LTC1267-ADJ_15 [Linear]

Dual High Efficiency Synchronous Step-Down Switching Regulators;
LTC1267-ADJ_15
型号: LTC1267-ADJ_15
厂家: Linear    Linear
描述:

Dual High Efficiency Synchronous Step-Down Switching Regulators

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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.  
I
Dual Outputs: 3.3V and 5V, Two Adjustables or  
Adjustable and 5V  
Wide VIN Range: 4V to 40V  
Ultra-High Efficiency: Up to 95%  
I
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Low Supply Current in Shutdown: 20µA  
Current Mode Operation for Excellent Line and Load  
Transient Response  
I
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  
I
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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
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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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