Si9435DY
Si9435DY
L3
20µH
V
CAP3
V
V
MSHDN CAP5 EXT V
V
CC5
CC3
CC
IN
CC
PGATE 5
4
5
25
24
18
L5
33µH
R
R
SENSE5
SENSE3
0.05Ω
0.1µF
PGATE 3
0.1µF
V
0.05Ω
V
5V
2A
OUT3
3.3V
2A
OUT5
PDRIVE 3
+
PDRIVE 5
+
14
SENSE
3
SENSE
SENSE
5
5
1000pF
1000pF
LTC1267
17
19
13
12
–
–
SENSE
3
SHDN5
SHDN3
D3
MBRS140T3
D5
6
23
NGATE 3
PGND3 SGND3
11
NGATE 5
MBRS140T3
C
C
I
I
SGND5
20
PGND5
22
T5
16
T3
9
TH3
10
TH5
15
N-CH
Si9410DY
C
OUT5
N-CH
Si9410DY
C
OUT3
+
+
220µF
7
220µF
10V
10V
× 2
C
C
C5
C
C
× 2
C3
3300pF 3300pF
T3
T5
270pF
270pF
R
C5
1k
R
C3
1k
R
: KRL SL-1R050J
R
: KRL SL-1R050J
SENSE3
SENSE5
L3: COILTRONICS CTX20-4
L5: COILTRONICS CTX33-4
LTC1267 • F01
SHDN3, SHDN5, MSHDN
0V = NORMAL, >2V = SHDN
Figure 1. High Efficiency Dual 3.3V, 5V
1
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