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PDF LP2954 Data sheet ( Hoja de datos )
| Número de pieza | LP2954 | |
| Descripción | 5V and Adjustable Micropower Low-Dropout Voltage Regulators | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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June 1999
LP2954/LP2954A
5V and Adjustable Micropower Low-Dropout Voltage
Regulators
General Description
The LP2954 is a 5V micropower voltage regulator with very
low quiescent current (90 µA typical at 1 mA load) and very
low dropout voltage (typically 60 mV at light loads and
470 mV at 250 mA load current).
The quiescent current increases only slightly at dropout
(120 µA typical), which prolongs battery life.
The LP2954 with a fixed 5V output is available in the
three-lead TO-220 and TO-263 packages. The adjustable
LP2954 is provided in an 8-lead surface mount, small outline
package. The adjustable version also provides a resistor net-
work which can be pin strapped to set the output to 5V.
Reverse battery protection is provided.
The tight line and load regulation (0.04% typical), as well as
very low output temperature coefficient make the LP2954
well suited for use as a low-power voltage reference.
Output accuracy is guaranteed at both room temperature
and over the entire operating temperature range.
Features
n 5V output within 1.2% over temperature (A grade)
n Adjustable 1.23 to 29V output voltage available
(LP2954IM and LP2954AIM)
n Guaranteed 250 mA output current
n Extremely low quiescent current
n Low dropout voltage
n Reverse battery protection
n Extremely tight line and load regulation
n Very low temperature coefficient
n Current and thermal limiting
n Pin compatible with LM2940 and LM340 (5V version
only)
n Adjustable version adds error flag to warn of output drop
and a logic-controlled shutdown
Applications
n High-efficiency linear regulator
n Low dropout battery-powered regulator
Package Outline and Ordering Information
TO-220 3–Lead Plastic Package
SO-8 Small Outline Surface Mount
DS011128-2
Front View
Order Number LP2954AIT or LP2954IT
See NS Package T03B
DS011128-33
Top View
Order Number LP2954AIM or LP2954IM
See NS Package M08A
© 1999 National Semiconductor Corporation DS011128
www.national.com
1 page  
Electrical Characteristics (Continued)
TABLE 1. Typical Values of Case-to-Heatsink
Thermal Resistance (˚C/W) (Data from AAVID Eng.)
Silicone grease
Dry interface
Mica with grease
1.0
1.3
1.4
TABLE 2. Typical Values of Case-to-Heatsink
Thermal Resistance (˚C/W) (Data from Thermalloy)
Thermasil III
Thermasil II
Thermalfilm (0.002) with grease
1.3
1.5
2.2
Note 3: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 4: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested separately for load regulation in the load
ranges 0.1 mA–1 mA and 1 mA–250 mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 5: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below the value measured with a 1V differential.
Note 6: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground pin current.
Note 7: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation
effects. Specifications are for 200 mA load pulse at VIN = 20V (3W pulse) for T = 10 ms.
Note 8: When used in dual-supply systems where the regulator load is returned to a negative supply, the output voltage must be diode-clamped to ground.
Note 9: Connect a 0.1µF capacitor from the output to the feedback pin.
Note 10: VREF≤VOUT≤(VIN−1V), 2.3V≤VIN≤30V, 100µA≤IL≤250mA.
Note 11: Two seperate tests are performed, one covering VIN=2.5V to VO(NOM)+1V and the other test for VIN=2.5V to VO(NOM)+1V to 30V.
Note 12: VSHUTDOWN≤1.1V, VOUT=VO(NOM).
Note 13: Comparator thresholds are expressed in terms of a voltage differential at the Feedback terminal below the nominal reference voltage measured at
VIN=VO(NOM)+1V. To express these thresholds in terms of output voltage change, multiply by the Error amplifier gain, which is VOUT/VREF=(R1+R2)/R2.
Note 14: Human body model, 200pF discharged through 1.5kΩ.
Typical Performance Characteristics
Quiescent Current
Quiescent Current
Ground Pin Current vs Load
DS011128-12
Ground Pin Current
Ground Pin Current
DS011128-13
Output Noise Voltage
DS011128-14
DS011128-15
DS011128-16
5
DS011128-17
www.national.com
5 Page 
Physical Dimensions inches (millimeters) unless otherwise noted
TO-220 3-Lead Plastic Package
Order Number LP2954AIT or LP2954IT
NS Package T03B
11 www.national.com
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet LP2954.PDF ] | |
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