Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

SPX2954AN-3.3 Datasheet(PDF) 8 Page - Sipex Corporation

Part # SPX2954AN-3.3
Description  250mA Low Dropout Voltage Regulator
Download  17 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  SIPEX [Sipex Corporation]
Direct Link  http://www.sipex.com
Logo SIPEX - Sipex Corporation

SPX2954AN-3.3 Datasheet(HTML) 8 Page - Sipex Corporation

Back Button SPX2954AN-3.3 Datasheet HTML 4Page - Sipex Corporation SPX2954AN-3.3 Datasheet HTML 5Page - Sipex Corporation SPX2954AN-3.3 Datasheet HTML 6Page - Sipex Corporation SPX2954AN-3.3 Datasheet HTML 7Page - Sipex Corporation SPX2954AN-3.3 Datasheet HTML 8Page - Sipex Corporation SPX2954AN-3.3 Datasheet HTML 9Page - Sipex Corporation SPX2954AN-3.3 Datasheet HTML 10Page - Sipex Corporation SPX2954AN-3.3 Datasheet HTML 11Page - Sipex Corporation SPX2954AN-3.3 Datasheet HTML 12Page - Sipex Corporation Next Button
Zoom Inzoom in Zoom Outzoom out
 8 / 17 page
background image
Rev. 3/6/03
SP2954 250mA Low Dropout Voltage Regulator
© Copyright 2003 Sipex Corporation
8
EXTERNAL CAPACITORS
The stability of the SPX2954 requires a 1
µF or
greater capacitor between output and ground.
Oscillation could occur without this capacitor.
Most types of tantalum or aluminum electro-
lytic works fine here. For operations below
-25
°C solid tantalum is recommended since the
many aluminum types have electrolytes that
freeze at about -30
°C. The ESR of about 5Ω or
less and resonant frequency above 500kHz are
the most important parameters in the value of
the capacitor. The capacitors value may be in-
creased without limit.
At lower values of output current, less output
capacitance is required for stability. For the
currents below 10mA the value of the capacitor
can be reduced to 0.33
µF and 0.1µF for 1mA.
More output capacitance is needed for the 8-pin
version at voltages below 5V since it runs the
error amplifier at lower gain. At worst case 3.3
µF or greater must be used for the condition of
150mA load at 1.23V output.
The SPX2954 unlike other low dropout regula-
tors will remain stable and in regulation with no
load in addition to the internal voltage divider.
This feature is especially important in applica-
tions like CMOS RAM keep-alive. When set-
ting the output voltage of the SPX2954 version
with external resistors, a minimum load of 1
µA
is recommended
If there is more than 10 inches of wire between
the input and the AC filter capacitor or if a
battery is used as the input then a 1
µF tantalum
or aluminum electrolytic capacitor should be
placed from the input to the ground.
Instability can occur if there is stray capacitance
to the SPX2954 feedback terminal (pin 7). This
could cause more problems when using a higher
value of external resistors to set the output
voltage. This problem can be fixed by adding a
100pF capacitor between output and feedback
and increasing the output capacitor to at least
3.3
µF.
ERROR DETECTION COMPARATOR
OUTPUT
The comparator produces a logic low output
whenever the SPX2954 output falls out of regu-
lation by more than around 5%. This is around
60 mV offset divided by the 1.235 reference
voltage. This trip level remains 5% below nor-
mal regardless of the programmed output volt-
age of the regulator.
Figure 1 shows the timing diagram depicting the
ERROR signal and the regulator output voltage
as the SPX2954 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 V
OUT
= 4.75). Since the
SPX2954’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
400mA, this value adds to battery drain in a low
battery condition. Suggested values range from
100k to 1M
Ω. If the output is unused this resis-
tor is not required.
PROGRAMMING
THE
OUTPUT
VOLTAGE OF SPX2954
The SPX2954 may be pin-strapped for 5V using
its internal voltage divider by tying Pin 1 (out-
put) to Pin 2 (sense) and Pin 7 (feedback) to Pin
6 (5V Tap). Also, it may be programmed for any
output voltage between its 1.235V reference
and its 30V maximum rating using an external
pair of resistors. Refer to the below equation for
the programming of the output voltage:
V
OUT = VREF x (1 + R1/R2)+ IFBR1
The V
REF is 1.235 and IFB is the feedback bias
current, nominally -20nA. The minimum
recommended load current of 1
µA forces an
APPLICATIONS HINTS


Similar Part No. - SPX2954AN-3.3

ManufacturerPart #DatasheetDescription
logo
Sipex Corporation
SPX2954AN-3.3 SIPEX-SPX2954AN-3.3 Datasheet
204Kb / 7P
   250 mA Low Drop Out Voltage Regulator
More results

Similar Description - SPX2954AN-3.3

ManufacturerPart #DatasheetDescription
logo
Advanced Monolithic Sys...
AMS2954 ADMOS-AMS2954_08 Datasheet
188Kb / 15P
   250mA LOW DROPOUT VOLTAGE REGULATOR
AMS2954 ADMOS-AMS2954 Datasheet
169Kb / 15P
   250mA LOW DROPOUT VOLTAGE REGULATOR
logo
Sipex Corporation
SPX2954 SIPEX-SPX2954_05 Datasheet
214Kb / 17P
   250mA Low Dropout Voltage Regulator
SPX2954AM3-L-5-0 SIPEX-SPX2954AM3-L-5-0 Datasheet
214Kb / 17P
   250mA Low Dropout Voltage Regulator
logo
Exar Corporation
SPX2954 EXAR-SPX2954 Datasheet
582Kb / 15P
   250mA Low Dropout Voltage Regulator
logo
SHENZHEN FUMAN ELECTRON...
SC662K FUMAN-SC662K Datasheet
966Kb / 3P
   250mA Low Dropout Voltage Regulator IC
SC6207 FUMAN-SC6207 Datasheet
1Mb / 4P
   250mA Low Dropout Voltage Regulator IC
logo
Taiwan Semiconductor Co...
TS9011 TSC-TS9011 Datasheet
60Kb / 4P
   250mA CMOS Low Dropout Voltage Regulator
logo
Micrel Semiconductor
MIC2954 MICREL-MIC2954_07 Datasheet
525Kb / 15P
   250mA Low-Dropout Regulator
logo
Texas Instruments
REG102-25 TI1-REG102-25 Datasheet
961Kb / 25P
[Old version datasheet]   250mA Low-Dropout Regulator
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com