LT1580/LT1580-2.5
7A, Very Low
Dropout Regulator
FEATURES
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DESCRIPTION
The LT ®1580 is a 7A low dropout regulator designed to
power the new generation of microprocessors. The drop-
out voltage of this device is 100mV at light loads rising to
just 540mV at 7A. To achieve this dropout, a second low
current input voltage 1V greater than the output voltage, is
required. The device can also be used as a single supply
device where dropout is comparable to an LT1584.
Several other new features have been added to the LT1580.
A remote SENSE pin is brought out. This feature virtually
eliminates output voltage variations due to load changes.
Typical load regulation, measured at the SENSE pin, for a
load current step of 100mA to 7A is less than 1mV.
The LT1580 has fast transient response, equal to the
LT1584. On fixed voltage devices, the ADJ pin is brought
out. A small capacitor on the ADJ pin further improves
transient response.
This device is ideal for generating processor supplies of
2V to 3V on motherboards where both 5V and 3.3V
supplies are available.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Pentium is a registered trademark of Intel Corporation.
PowerPC is a trademark of IBM Corporation.
Low Dropout, 540mV at 7A Output Current
Fast Transient Response
Remote Sense
1mV Load Regulation
Fixed 2.5V Output and Adjustable Output
No Supply Sequencing Problems in
Dual Supply Mode
APPLICATIONS
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s
s
s
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Microprocessor Supplies
Post Regulators for Switching Supplies
High Current Regulators
5V to 3.XXV for Pentium
®
Processors Operating
at 90MHz to 166MHz and Beyond
3.3V to 2.9V for Portable Pentium Processor
PowerPC
TM
Series Power Supplies
TYPICAL APPLICATION
Dropout Voltage —
Minimum Power Voltage
2.5V Microprocessor Supply
3.3V
7A
V
POWER
V
OUT
1.0
MINIMUM POWER VOLTAGE (V)
2.5V/7A
INDICATES GUARANTEED TEST POINTS
0°C
≤
T
J
≤
125°C
+
330µF
OS-CON
+
LT1580-2.5
100µF TANT
AVX TPS
×
7
0.5
T
J
= 125°C
T
J
= 25°C
5V
0.2A
V
CONTROL
SENSE
ADJ
0.1µF
1580 TA01
+
10µF
TANT
GND
0
0
1
3
5
4
2
OUTPUT CURRENT (A)
6
7
1580 G03
U
U
U
DATA SHEET LIMIT
1
LT1580/LT1580-2.5
ABSOLUTE
MAXIMUM
RATINGS
V
POWER
Input Voltage ................................................ 6V
V
CONTROL
Input Voltage ........................................... 13V
Storage Temperature ............................ – 65°C to 150°C
Operating Junction Temperature Range
Control Section
LT1580C ........................................... 0°C to 125°C
LT1580I ........................................ – 40°C to 125°C
Power Transistor
LT1580C ........................................... 0°C to 150°C
LT1580I ........................................ – 40°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
PRECONDITIONING
100% Thermal Limit Functional Test
PACKAGE/ORDER INFORMATION
FRONT VIEW
5
TAB
IS
OUTPUT
4
3
2
1
Q PACKAGE
5-LEAD PLASTIC DD
V
POWER
V
CONTROL
V
OUT
ADJ
SENSE
ORDER PART
NUMBER
LT1580CQ
LT1580IQ
TAB
IS
OUTPUT
FRONT VIEW
5
4
3
2
1
T PACKAGE
5-LEAD PLASTIC TO-220
V
POWER
V
CONTROL
V
OUT
ADJ
SENSE
θ
JA
= 30°C/ W
θ
JA
= 50°C/ W
FRONT VIEW
7
6
5
4
3
2
1
R PACKAGE
7-LEAD PLASTIC DD
NC
V
POWER
ADJ
V
OUT
V
CONTROL
GND
SENSE
ORDER PART
NUMBER
LT1580CR-2.5
LT1580IR-2.5
TAB
IS
OUTPUT
FRONT VIEW
7
6
5
4
3
2
1
T7 PACKAGE
7-LEAD PLASTIC TO-220
NC
V
POWER
ADJ
V
OUT
V
CONTROL
GND
SENSE
TAB
IS
OUTPUT
θ
JA
= 30°C/ W
θ
JA
= 50°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER
Output Voltage: LT1580-2.5
(Note 1)
MIN
2.485
2.475
2.475
2.460
1.243
1.237
1.237
1.232
q
q
CONDITIONS
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 0mA
V
CONTROL
= 4V to 12V, V
POWER
= 3V to 5.5V, I
LOAD
= 0mA to 4A
V
CONTROL
= 4V to 12V, V
POWER
= 3V to 5.5V,
I
LOAD
= 0mA to 7A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 4V to 12V, V
POWER
= 3V to 5.5V,
I
LOAD
= 0mA to 6.5A, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 2.75V, V
POWER
= 2V, I
LOAD
= 10mA
V
CONTROL
= 2.7V to 12V, V
POWER
= 1.75V to 5.5V, I
LOAD
= 10mA to 4A
V
CONTROL
= 2.7V to 12V, V
POWER
= 2.05V to 5.5V,
I
LOAD
= 10mA to 7A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 2.7V to 12V, V
POWER
= 2.05V to 5.5V,
I
LOAD
= 10mA to 6.5A, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 3.65V to 12V, V
POWER
= 3V to 5.5V, I
LOAD
= 10mA
V
CONTROL
= 2.5V to 12V, V
POWER
= 1.75V to 5.5V, I
LOAD
= 10mA
Reference Voltage: LT1580
(V
ADJ
= 0V)
Line Regulation: LT1580-2.5
LT1580
2
UU
U
U
U
W
W W
U
W
ORDER PART
NUMBER
LT1580CT
LT1580IT
ORDER PART
NUMBER
LT1580CT7-2.5
LT1580IT7-2.5
q
TYP
2.500
2.500
2.500
2.500
1.250
1.250
1.250
1.250
1
1
MAX
2.515
2.525
2.525
2.525
1.257
1.263
1.263
1.263
3
3
UNITS
V
V
V
V
V
V
V
V
mV
mV
q
LT1580/LT1580-2.5
ELECTRICAL CHARACTERISTICS
PARAMETER
Load Regulation: LT1580-2.5
LT1580 (V
ADJ
= 0V)
Minimum Load Current: LT1580
Control Pin Current: LT1580-2.5
(Note 4)
CONDITIONS
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 0mA to 7A
V
CONTROL
= 2.75V, V
POWER
= 2.1V, I
LOAD
= 10mA to 7A
V
CONTROL
= 5V, V
POWER
= 3.3V, V
ADJ
= 0V (Note 3)
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 100mA, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 100mA, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 4A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 4A, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 5V, V
POWER
= 3V, I
LOAD
= 4A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 5V, V
POWER
= 3V, I
LOAD
= 4A, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 7A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 6.5A, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
LOAD
= 100mA, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
LOAD
= 100mA, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
LOAD
= 4A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
LOAD
= 4A, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 2.75V, V
POWER
= 1.75V, I
LOAD
= 4A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 2.75V, V
POWER
= 1.75V, I
LOAD
= 4A, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
LOAD
= 7A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
LOAD
= 6.5A, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 5V, V
POWER
= 3.3V, I
LOAD
= 0mA
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
LOAD
= 10mA
V
CONTROL
= 5V, V
POWER
= 3.3V,
∆V
OUT
= 100mV, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 5V, V
POWER
= 3.3V,
∆V
OUT
= 100mV, – 40°C
≤
T
J
< 0°C
V
CONTROL
= 2.75V, V
POWER
= 2.05V,
∆V
OUT
= 100mV, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 2.75V, V
POWER
= 2.05V,
∆V
OUT
= 100mV, – 40°C
≤
T
J
< 0°C
V
C
= V
P
= 5V Avg, V
RIPPLE
= 1V
P-P
, I
OUT
= 4A, T
J
= 25°C
V
C
= V
P
= 3.75V Avg, V
RIPPLE
= 1V
P-P
, V
ADJ
= 0V, I
OUT
= 4A, T
J
= 25°C
30ms Pulse
q
q
MIN
q
q
q
TYP
1
1
5
6
30
33
60
6
30
33
60
6
50
MAX
5
5
10
10
12
60
70
70
80
120
130
10
12
60
70
70
80
120
130
10
120
UNITS
mV
mV
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
µA
A
A
A
A
dB
dB
Control Pin Current: LT1580
(Note 4)
Ground Pin Current: LT1580-2.5
ADJ Pin Current: LT1580 (V
ADJ
= 0V)
Current Limit: LT1580-2.5
LT1580 (V
ADJ
= 0V)
Ripple Rejection: LT1580-2.5
LT1580
Thermal Regulation
Dropout Voltage (Note 2)
Minimum V
CONTROL
: LT1580-2.5
(V
CONTROL
– V
OUT
)
7.1
6.6
7.1
6.6
60
60
8
8
80
80
0.002
0.65/2.70
1.00
1.00
1.06
1.15
1.00
1.00
1.05
1.06
1.15
1.15
1.20
1.15
1.20
1.20
1.25
1.30
1.35
1.15
1.20
1.15
1.20
1.18
1.23
1.20
1.25
1.30
1.35
0.020
%/W
°C/W
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Thermal Resistance, Junction-to-Case T, T7 Packages, Control Circuitry/Power Transistor
V
POWER
= 3.3V, I
LOAD
= 100mA, 0°C
≤
T
J
≤
125°C
V
POWER
= 3.3V, I
LOAD
= 100mA, – 40°C
≤
T
J
< 0°C
V
POWER
= 3.3V, I
LOAD
= 1A, 0°C
≤
T
J
≤
125°C
V
POWER
= 3.3V, I
LOAD
= 1A, – 40°C
≤
T
J
< 0°C
V
POWER
= 3.3V, I
LOAD
= 4A, 0°C
≤
T
J
≤
125°C
V
POWER
= 3.3V, I
LOAD
= 4A, – 40°C
≤
T
J
< 0°C
V
POWER
= 3.3V, I
LOAD
= 7A, 0°C
≤
T
J
≤
125°C
V
POWER
= 3.3V, I
LOAD
= 6.5A, – 40°C
≤
T
J
< 0°C
V
POWER
= 2.05V, I
LOAD
= 100mA, 0°C
≤
T
J
≤
125°C
V
POWER
= 2.05V, I
LOAD
= 100mA, – 40°C
≤
T
J
< 0°C
V
POWER
= 2.05V, I
LOAD
= 1A, 0°C
≤
T
J
≤
125°C
V
POWER
= 2.05V, I
LOAD
= 1A, – 40°C
≤
T
J
< 0°C
V
POWER
= 2.05V, I
LOAD
= 2.75A, 0°C
≤
T
J
≤
125°C
V
POWER
= 2.05V, I
LOAD
= 2.75A, – 40°C
≤
T
J
< 0°C
V
POWER
= 2.05V, I
LOAD
= 4A, 0°C
≤
T
J
≤
125°C
V
POWER
= 2.05V, I
LOAD
= 4A, – 40°C
≤
T
J
< 0°C
V
POWER
= 2.05V, I
LOAD
= 7A, 0°C
≤
T
J
≤
125°C
V
POWER
= 2.05V, I
LOAD
= 6.5A, – 40°C
≤
T
J
< 0°C
Minimum V
CONTROL
: LT1580
(V
CONTROL
– V
OUT
)
(V
ADJ
= 0V)
3
LT1580/LT1580-2.5
ELECTRICAL CHARACTERISTICS
PARAMETER
Minimum V
POWER
: LT1580-2.5
(V
POWER
– V
OUT
)
CONDITIONS
V
CONTROL
= 5V, I
LOAD
= 100mA
V
CONTROL
= 5V, I
LOAD
= 1A
V
CONTROL
= 5V, I
LOAD
= 4A, T
J
= 25°C
V
CONTROL
= 5V, I
LOAD
= 4A
V
CONTROL
= 5V, I
LOAD
= 7A, T
J
= 25°C
V
CONTROL
= 5V, I
LOAD
= 7A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 5V, I
LOAD
= 6.5A, – 40°C
≤
T
J
≤
0°C
V
CONTROL
= 2.75V, I
LOAD
= 100mA
V
CONTROL
= 2.75V, I
LOAD
= 1A
V
CONTROL
= 2.75V, I
LOAD
2.75A
V
CONTROL
= 2.75V, I
LOAD
= 4A, T
J
= 25°C
V
CONTROL
= 2.75V, I
LOAD
= 4A
V
CONTROL
= 2.75V, I
LOAD
= 7A, T
J
= 25°C
V
CONTROL
= 2.75V, I
LOAD
= 7A, 0°C
≤
T
J
≤
125°C
V
CONTROL
= 2.75V, I
LOAD
= 6.5A, – 40°C
≤
T
J
≤
0°C
MIN
q
q
q
TYP
0.10
0.15
0.34
0.54
0.70
0.70
MAX
0.17
0.22
0.40
0.50
0.62
0.80
0.80
0.17
0.22
0.38
0.40
0.50
0.62
0.80
0.80
UNITS
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Minimum V
POWER
: LT1580
(V
POWER
– V
OUT
)
(V
ADJ
= 0V)
q
q
q
q
0.10
0.15
0.26
0.34
0.54
0.70
0.70
The
q
denotes specifications which apply over the full operating
temperature range.
Note 1:
Unless otherwise specified V
OUT
= V
SENSE
. For the LT1580
adjustable device V
ADJ
= 0V.
Note 2:
For the LT1580, dropout is caused by either minimum control
voltage (V
CONTROL
) or minimum power voltage (V
POWER
). Both parameters
are specified with respect to the output voltage. The specifications represent
the minimum input/output voltage required to maintain 1% regulation.
Note 3:
For the LT1580 adjustable device the minimum load current is the
minimum current required to maintain regulation. Normally the current in
the resistor divider used to set the output voltage is selected to meet the
minimum load current requirement.
Note 4:
The control pin current is the drive current required for the output
transistor. This current will track output current with roughly a 1:100 ratio.
The minimum value is equal to the quiescent current of the device.
TYPICAL PERFORMANCE CHARACTERISTICS
Control Pin Current
vs Output Current
140
120
CONTROL PIN CURRENT (mA)
100
DATA SHEET LIMIT
80
60
40
20
0
0
1
4
3
5
2
OUTPUT CURRENT (A)
6
7
TYPICAL
DEVICE
INDICATES GUARANTEED TEST POINTS
0°C
≤
T
J
≤
125°C
2
MINIMUM POWER VOLTAGE (V)
INDICATES GUARANTEED TEST POINTS
0°C
≤
T
J
≤
125°C
MINIMUM CONTROL VOLTAGE
(V
CONTROL
– V
OUT
) (V)
4
U W
1580 G01
Minimum Control Voltage
1.0
Dropout Voltage —
Minimum Power Voltage
INDICATES GUARANTEED TEST POINTS
0°C
≤
T
J
≤
125°C
DATA SHEET LIMIT
1
T
J
= 125°C
T
J
= 25°C
DATA SHEET LIMIT
0.5
T
J
= 125°C
T
J
= 25°C
0
0
1
3
5
4
2
OUTPUT CURRENT (A)
6
7
1580 G02
0
0
1
3
5
4
2
OUTPUT CURRENT (A)
6
7
1580 G03
LT1580/LT1580-2.5
TYPICAL PERFORMANCE CHARACTERISTICS
LT1580 Reference Voltage
vs Temperature
1.258
1.256
REFERENCE VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.254
1.252
1.250
1.248
1.246
1.244
1.242
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
1580 G04
PIN FUNCTIONS
(5-Lead/7-Lead)
SENSE (Pin 1):
This pin is the positive side of the reference
voltage for the device. With this pin it is possible to Kelvin
sense the output voltage at the load.
ADJ (Pin 2/5):
This pin is the negative side of the
reference voltage for the device. Transient response can
be improved by adding a small bypass capacitor from the
ADJ pin to ground. For fixed voltage devices the ADJ pin
is also brought out to allow the user to add a bypass
capacitor.
GND (Pin 2, 7-Lead Only):
For fixed voltage devices this
is the bottom of the resistor divider that sets the output
voltage.
U W
LT1580-2.5 Output Voltage
vs Temperature
2.508
2.506
2.504
2.502
2.500
2.498
2.496
2.494
2.492
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
1580 G05
Load Current Step Response
V
OUT
50mV/DIV
7A
LOAD
400mA
50µs/DIV
1580 TA02
U
U
U
V
POWER
(Pin 5/6):
This is the collector to the power device
of the LT1580. The output load current is supplied through
this pin. For the device to regulate, the voltage at this pin
must be between 0.1V and 0.8V greater than the output
voltage (see Dropout specifications).
V
CONTROL
(Pin 4/3):
This pin is the supply pin for the
control circuitry of the device. The current flow into this
pin will be about 1% of the output current. For the device
to regulate, the voltage at this pin must be between 1.0V
and 1.3V greater than the output voltage (see Dropout
specifications).
V
OUT
(Pin 3/4):
This is the power output of the device.
5
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