LT1585 Linear Technology, LT1585 Datasheet - Page 11

• Manufacturer Part Number: LT1585
• Description: 7A/ 4.6A/ 3A Low Dropout Fast Response Positive Regulators Adjustable and Fixed
• Manufacturer: Linear Technology

TYPICAL APPLICATIONS
486 and DX4 are trademarks of Intel Corporation.
APPLICATIONS
This is the lowest resistance path for heat flow. Proper
mounting ensures the best thermal flow from this area of
the package to the heat sink. Linear Technology strongly
recommends thermal compound at the case-to-heat sink
interface. Use a thermally conductive spacer if the case of
the device must be electrically isolated and include its
contribution to the total thermal resistance. Please consult
“Mounting Considerations for Power Semiconductors”
1990 Linear Applications Handbook, Volume I , Pages
RR3-1 to RR3-20. The output connects to the case of all
devices in the LT1584/LT1585/LT1587 series.
For example, using an LT1585CT-3.3 (TO-220, commer-
cial) and assuming:
4.75V TO
5.25V
V
I
T
OUT
A
CASE-TO-HEAT SINK
IN
= 70 C,
(Max Continuous) = 5.25V (5V + 5%), V
C1 TO C3
AVX TPS
= 4.6A
3 EACH
220 F
10V
AVX X7R 0805
HEAT SINK
+
Minimum Parts Count LT1585 Adjustable Circuit
330nF
V
16V
THERMALLOY
IN
IN
C4
U
7020B-MT
LT1585CT
Recommended LT1587-3.45 Circuit for the Intel 486
for the Intel Pentium VRE Processor
= 1 C/W (with Thermal Compound)
4.75V
ADJ
= 4 C/W
INFORMATION
OUT
U
+
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
C1
10 F
10V
R1
110
0.1%
R2
197
0.1%
U
IN
LT1587-3.45
W
GND
AVX CORP. [phone]
THERMALLOY INC. [phone]
DO NOT SUBSTITUTE COMPONENTS.
N
+
OUT
PLACE IN MICROPROCESSOR
C5 TO C10
100 F
10V
AVX TPS
4 EACH
OUT
U
SOCKET CAVITY
+
C2
22 F
10V
= 3.3V,
ESR OF THE 47 F IS <0.1
PLACE AT MICROPROCESSOR SOCKET V
+
C11 TO C20
1 F
16V
AVX Y5V 0805
24 EACH
C3 TO C6
47 F
10V
3.50V
4.6A
Power dissipation under these conditions is equal to:
Junction temperature will be equal to:
For the Control Section:
For the Power Transistor:
In both cases the junction temperature is below the maxi-
mum rating for the respective sections, ensuring reliable
operation.
1584/5/7 TA04
P
T
T
121.3 C < 125 C = T
range)
T
142 C < 150 C = T
Range)
J
J
J
D
= T
= 70 C + 9W (4 C/W + 1 C/W + 3 C/W) = 142 C
TM
= 70 C + 9W (4 C/W + 1 C/W + 0.7 C/W) = 121.3 C
= (V
C7 TO C15
0.1 F
DX4
A
IN
+ P
TM
– V
Overdrive Microprocessor
D
(
OUT
HEAT SINK
50mV/DIV
LT1584/LT1585/LT1587
C16 TO C24
0.01 F
2A/DIV
)(I
V
CC
I
3.45V
3A
OUT
OUT
JMAX
OUT
LT1584 • TA03
PINS
JMAX
* TRANSIENT RESPONSE MEASURED WITH AN INTEL
) = (5.25 – 3.3)(4.6) = 9W
POWER VALIDATOR. V
POWER VALIDATOR
+
(Power Transistor Commercial
(Control Section Commercial
LT1585 Transient Response
for 3.8A Load Current Step*
CASE-TO-HEAT SINK
100 s/DIV
OUT
IS MEASURED AT THE
+
11
JC
LT1584 • TA05
)