|
|
PDF 5962-9554701QEA Data sheet ( Hoja de datos )
| Número de pieza | 5962-9554701QEA | |
| Descripción | Dual Micropower Low-Dropout Voltage Regulators | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de 5962-9554701QEA (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
May 1999
LP2956/LP2956A
Dual Micropower Low-Dropout Voltage Regulators
General Description
The LP2956 is a micropower voltage regulator with very low
quiescent current (170 µA typical at light loads) and very low
dropout voltage (typically 60 mV at 1 mA load current and
470 mV at 250 mA load current on the main output).
The LP2956 retains all the desirable characteristics of the
LP2951, but offers increased output current (main output),
an auxiliary LDO adjustable regulated output (75 mA), and
additional features.
The auxiliary output is always on (regardless of main output
status), so it can be used to power memory circuits.
Quiescent current increases only slightly at dropout, which
prolongs battery life.
The error flag goes low if the main output voltage drops out
of regulation.
An open-collector auxiliary comparator is included, whose in-
verting input is tied to the 1.23V reference.
Reverse battery protection is provided.
The parts are available in DIP and surface mount packages.
Features
n Output voltage adjusts from 1.23V to 29V
n Guaranteed 250 mA current (main output)
n Auxiliary LDO (75 mA) adjustable output
n Auxiliary comparator with open-collector output
n Shutdown pin for main output
n Extremely low quiescent current
n Low dropout voltage
n Extremely tight line and load regulation
n Very low temperature coefficient
n Current and thermal limiting
n Reverse battery protection
Applications
n High-efficiency linear regulator
n Low dropout battery-powered regulator
n µP system regulator with switchable high-current VCC
Block Diagram
LP2956
© 1999 National Semiconductor Corporation DS011339
DS011339-1
www.national.com
1 page  
Electrical Characteristics (Continued)
Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating temperature range. Lim-
its are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods.
Unless otherwise specified: VIN = 6V, CL = 2.2 µF (Main Output) and 10 µF (Auxiliary Output), Feedback pin is tied to 5V Tap
pin, CIN = 1 µF, VSD = 0V, Main Output pin is tied to Output Sense pin, Auxiliary Output is programmed for 5V. The main
regulator output has a 1 mA load, the auxiliary regulator output has a 100 µA load.
Symbol
Parameter
Conditions
Typical LP2956AI
LP2956I
Units
Min Max Min Max
AUXILIARY COMPARATOR
HYST
IOH
VOL
IB
Hysteresis
Output “HIGH” Leakage
Output “LOW” Voltage
Input Bias Current
VOH = 30V
VIN (COMP) = 1.3V
VIN (COMP) = 1.1V
IO(COMP) = 400 µA
0 ≤ VIN (COMP) ≤ 5V
6
0.01 1
1
22
150 250 250
400 400
10 −30 30 −30 30
−50 50 −50 50
mV
µA
mV
nA
GROUND PIN CURRENT
IGND
Ground Pin Current
(Note 15)
IGND
IGND
Ground Pin Current
at Dropout (Note 15)
Ground Pin Current
at Shutdown (Note 15)
IL (Main Out) = 1 mA
IL (Aux. Out) = 0.1 mA
IL (Main Out) = 50 mA
IL (Aux. Out) = 1 mA
IL (Main Out) = 100 mA
IL (Aux. Out) = 1 mA
IL (Main Out) = 250 mA
IL (Aux. Out) = 1 mA
IL (Main Out) = 1 mA
IL (Aux. Out) = 50 mA
IL (Main Out) = 1 mA
IL (Aux. Out) = 75 mA
VIN = 4.5V
IL (Main Out) = 0.1 mA
IL (Aux. Out) = 0.1 mA
No Load on Either Output
I(SD IN) ≥ 1 µA
170
1.1
3
16
3
6
270
120
250 250 µA
280 280
22
2.5 2.5
66
88
28 28 mA
33 33
66
88
88
10 10
325 325
350 350
µA
180 180
200 200
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the de-
vice outside of its rated operating conditions.
Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, T J(max), the junction-to-ambient thermal resistance, θ J-A,
and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: P(max) =
.
Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. See Application Hints for
additional information on heat sinking and thermal resistance.
Note 3: 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 4: May exceed the input supply voltage.
Note 5: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 6: Load regulation is measured at constant junction temperature using low duty cycle pulse testing. Two separate tests are performed, one for the range of 100
µA to 1 mA and one for the 1 mA to 250 mA range. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 7: 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. At
very low values of programmed output voltage, the input voltage minimum of 2V (2.3V over temperature) must be observed.
Note 8: Thermal regulation is the change in output voltage at a time T after a change in power dissipation, excluding load or line regulation effects. Specifications
are for a 200 mA load pulse at VIN = 20V (3W pulse) for T = 10 ms on the Main regulator output. For the Auxiliary regulator output, specifications are for a 66 mA
load pulse at VIN = 20V (1W pulse) for T = 10 ms.
Note 9: Connect a 0.1 µF capacitor from the output to the feedback pin.
Note 10: Load regulation is measured at constant junction temperature using low duty cycle pulse testing. Two separate tests are performed, one for the range of
100 µA to 1 mA and one for the 1 mA to 75 mA range. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 11: Dropout dectection comparator thresholds are expressed as changes in a 5V output. To express the threshold voltages in terms of a differential at the
Feedback terminal, divide by the error amplifier gain = VOUT/V REF.
5 www.national.com
5 Page 
Application Hints (Continued)
ESR may increase by a factor of 20 or 30 as the temperature
is reduced from +25˚C to −30˚C). The value of these capaci-
tors may be increased without limit.
The main output requires less capacitance at lighter load
currents. This capacitor can be reduced to 0.68 µF for cur-
rents below 10 mA or 0.22 µF for currents below 1 mA.
Programming the main output for voltages below 5V requires
more output capacitance for stability. For the worst-case
condition of 1.23V output and 250 mA of load current, a 6.8
µF (or larger) capacitor should be used.
A 1 µF capacitor should be placed from the input pin to
ground if there is more than 10 inches of wire between the in-
put and the AC filter capacitor or if a battery input is used.
Stray capacitance to the Feedback terminal can cause insta-
bility. This problem is most likely to appear when using high
value external resistors to set the output voltage. Adding a
100 pF capacitor between the Output and Feedback pins
and increasing the output capacitance to 6.8 µF (or greater)
will cure the problem.
MINIMUM LOAD ON MAIN OUTPUT
When setting the main output voltage using an external re-
sistive divider, a minimum current of 10 µA is recommended
through the resistors to provide a minimum load.
It should be noted that a minimum load current is specified in
several of the electrical characteristic test conditions, so the
specified value must be used to obtain test limit correlation.
PROGRAMMING THE MAIN OUTPUT VOLTAGE
The main output may be pin-strapped for 5V operation using
its internal resistive divider by tying the Output and Sense
pins together and also tying the Feedback and 5V Tap pins
together.
Alternatively, it may be programmed for any voltage between
the 1.23V reference and the 29V maximum rating using an
external pair of resistors (see Figure 3 ). The complete equa-
tion for the output voltage is:
where VREF is the 1.23V reference and IFB is the Feedback
pin bias current (−20 nA typical). The minimum recom-
mended load current of 1 µA sets an upper limit of 1.2 MΩ on
the value of R2 in cases where the regulator must work with
no load (see MINIMUM LOAD).
If IFB is ignored in the calculation of the output voltage, it will
produce a small error in VMAIN OUT. Choosing R2 = 100 kΩ
will reduce this error to 0.16% (typical) while increasing the
resistor program current to 12 µA. Since the typical quies-
cent current is 130 µA, this added current is negligible.
*See Application Hints
**Drive with high to shut down
FIGURE 3. Adjustable Regulator
DS011339-11
DROPOUT VOLTAGE
The dropout voltage of the regulator is defined as the mini-
mum input-to-output voltage differential required for the out-
put voltage to stay within 100 mV of the output voltage mea-
sured with a 1V differential. The dropout voltage is
independent of the programmed output voltage.
DROPOUT DETECTION COMPARATOR
This comparator produces a logic “LOW” whenever the main
output falls out of regulation by more than about 5%. This fig-
ure results from the comparator’s built-in offset of 60 mV di-
vided by the 1.23V reference (refer to block diagram). The
5% low trip level remains constant regardless of the pro-
grammed output voltage. An out-of-regulation condition can
result from low input voltage, current limiting, or thermal lim-
iting.
Figure 4 gives a timing diagram showing the relationship be-
tween the main output voltage, the ERROR output, and input
voltage as the input voltage is ramped up and down to a
regulator whose main output is programmed for 5V. The ER-
ROR signal becomes low at about 1.3V input. It goes high at
about 5V input, where the main output equals 4.75V. Since
the dropout voltage is load dependent, the input voltage trip
points will vary with load current. The main output voltage
trip point does not vary.
The comparator has an open-collector output which requires
an external pull-up resistor. This resistor may be connected
to the regulator main output or some other supply voltage.
Using the main output prevents an invalid “HIGH” on the
comparator output which occurs if it is pulled up to an exter-
nal voltage while the regulator input voltage is reduced be-
low 1.3V. In selecting a value for the pull-up resistor, note
that while the output can sink 400 µA, this current adds to
battery drain. Suggested values range from 100 kΩ to 1 MΩ.
The resistor is not required if the output is unused.
11 www.national.com
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet 5962-9554701QEA.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| 5962-9554701QEA | Dual Micropower Low-Dropout Voltage Regulators | National Semiconductor |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |