|
|
PDF SPX2920 Data sheet ( Hoja de datos )
| Número de pieza | SPX2920 | |
| Descripción | Low Drop Out Voltage Regulator | |
| Fabricantes | Sipex Corporation | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de SPX2920 (archivo pdf) en la parte inferior de esta página. Total 10 Páginas | ||
|
No Preview Available !
www.DataSheet4U.com
®
SPX2920
400mA Low Drop Out Voltage Regulator with Shutdown
FEATURES
■ Output 3.3V, 5.0V, at 400mA Output
■ Very Low Quiescent Current
■ Low Dropout Voltage
■ Extremely Tight Load And Line Regulation
■ Very Low Temperature Coefficient
■ Current & Thermal Limiting
■ Error Flag Warns Of Output Dropout
(for SO-8)
■ Logic-Controlled Electronic Shutdown
(for SO-8)
■ Output Programmable From 1.24V to 20V
(for SO-8)
■ Equivalent Replacement for MIC2920A and
MIC2904
+VIN
100K
SHUTDOWN
INPUT
OFF
ON
8 +VIN
1
VOUT
SPX2920 FB 7
SD
3
______
ERROR
GND
5
4
1.2V to 20V
+
R1 0.01µF 10µF
VREF
R2
ERROR
OUTPUT
Adjustable Regulator
VIN
+
0.1 µF
IN OUT
SPX2920
GND
IG
5V
+
2.2 µF
5V Regulator Circuit
DESCRIPTION
The SPX2920 is a low power voltage regulator. This device is an excellent choice for use in battery-powered
applications such as cordless telephones, radio control systems, and portable computers. The SPX2920
features very low quiescent current (140µA Typ.) and very low dropout voltage. This includes a tight initial
tolerance of 1% max and very low output temperature coefficient, making the SPX2920 useful as a low-
power voltage reference.
The error flag output feature is used as power-on reset for warning of a low output voltage, due to a falling
voltage input of batteries. Another feature is the logic-compatible shutdown input which enables the
regulator to be switched on and off. The SPX2920 is offered in 3-pin TO-220 package, SO-8 (same pin
out as SPX2951), SOT-223, and surface mount and 3-pin TO-263 packages.
The regulator output voltage (of the SO-8) may be pin-strapped for a 3.3V and 5.0V or programmed from
1.24V to 20V with an external pair of resistors.
TO-220-3 (U)
SPX2920
123
TO-263-3 (T)
SPX2920
1 23
8-Pin Surface Mount
SOT-223 (M3)
VOUT
SENSE
SHUTDOWN
GND
18
27
SPX2920
36
45
VIN
FEEDBACK
5V/ 3.3V TAP
ERROR
SPX2920
1 23
VIN GND VOUT
VIN GND VOUT
Front View
VIN GND VOUT
Top View
Top View
Top View
Rev: A Date: 03/30/04
SPX2920 400mA Low Drop Out Voltage Regulator with Shutdown
1
©Copyright 2004 Sipex Corporation
1 page  
Error Detection Comparator Output
The Comparator produces a logic low output
whenever the SPX2920 output falls out of regu-
lation by more than around 5%. This is around
60mV offset divided by the 1.235 reference
voltage. This trip level remains 5% below
normal regardless of the programmed output
voltage of the regulator. Figure 1 shows the
timing diagram depicting the ERROR signal
and the regulator output voltage as the SPX2920
input is ramped up and down. The ERROR
signal becomes low at around 1.3V input, and
goes high around 5V input (input voltage at
which VOUT = 4.75). Since the SPX2920’s
dropout voltage is load dependent, the input
voltage trip point (around 5V) will vary with the
load current. The output voltage trip point
(approx. 4.75V) does not vary with load.
The error comparator has an open-collector out-
put, which requires an external pull-up resistor.
Depending on the system requirements the re-
sistor may be returned to 5V output or other
supply voltage. In determining the value of this
resistor, note that the output is rated to sink
400µA; this value adds to battery drain in a low
battery condition. Suggested values range from
100K to 1MΩ. If the output is unused this
resistor is not required.
Programming the Output Voltage of
SPX2920
The SPX2920 may be pin-strapped for 5V or
3.3V using its internal voltage divider by tying
Pin 1 (output) to Pin 2 (sense) and Pin 7 (feed-
back) to Pin 6 (5V/3.3V Tap).
Also, it may be programmed for any output
voltage between its 1.235V reference and its
20V maximum rating. As seen on the front
page, an external pair of resistors is required.
Refer to the below equation for the program-
ming of the output voltage::
VOUT = VREF x ( 1 + R1/ R2 )+ IFBR1
The VREF is 1.235 and IFB is the feedback bias
current, nominally -20nA. The minimum rec-
ommended load current of 1µA forces an upper
limit of 1.2MΩ on value of R2. If no load is
presented the I produces an error of typically
FB
2% in VOUT, which may be eliminated at room
temperature by trimming R1. To improve the
accuracy choose the value of R2 = 100k; this
reduces the error by 0.17% and increases the
resistor program current by 12µA. Since the
SPX2920 typically draws 60 µA at no load with
Pin 2 open-circuited this is a small price to pay.
Reducing Output Noise
It may be an advantage to reduce the AC noise
present at the output. One way is to reduce the
regulator bandwidth by increasing the size of
the output capacitor. This is the only way that
noise can be reduced on the 3 lead SPX2920 but
is relatively inefficient, as increasing the ca-
pacitor from 1µF to 220µF only decreases the
noise from 430µV to 160µV Vrms for a 100kHz
bandwidth at 5V output.
Noise could also be reduced fourfold by a by-
pass capacitor across R1, since it reduces the
high frequency gain from 4 to unity. Pick
C
BYPASS
≅1
/
2πR1
x
200
Hz
or choose 0.01µF. When doing this, the output
capacitor must be increased to 3.3µF to main-
tain stability. These changes reduce the output
noise from 430µV to 100µV Vrms for a 100kHz
bandwidth at 5V output. With the bypass ca-
pacitor added, noise no longer scales with out-
put voltage so that improvements are more dra-
matic at higher output voltages.
4.75V
OUTPUT
VOLTAGE
_______
ERROR*
INPUT
VOLTAGE
+5.0V
+1.3V
* See Application Info.
+
+
Figure 1. ERROR Output Timing
Rev: A Date: 03/30/04
SPX2920 400mA Low Drop Out Voltage Regulator with Shutdown
5
©Copyright 2004 Sipex Corporation
5 Page | ||
| Páginas | Total 10 Páginas | |
| PDF Descargar | [ Datasheet SPX2920.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| SPX2920 | Low Drop Out Voltage Regulator | Sipex Corporation |
| 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 |