LT1587-1.5 Linear Technology, LT1587-1.5 Datasheet

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LT1587-1.5

Manufacturer Part Number
LT1587-1.5
Description
Fixed 1.5V/ 3A Low Dropout Fast Response GTL + Regulator
Manufacturer
Linear Technology
Datasheet
FEATURES
APPLICATIONS
TYPICAL
3.3V
Fast Transient Response
Guaranteed Dropout Voltage at Multiple Currents
Load Regulation: 0.05% Typ
Trimmed Current Limit
On-Chip Thermal Limiting
Intel Pentium
Low Voltage Logic Supplies
Battery-Powered Circuitry
+
C1
100 F
10V
AVX TPS
V
IN
LT1587-1.5
GND
APPLICATION
®
V
OUT
Pro Processor GTL + Supply
U
+
V
3A
TT
C2, C3
100 F
10V
AVX TPS
= 1.5V
RX
TX
C4 TO
C6
1 F
U
RX
TX
R1
75
R2
150
V
Intel Pentium Pro Processor GTL + Supply
REF
Q1
C13
0.1 F
Q3
R5
100
142 TOTAL SIGNAL LINES
R7
100
Pentium is a registered trademark of Intel Corporation
DESCRIPTION
The LT
with a fixed 1.5V output voltage and 3A output current
capability. The design is optimized for low voltage applica-
tions where transient response and minimum input voltage
are critical. Similar to the LT1085, it has lower dropout and
faster transient response. These improvements make it
ideal for low voltage microprocessor applications, espe-
cially as the regulator in an Intel Pentium Pro processor
GTL + supply.
Current limit is trimmed to ensure specified output current
and controlled short-circuit current. On-chip thermal lim-
iting provides protection against any combination of over-
load that creates excessive junction temperatures.
The LT1587-1.5 is available in both the through-hole and
surface mount versions of the industry standard 3-pin
TO-220 power package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
R8
100
Q4
®
R6
100
1587-1.5 is a low dropout 3-terminal regulator
V
Q2
REF
C14
0.1 F
R3
75
R4
150
RX
TX
U
NOTE: LTC RECOMMENDS SEPARATE
V
TO ENSURE CURRENT SHARING
BETWEEN THE REGULATORS AND TO
MINIMIZE V
GTL + Regulator
TT
RX
TX
C10 TO C12
1 F
GENERATORS AT EACH BUS END
Fast Response
V
Fixed 1.5V, 3A
TT
= 1.5V
Low Dropout
TT
3A
DISTRIBUTION DROPS
+
C8, C9
100 F
10V
AVX TPS
V
OUT
LT1587-1.5
LT1587-1.5
GND
V
LT1587 • TA01
IN
+
C7
100 F
10V
AVX TPS
3.3V
1

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LT1587-1.5 Summary of contents

Page 1

... On-chip thermal lim- iting provides protection against any combination of over- load that creates excessive junction temperatures. The LT1587-1.5 is available in both the through-hole and surface mount versions of the industry standard 3-pin TO-220 power package. , LTC and LT are registered trademarks of Linear Technology Corporation. ...

Page 2

... Note 1: See thermal regulation specifications for changes in output voltage due to heating effects. Load and line regulation are measured at a constant junction temperature by low duty cycle pulse testing. Note 2: Line and load regulation are guaranteed up to the maximum power dissipation (17W for the LT1587-1 package). Power 2 U RATINGS Storage Temperature Range ................. – ...

Page 3

... OUTPUT CURRENT (A) LT1587 • TPC01 Output Voltage vs Temperature 1.53 1.52 1.51 1.50 1.49 1.48 1.47 –75 –50 – TEMPERATURE ( C) Ripple Rejection vs Frequency LT1587-1.5: (V – OUT 0. RIPPLE OUT FULL LOAD 0 10 100 1k FREQUENCY (Hz) Short-Circuit Current vs Temperature 5.0 4.5 4.0 3.5 3.0 –75 –50 – 100 ...

Page 4

... Stability The circuit design in the LT1587-1.5 requires the use of an output capacitor as part of the frequency compensation. For all operating conditions, the addition solid tantalum or a 100 F aluminum electrolytic on the output ensures stability ...

Page 5

... Only with large values of output capacitance, such as 1000 F to 5000 F, and with the input pin instantaneously shorted to ground can dam- age occur. A crowbar circuit at the input of the LT1587-1.5 can generate those levels of current, and a diode from output to input is then recommended. This is shown in CAPACITANCE Figure 2 ...

Page 6

... IN GND Figure 3. Connection for Best Load Regulation Thermal Considerations The LT1587-1.5 protects the device under overload condi- tions with internal power and thermal limiting circuitry. However, for normal continuous load conditions, do not exceed maximum junction temperature ratings impor- tant to consider all sources of thermal resistance from junction-to-ambient ...

Page 7

... TYP LT1587-1.5 0.165 – 0.180 (4.191 – 4.572) 0.045 – 0.055 (1.143 – 1.397) +0.008 0.004 –0.004 0.059 (1.499) +0 ...

Page 8

... LT1587-1.5 RELATED PARTS PART NUMBER DESCRIPTION ® LTC 1392 Micropower Temperature, Power Supply and Differential Voltage Monitor LTC1430 High Power Step-Down Switching Regulator Controller LTC1472 Protected PCMCIA V LT1580 Very Low Dropout 7A Linear Regulator Linear Technology Corporation 8 1630 McCarthy Blvd., Milpitas, CA 95035-7417 ...

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