Datasheet LT1528 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 3A Low Dropout Regulator for Microprocessor Applications |
| Pages / Page | 12 / 1 — FEATURES. DESCRIPTION. Dropout Voltage: 0.6V at IOUT = 3A. Fast Transient … |
| File Format / Size | PDF / 170 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Dropout Voltage: 0.6V at IOUT = 3A. Fast Transient Response. Output Current: 3A. APPLICATIONS
Model Line for this Datasheet
Text Version of Document
LT1528 3A Low Dropout Regulator for Microprocessor Applications
FEATURES DESCRIPTION
n
Dropout Voltage: 0.6V at IOUT = 3A
The LT ®1528 is a 3A low dropout regulator optimized to n
Fast Transient Response
handle the large load current transients associated with n
Output Current: 3A
the current generation of microprocessors. This device has n Quiescent Current: 400μA the fastest transient response of currently available PNP n No Protection Diodes Needed regulators and is very tolerant of variations in capacitor n Fixed Output Voltage: 3.3V ESR. Dropout voltage is 75mV at 10mA, rising to 300mV n Controlled Quiescent Current in Dropout at 1A and 600mV at 3A. The device has a quiescent cur- n Shutdown IQ = 125μA rent of 400μA. Quiescent current is well controlled; it does n Stable with 3.3μF Output Capacitor not increase signifi cantly as the device enters dropout. n Reverse Battery Protection The regulator can operate with output capacitors as small n No Reverse Output Current as 3.3μF, although larger capacitors will be needed to n Thermal Limiting achieve the performance required in most microprocessor applications. The LT1528 is available with a fi xed output voltage of 3.3V. An external SENSE pin allows adjustment
APPLICATIONS
to output voltages greater than 3.3V, using a simple resis- tive divider. This allows the device to be adjusted over a n Microprocessor Applications wide range of output voltages, including the 3.3V to 4.2V n Post Regulator for Switching Supplies range required by a variety of processors from Intel, IBM, n 5V to 3.3V Logic Regulator 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 Dropout Voltage
0.6 5 1 IN OUT VOUT 0.5 + 15Ω 68Ω 4 × 47μF* VIN =5V LT1528 SOLID TANTALUM J1 J2 J3 0.4 4 2 SHDN SENSE TAGE (V) GND 0.3 330Ω 3 0.2 DROPOUT VOL
VSHDN (PIN 4) OUTPUT SHORTING VOUT
*CHOOSE CAPACITORS TO MEET PROCESSOR 0.1 <0.25 OFF J1 3.30 REQUIREMENTS >2.80 ON J2 3.45 NC ON J3 4.00 0 1528 TA01 0 0.5 1.0 1.5 2.0 2.5 3.0 OUTPUT CURRENT (mA) 1528 TA02 1528fb 1
FEATURES DESCRIPTION
n
Dropout Voltage: 0.6V at IOUT = 3A
The LT ®1528 is a 3A low dropout regulator optimized to n
Fast Transient Response
handle the large load current transients associated with n
Output Current: 3A
the current generation of microprocessors. This device has n Quiescent Current: 400μA the fastest transient response of currently available PNP n No Protection Diodes Needed regulators and is very tolerant of variations in capacitor n Fixed Output Voltage: 3.3V ESR. Dropout voltage is 75mV at 10mA, rising to 300mV n Controlled Quiescent Current in Dropout at 1A and 600mV at 3A. The device has a quiescent cur- n Shutdown IQ = 125μA rent of 400μA. Quiescent current is well controlled; it does n Stable with 3.3μF Output Capacitor not increase signifi cantly as the device enters dropout. n Reverse Battery Protection The regulator can operate with output capacitors as small n No Reverse Output Current as 3.3μF, although larger capacitors will be needed to n Thermal Limiting achieve the performance required in most microprocessor applications. The LT1528 is available with a fi xed output voltage of 3.3V. An external SENSE pin allows adjustment
APPLICATIONS
to output voltages greater than 3.3V, using a simple resis- tive divider. This allows the device to be adjusted over a n Microprocessor Applications wide range of output voltages, including the 3.3V to 4.2V n Post Regulator for Switching Supplies range required by a variety of processors from Intel, IBM, n 5V to 3.3V Logic Regulator 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 Dropout Voltage
0.6 5 1 IN OUT VOUT 0.5 + 15Ω 68Ω 4 × 47μF* VIN =5V LT1528 SOLID TANTALUM J1 J2 J3 0.4 4 2 SHDN SENSE TAGE (V) GND 0.3 330Ω 3 0.2 DROPOUT VOL
VSHDN (PIN 4) OUTPUT SHORTING VOUT
*CHOOSE CAPACITORS TO MEET PROCESSOR 0.1 <0.25 OFF J1 3.30 REQUIREMENTS >2.80 ON J2 3.45 NC ON J3 4.00 0 1528 TA01 0 0.5 1.0 1.5 2.0 2.5 3.0 OUTPUT CURRENT (mA) 1528 TA02 1528fb 1
