1528C Datasheet PDF - Linear Technology


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1528C
Linear Technology

Part Number 1528C
Description LT1528C
Page 12 Pages

1528C datasheet pdf
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LT1528
3A Low Dropout Regulator
for Microprocessor Applications
FEATURES
n Dropout Voltage: 0.6V at IOUT = 3A
n Fast Transient Response
n Output Current: 3A
n Quiescent Current: 400μA
n No Protection Diodes Needed
n Fixed Output Voltage: 3.3V
n Controlled Quiescent Current in Dropout
n Shutdown IQ = 125μA
n Stable with 3.3μF Output Capacitor
n Reverse Battery Protection
n No Reverse Output Current
n Thermal Limiting
APPLICATIONS
n Microprocessor Applications
n Post Regulator for Switching Supplies
n 5V to 3.3V Logic Regulator
DESCRIPTION
The LT ®1528 is a 3A low dropout regulator optimized to
handle the large load current transients associated with
the current generation of microprocessors. This device has
the fastest transient response of currently available PNP
regulators and is very tolerant of variations in capacitor
ESR. Dropout voltage is 75mV at 10mA, rising to 300mV
at 1A and 600mV at 3A. The device has a quiescent cur-
rent of 400μA. Quiescent current is well controlled; it does
not increase significantly as the device enters dropout.
The regulator can operate with output capacitors as small
as 3.3μF, although larger capacitors will be needed to
achieve the performance required in most microprocessor
applications. The LT1528 is available with a fixed output
voltage of 3.3V. An external SENSE pin allows adjustment
to output voltages greater than 3.3V, using a simple resis-
tive divider. This allows the device to be adjusted over a
wide range of output voltages, including the 3.3V to 4.2V
range required by a variety of processors from Intel, IBM,
AMD, and Cyrix.
The LT1528 has both reverse input and reverse output
protection and includes a shutdown feature. Quiescent
current drops to 125μA in shutdown. The LT1528 is avail-
able in 5-lead TO-220 and 5-lead DD-PAK packages.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
TYPICAL APPLICATION
Microprocessor Supply with Shutdown
5 IN
OUT 1
VIN =5V
LT1528
4 SHDN
SENSE 2
GND
3
VOUT
15Ω 68Ω + 4 × 47μF*
SOLID TANTALUM
J1 J2
J3
330Ω
VSHDN (PIN 4)
<0.25
>2.80
NC
OUTPUT
OFF
ON
ON
SHORTING
J1
J2
J3
VOUT
3.30
3.45
4.00
*CHOOSE CAPACITORS
TO MEET PROCESSOR
REQUIREMENTS
1528 TA01
Dropout Voltage
0.6
0.5
0.4
0.3
0.2
0.1
0
0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (mA)
1528 TA02
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LT1528
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Voltage........................................................ ±15V*
OUTPUT Pin Reverse Current ................................10mA
SENSE Pin Current.................................................10mA
SHDN Pin Input Voltage (Note 2)..................6.5V, – 0.3V
SHDN Pin Input Current (Note 2).............................5mA
Output Short-Circuit Duration .......................... Indefinite
Storage Temperature Range................... –65°C to 150°C
Operating Junction Temperature Range
LT1528C................................................ 0°C to 125°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
*For applications requiring input voltage ratings greater than 15V,
contact the factory.
PIN CONFIGURATION
FRONT VIEW
TAB IS
GND
5 VIN
4 SHDN
3 GND
2 SENSE
1 OUTPUT
Q PACKAGE
5-LEAD PLASTIC DD
TJMAX = 125°C, θJA = 30°C/ W
TAB IS
GND
FRONT VIEW
5
4
3
2
1
T PACKAGE
5-LEAD PLASTIC TO-220
TJMAX = 125°C, θJA = 50°C/ W
VIN
SHDN
GND
SENSE
OUTPUT
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LT1528CQ#PBF
LT1528CQ#TRPBF
LT1528CQ
5-Lead Plastic DD-PAK
LT1528CT#PBF
LT1528CT#TRPBF
LT1528CT
5-Lead Plastic TO-220
LEAD BASED FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LT1528CQ
LT1528CQ#TR
LT1528CQ
5-Lead Plastic DD-PAK
LT1528CT
LT1528CT#TR
LT1528CT
5-Lead Plastic TO-220
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
TEMPERATURE RANGE
0°C to 125°C
0°C to 125°C
TEMPERATURE RANGE
0°C to 125°C
0°C to 125°C
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TJ = 25°C.
PARAMETER
Regulated Output Voltages (Notes 3, 4)
Line Regulation (Note 4)
Load Regulation (Note 4)
Dropout Voltage (Note 5)
CONDITIONS
VIN = 3.8V, IOUT = 1mA
4.3V < VIN < 15V, 1mA < IOUT < 3A
ΔVIN = 3.8V to 15V, IOUT = 1mA
ΔILOAD = 1mA to 3A, VIN = 4.3V
ΔILOAD = 1mA to 3A, VIN = 4.3V
ILOAD = 10mA
ILOAD = 10mA
MIN
3.250
l 3.200
l
l
l
TYP
3.300
3.300
1.5
12
15
70
MAX
3.350
3.400
1.0
20
30
110
150
UNITS
V
V
mV
mV
mV
mV
mV
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LT1528
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TJ = 25°C.
PARAMETER
CONDITIONS
MIN TYP MAX
Dropout Voltage (Note 5)
GND Pin Current (Note 6)
SENSE Pin Current (Notes 4, 8)
ILOAD = 100mA
ILOAD = 100mA
ILOAD = 700mA
ILOAD = 700mA
ILOAD = 1.5A
ILOAD = 1.5A
ILOAD = 3A
ILOAD = 3A
ILOAD = 0mA
ILOAD = 0mA, TJ = 125°C (Note 7)
ILOAD = 100mA
ILOAD = 100mA, TJ = 125°C (Note 7)
ILOAD = 300mA
ILOAD = 300mA, TJ = 125°C (Note 7)
ILOAD = 700mA
ILOAD = 700mA, TJ = 125°C (Note 7)
ILOAD = 1.5A
ILOAD = 3A
l
l
l
l
l
l
90
150 200
250
280 320
420
390 450
600
570 670
850
450 750
1.9
1.2 2.5
2.7
2.6 4.0
4.1
7.3 12.0
8.8
22 40
85 140
130 250
SHDN Threshold
SHDN Pin Current (Note 9)
VOUT = Off-to-On
VOUT = On-to-Off
VSHDN = 0V
l 1.20 2.80
l 0.25
0.75
l 37 100
Quiescent Current in Shutdown (Note 10)
VIN = 6V, VSHDN = 0V
l 110 220
Ripple Rejection
Current Limit
Input Reverse Leakage Current
VIN – VOUT = 1V(Avg), VRIPPLE = 0.5VP-P,
fRIPPLE = 120Hz, ILOAD = 1.5A
VIN – VOUT = 7V
VIN = 4.3V, ΔVOUT = – 0.1V
VIN = – 15V, VOUT = 0V
50 67
l 3.2
4.5
4.0
l 1.0
Reverse Output Current (Note 11)
VOUT = 3.3V, VIN = 0V
120 250
UNITS
mV
mV
mV
mV
mV
mV
mV
mV
μA
mA
mA
mA
mA
mA
mA
mA
mA
mA
μA
V
V
μA
μA
dB
A
A
mA
μA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The SHDN pin input voltage rating is required for a low
impedance source. Internal protection devices connected to the SHDN
pin will turn on and clamp the pin to approximately 7V or – 0.6V. This
range allows the use of 5V logic devices to drive the pin directly. For
high impedance sources or logic running on supply voltages greater than
5.5V, the maximum current driven into the SHDN pin must be less than
5mA.
Note 3: Operating conditions are limited by maximum junction
temperature. The regulated output voltage specification will not apply
for all possible combinations of input voltage and output current. When
operating at maximum input voltage, the output current must be limited.
When operating at maximum output current, the input voltage range
must be limited.
Note 4: The LT1528 is tested and specified with the SENSE pin
connected to the OUTPUT pin.
Note 5: Dropout voltage is the minimum input/output voltage required to
maintain regulation at the specified output current. In dropout the output
voltage will be equal to: (VIN – VDROPOUT).
Note 6: GND pin current is tested with VIN = VOUT (nominal) and a
current source load. This means that the device is tested while operating
in its dropout region. This is the worst-case GND pin current. The GND
pin current will decrease slightly at higher input voltages.
Note 7: GND pin current will rise at TJ > 75°C. This is due to internal
circuitry designed to compensate for leakage currents in the output
transistor at high temperatures. This allows quiescent current to be
minimized at lower temperatures, yet maintain output regulation at high
temperatures with light loads. See quiescent current curve in typical
performance characteristics section.
Note 8: SENSE pin current flows into the SENSE pin.
Note 9: SHDN pin current at VSHDN = 0V flows out of the SHDN pin.
Note 10: Quiescent current in shutdown is equal to the total sum of the
SHDN pin current (40μA) and the GND pin current (70μA).
Note 11: Reverse output current is tested with the input pin grounded
and the OUTPUT pin forced to the rated output voltage. This current
flows into the OUTPUT pin and out of the GND pin.
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LT1528
TYPICAL PERFORMANCE CHARACTERISTICS
Guaranteed Dropout Voltage
1.0
= TEST POINTS
0.9
0.8
0.7
0.6 TJ ≤ 125°C
0.5
0.4 TJ ≤ 25°C
0.3
0.2
0.1
0
0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
1528 TPC01
Quiescent Current
2000
1750
ILOAD = 0
RLOAD =
1500
1250
1000
750
500 VSHDN = OPEN (HIGH)
250 VSHDN = 0V
0
0 1 2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
1528 TPC04
GND Pin Current
100
TJ = 25°C
90 VOUT = VSENSE
80 *FOR VOUT = 3.3V
70
60
RL = 1.1Ω
50 ILOAD = 3A*
40
RL = 2.2Ω
30 ILOAD = 1.5A* RL = 4.7Ω
ILOAD = 700mA*
20
10
0
0 1 2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
1528 TPC07
4
Dropout Voltage
0.8
0.7
0.6 ILOAD = 3A
0.5
0.4 ILOAD = 700mA
0.3
ILOAD = 1.5A
0.2
0.1
0
–50 –25
ILOAD = 300mA
ILOAD = 10mA
0 25 50 75
TEMPERATURE (°C)
100 125
1528 TPC02
SENSE Pin Voltage
3.400
ILOAD = 1mA
3.375
3.350
3.325
3.300
3.275
3.250
3.225
3.200
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
1528 TPC05
GND Pin Current
100 VIN = 3.3V
90 DEVICE IS OPERATING
IN DROPOUT
80
70
TJ = 125°C
60 TJ = 25°C
50
40
30 TJ = –50°C
20
10
0
0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
1528 TPC08
Quiescent Current
2.00
VIN = 4.3V
1.75 RL =
1.50
1.25
1.00
0.75
0.50 VSHDN = OPEN
0.25 VSHDN = 0V
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
1528 TPC03
GND Pin Current
7
TJ = 25°C
6
VOUT = VSENSE
*FOR VOUT = 3.3V
5 RL = 6.6Ω
ILOAD = 500mA*
4
RL = 11Ω
3 ILOAD = 300mA*
2
RL = 33Ω
ILOAD = 100mA*
1
RL = 330Ω: ILOAD = 10mA*
0
0 1 2 3 4 5 6 7 8 9 10
INPUT VOLTAGE (V)
1528 TPC06
SHDN Pin Threshold
(On-to-Off)
2.0
ILOAD = 1mA
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
1528 TPC09
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