SPX2955S [SIPEX]
暂无描述;
SIPEX CORPORATION 
SPX2955/56/57
350mA Low Drop Out Voltage Regulator
with Shutdown
(PRELIMINARY INFORMATION)
FEATURES
APPLICATIONS
• Output Accuracy 5V, 3.3V@ 350mA Output
• Very Low Quiescent Current
• Battery Powered Systems
• Cordless Telephones
• Low Dropout Voltage
• Radio Control Systems
• Portable/Palm Top/Notebook Computers
• Portable Consumer Equipment
• Portable Instrumentation
• Automotive Electronics
• SMPS Post-Regulator
• Extremely Tight Load And Line Regulation
• Very Low Temperature Coefficient
• Current & Thermal Limiting
• Error Flag Warns Of Output Dropout
• Logic-Controlled Electronic Shutdown
• Output Programmable From 1.24V to 29V
• Voltage Reference
PRODUCT DESCRIPTION
The SPX2955/56/57 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 SPX2955/56/57 features very low quiescent current
(100µA Typ.) and very low dropout voltage. This includes a tight initial tolerance of 1% max and 2% max., and very low output
temperature coefficient, making the SPX2955/56/57 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 SPX2955/56/57 is
offered in 3-pin and 5-pin TO-220 package compatible with other 5 volt and adjustable regulators, in 8-Pin Plastic Dip SO-8 (same pin
out as SPX2951) and surface mount TO-263 packages.
The regulator output voltage (of the 8-pin package and 5-pin TO-220 & TO-263) may be pin-strapped for a 5V and 3.3V or
programmed from 1.24V to 29V with an external pair of resistors. Look for SPX2951 for 150mA and SPX2954 for 250mA
applications.
PIN CONNECTIONS
TO-220-3 Package
TO-263-5 Package
SPX2956/57
TO-220-5 Package
8-Pin Surface Mount
3
2
1
VOUT
GND
VIN
1
2
8
7
OUTPUT
SENSE
INPUT
FEEDBACK
SPX2955
Five Lead Package Pin Functions:
SPX2956/57
3
4
SHUTDOWN
6
5
Front View
5V/ 3.3V TAP
ERROR
SPX2956
SPX2957
ADJUST
SHUTDOWN
GND
GROUND
ERROR
INPUT
GND
1)
2)
3)
4)
5)
TO-263-3 Package
Top View
3
2
1
VOUT
OUTPUT
INPUT
1
2 3 4
5
SPX2955
GND
V IN
SHUTDOWN OUTPUT
1 2 3 4 5
Top View
Top View
Front View
Rev. 11/21/00
SPX2955/56/57
ABSOLUTE MAXIMUM RATINGS
Power Dissipation..........................................Internally Limited
Lead Temp. (Soldering, 5 Seconds) ................................ 260°C
Storage Temperature Range ..............................-65° to +150°C
Operating Junction Temperature Range (Note 9)
Operating Input Supply Voltage....................... 3.0V to +60V
Feedback Input Voltage ..................................-1.5V to +30V
Shutdown Input Voltage..................................-0.3V to +30V
Error Comparator Output................................-0.3V to +30V
ESD Rating ............................................................2KV Min
SPX2955/56/57...................................... -40C° to +125°C
ELECTRICAL CHARACTERISTICS at VS=±15V,TA=25°C, unless otherwise specified.
applies over the full
Boldface
operating temperature range.
PARAMETER
CONDITIONS
Typ.
SPX2955/56/57A
SPX2955/56
UNITS
(Note 2)
Min
Max
Min
Max
3.3V Version
Output Voltage
3.3
3.3
3.267
3.333
3.234
3.185
3.366
3.415
V
3.217
3.382
-40 C T +125 C
°
≤
≤
°
J
1mA ≤IL ≤ 350mA
5V Version
Output Voltage
5.0
5.0
4.950
4.880
5.050
5.120
4.900
4.870
5.100
5.130
V
-40 C T +125 C
°
≤
≤
°
J
1mA ≤IL ≤ 350mA
SPX2955/56/57A
100
SPX2955/56/57
150
All Voltage Options
Output Voltage
20
0.03
0.04
60
ppm/°C
%max
%max
mV
Temperature Coefficient
Line Regulation ( Note 3)
(Note 1)
0.1
0.40
0.20
0.30
100
150
250
300
300
420
400
500
100
150
1
0.20
0.80
0.30
0.50
100
150
250
300
350
420
500
600
100
150
1
6V ≤ VIN ≤30V (Note 4)
Load Regulation ( Note 3 )
IL = 1 to 350mA
IL = 0.1 to 1mA
IL = 1mA
Dropout Voltage
( Note 5 )
IL = 100mA
IL = 250mA
IL = 350mA
IL = 1mA
220
250
375
50
Ground Current
µA
IL = 100mA
IL = 250mA
IL = 350mA
VOUT = 0
0.5
4
mA
2
2
8
8
10
10
5
10
10
15
15
Current Limit
700
800
0.2
700
800
0.2
mA
Thermal Regulation
0.05
400
%/w
Output Noise,
10Hz to 100kHz
IL = 100mA
CL = 2.2µF
CL = 33µF
µV
Vrms
260
Rev. 11/21/00
SPX2955/56/57
(Continued)
Typ.
SPX2955/57A
Min Max
SPX2955/57A
SPX2955/57
Min Max
SPX2955/57B
UNITS
PARAMETER
CONDITIONS
(Note 2)
Typ.
1.235
Adjustable Versions only
Reference Voltage
1.210
1.260
1.270
1.285
1.200
1.270
1.280
1.285
V
1.200
1.185
1.990
1.185
Reference Voltage
Feedback Pin Bias Current
Over Temperature (Note 6)
(Note 7)
V
20
40
60
60
80
NA
Reference Voltage Temperature
Coefficient
ppm/°C
nA/°C
50
Feedback Pin Bias Current
Temperature Coefficient
0.1
Error Comparator
Output Leakage Current
V
0H = 30V
0.01
150
60
1.00
2.00
250
400
1.00
2.00
250
400
µA
mV
mV
mV
mV
Output Low Voltage
Upper Threshold Voltage
Lower Threshold Voltage
Hysteresis
VIN = 4.5V
I
0L = 400µA
(Note 8)
(Note 8)
(Note 8)
40
25
40
25
75
95
140
95
140
15
Shutdown Input
Input logic Voltage
Low (Regulator ON)
High (Regulator OFF)
VS = 2.4V
V
1.3
30
2.0
0.7
50
100
600
750
2.0
0.7
90
Shut down Pin Input Current
µA
150
800
1000
15
VS = 30V
450
3
Regulator Output Current in Shutdown
10
20
µA
25
Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range.
Note 1:
Note 2:
Unless otherwise specified all limits are guaranteed for Tj = 25°C, VIN = 6V, IL = 100µA and CL = 1µF. Additional conditions for the 8-pin versions are
feedback tied to 5V tap and output tied to output sense (VOUT = 5V) and VSHUTDOWN ≤ 0.8V.
Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
Note 3:
covered under the specification for thermal regulation.
: Line regulation for the SPX2955/56/57 is tested at 150°C for I = 1 mA. For I = 100µA and T = 125°C, line regulation is guaranteed by design to 0.2%. See
Note 4
typical performance characteristics for line regulation versus temperature and load curLrent.
L
J
Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V differential at
Note 5:
very low values of programmed output voltage, the minimum input supply voltage of 2V ( 2.3V over temperature) must be taken into account.
V
REF ≤VOUT ≤ (Vin - 1V), 2.3 ≤Vin≤30V, 100µA≤IL≤ 250 mA, TJ ≤ TJMAX
.
Note 6:
Note 7:
Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nominal reference voltage measured at 6V input. To
express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VOUT/VREF = (R1 + R2)/R2. For example, at a programmed output
voltage of 5V, the Error output is guaranteed to go low when the output drops by 95 mV x 5V/1.235 = 384 mV. Thresholds remain constant as a percent of VOUT as
VOUT is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.
V
SHUTDOWN ≥ 2V, VIN ≤ 30V, VOUT =0, Feedback pin tied to 5V Tap.
Note 8:
Note 9:
The junction -to-ambient thermal resistance of the TO-92 package is 180°C/ W with 0.4” leads and 160°C/ W with 0.25” leads to a PC board.
The thermal resistance of the 8-Pin DIP package is 105°C/W junction-to-ambient when soldered directly to a PC board. Junction-to-ambient thermal resistance for the
SOIC (S) package is 160°C/W.
Rev. 11/21/00
SPX2955/56/57
UNREGULATED DC
5V @ 350mA
MAX
1
7
8
+
INPUT
FEEDBACK
OUTPUT
2
SENSE
180k Ω ..
60k Ω ..
+
_
6
ERROR
AMPLIFIER
3
FROM
CMOS OR
TTL
Ω
330k ..
5V TAP
SHUTDOWN
+
5
µ
1
F..
+
+
_
______
60 mV
ERROR
ERROR DETECTION
COMPARATOR
TO CMOS OR
TTL
1.23V
+
4
REFERENCE
GROUND
SPX2955/56/57 Block Diagram
Rev. 11/21/00
SPX2955/56/57
APPLICATION HINTS
This problem can be fixed by adding a 100pF capacitor between
output and feedback and increasing the output capacitor to at least
3.3µF.
EXTERNAL CAPACITORS
The stability of the SPX2955/56/57 requires a 2.2µF or greater
capacitor between output and ground. Oscillation could occur
without this capacitor. Most types of tantalum or aluminum
electrolytic works fine here. For operations of below -25°C solid
tantalum is recommended since the many aluminum types have
electrolytes the 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 capacitor
value can be increased without limit.
ERROR DETECTION COMPARATOR OUTPUT
The Comparator produces
a logic low output whenever the
SPX2955/56/57 output falls out of regulation 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 SPX2955/56/57 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
SPX2955/56/57’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.
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 0.5µF and 0.15µF for 1mA. More
output capacitance needed for the 8-pin version at voltages below
5V since it runs the error amplifier at lower gain. At worst case
5µF or greater must be used for the condition of 250mA load at
1.23V output.
The error comparator has an open-collector output, which requires an
external pull-up resistor. Depending on the system requirements the
resistor 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.
The SPX2955/56/57, unlike other low dropout regulators will
remain stable and in regulation with no load in addition to the
internal voltage divider. This feature is especially important in
application like CMOS RAM keep-alive. When setting the output
voltage of the SPX2955/56/57, a minimum load of 10mA 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 0.1µF
tantalum or aluminum electrolytic capacitor should be placed
from the input to the ground.
PROGRAMMING THE OUTPUT VOLTAGE OF
SPX2955/56/57
The SPX2956/57 may be pin-strapped for 5V using its internal
voltage divider by tying Pin 1 (output) to Pin 2 (sense) and Pin 7
(feedback) to Pin 6 (5V Tap).
Instability can occur if there is stray capacitance to the
SPX2955/56/57 feedback terminal (pin 7). This could cause
more problems when using a higher value of external resistors to
set the output voltage.
+VIN
4.75V
8
100K
O U T PU T
+V
______
ERROR
IN
ERROR
5
V O L TA G E
1.2 to 29V
1
OUTPUT
VOUT
_______
ER R O R *
SPX2955/57
+
3
R1
SHUTDOWN
INPUT
10uF
SD
.01uF
FB
GND
4
7
+
5.0V
+
1.23V
VREF
IN PU T
V O L TA G E
+
1.3V
+
R2
* See A pplication Info.
_______
F igure 1. E R R O R O utput T im ing
Figure 2. Adjustable Regulator
Rev. 11/21/00
SPX2955/56/57
Also, it may be programmed for any output voltage between its
1.235V reference and its 30V maximum rating. As seen in
Figure 2, an external pair of resistors is required.
Refer to the below equation for the programming of the output
voltage::
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 SPX2955/56/57 but is relatively inefficient, as
increasing the capacitor 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 bypass capacitor across R1,
since it reduces the high frequency gain from 4 to unity. Pick
V
OUT = VREF × ( 1 + R1\ R2 )+ IFBR1
The VREF is 1.235 and IFB is the feedback bias current, nominally
-20nA. The minimum recommended load current of 1 µA forces
an upper limit of 1.2 MΩ on value of R2. If no load is presented
the IFB produces an error of typically 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 SPX2955/56/57 typically draws 60 µA at no load with Pin 2
open-circuited this is a small price to pay
C
BYPASS ≅ 1 / 2πR1 × 200 Hz
or choose 0.01µF. When doing this, the output capacitor must be
increased to 3.3µF to maintain stability. These changes reduce the
output noise from 430µV to 100µV Vrms for a 100kHz bandwidth at
5V output. With the bypass capacitor added, noise no longer scales
with output voltage so that improvements are more dramatic at higher
output voltages.
HEAT SINK REQUIREMENTS
Depending on the maximum ambient temperature and maximum
power dissipation a heat sink may be required with the
SPX2955/56/57. The junction temperature range has to be within
the range specified under Absolute Maximum Ratings under all
possible operating conditions. To find out if a heat sink is
required, the maximum power dissipation of the device needs to
be calculated. This is the maximum specific AC voltage that
must be taken into consideration at input. Figure 3 shows the
condition and power dissipation which should be calculated with
the following formula:
Iin
5V
Vin
IN
OUT
IL
P
TOTAL = (VIN - 5) IL + (VIN)IG
SPX2955
LOAD
+
+
Next step is to calculate the temperature rise TR (max). TJ (max)
maximum allowable junction temperature, TA (max) maximum
ambient temperature :
2.2 uF
GND
IG
IIN = IL + IG
TR (max) = TJ (max) - TA (max)
Junction to ambient thermal resistance θ(j-A) can be calculated
after determining of PTOTAL & TR (max):
Figure 3. 5V Regulator Circuit
θ(J-A) = TR (max)/P(max)
If the θ(J-A) is 60°C/W or higher, the device could be operated
without a heat sink. If the value is below 60°C/W then the heat
sink is required and the thermal resistance of the heat sink can be
calculated by the following formula, θ(J-C) junction to case, θ(C-H)
case to heat sink, θ(H-A) heat sink to ambient:
θ(J-A) = θ(J-C) + θ(C-H) + θ(H-A)
Rev. 11/21/00
SPX2955/56/57
TYPICAL APPLICATIONS
+VIN
8
+VIN
______
ERROR
ERROR
5
*VOUT = VIN
1
OUTPUT
VOUT
SPX2955/57
3
SHUTDOWN
INPUT
SD
FB
GND
4
7
*MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 4mV TO 400mV.
DEPENDING ON LOAD CURRENT. CURRENT LIMIT IS TYPICALLY 160mA
Wide Input Voltage Range Current
+VIN
+VIN
*VOUT = 5V
VOUT
SPX2955
+
10uF
GND
4
SPX2955 FIXED +5V REGULATOR
Rev. 11/21/00
SPX2955/56/57
ORDERING INFORMATION
Precision Output Voltage
Ordering No.
SPX2955U3
Packages
2%
2%
2%
1%
1%
1%
2%
2%
2%
1%
1%
1%
2%
2%
2%
1%
1%
1%
2%
2%
2%
1%
1%
1%
2%
2%
2%
1%
1%
1%
1%
1%
2%
2%
1%
1%
2%
2%
1%
1%
2%
2%
Adj
3.3V
5.0V
Adj
3 Lead TO-220
3 Lead TO-220
3 Lead TO-220
3 Lead TO-220
3 Lead TO-220
3 Lead TO-220
5 Lead TO-220
5 Lead TO-220
5 Lead TO-220
5 Lead TO-220
5 Lead TO-220
5 Lead TO-220
3 Lead TO-263
3 Lead TO-263
3 Lead TO-263
3 Lead TO-263
3 Lead TO-263
3 Lead TO-263
5 Lead TO-263
5 Lead TO-263
5 Lead TO-263
5 Lead TO-263
5 Lead TO-263
5 Lead TO-263
8 Lead SOIC
SPX2955U3-3.3
SPX2955U3-5.0
SPX2955AU3
3.3V
5.0V
Adj
SPX2955AU3-3.3
SPX2955AU3-5.0
SPX2955U5
3.3V
5.0V
Adj
SPX2955U5-3.3
SPX2955U5-5.0
SPX2955AU5
3.3V
5.0V
Adj
SPX2955AU5-3.3
SPX2955AU5-5.0
SPX2955T3
3.3V
5.0V
Adj
SPX2955T3-3.3
SPX2955T3-5.0
SPX2955AT3
3.3V
5.0V
Adj
SPX2955AT3-3.3
SPX2955AT3-5.0
SPX2955T5
3.3V
5.0V
Adj
SPX2955T5-3.3
SPX2955T5-5.0
SPX2955AT5
3.3V
5.0V
Adj
SPX2955AT5-3.3
SPX2955AT5-5.0
SPX2955S
3.3V
5.0V
Adj
8 Lead SOIC
SPX2955S-3.3
SPX2955S-5.0
SPX2955AS
8 Lead SOIC
8 Lead SOIC
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
8 Lead SOIC
SPX2955AS-3.3
SPX2955AS-5.0
SPX2955AS-3.3
SPX2955AS-5.0
SPX2956U3-3.3
SPX2956U3-5.0
SPX2956AU3-3.3
SPX2956AU3-5.0
SPX2956U5-3.3
SPX2956U5-5.0
SPX2956AU5-3.3
SPX2956AU5-5.0
SPX2956T3-3.3
SPX2956T3-5.0
8 Lead SOIC
8 Lead SOIC
8 Lead SOIC
3 Lead TO-220
3 Lead TO-220
3 Lead TO-220
3 Lead TO-220
5 Lead TO-220
5 Lead TO-220
5 Lead TO-220
5 Lead TO-220
3 Lead TO-263
3 Lead TO-263
Rev. 11/21/00
SPX2955/56/57
ORDERING INFORMATION
Precision Output Voltage
Ordering No.
SPX2956AT3-3.3
SPX2956AT3-5.0
SPX2956T5-3.3
SPX2956T5-5.0
SPX2956AT5-3.3
SPX2956AT5-5.0
SPX2956S-3.3
SPX2956S-5.0
SPX2957U3
Packages
1%
1%
2%
2%
1%
1%
2%
2%
2%
1%
2%
1%
2%
1%
2%
1%
2%
1%
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
3.3V
5.0V
Adj
3 Lead TO-263
3 Lead TO-263
5 Lead TO-263
5 Lead TO-263
5 Lead TO-263
5 Lead TO-263
8 Lead SOIC
8 Lead SOIC
3 Lead TO-220
3 Lead TO-220
5 Lead TO-220
5 Lead TO-220
3 Lead TO-263
3 Lead TO-263
5 Lead TO-263
5 Lead TO-263
8 Lead SOIC
Adj
SPX2957AU3
SPX2957U5
Adj
Adj
SPX2957AU5
SPX2957T3
Adj
Adj
SPX2957AT3
SPX2957T5
Adj
Adj
SPX2957AT5
SPX2957S
Adj
Adj
8 Lead SOIC
SPX2957AS
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation
Headquarters and Main Offices:
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 935-7600
FAX: (408) 934-7500
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described
hereing; neither does it convey any license under its patent rights nor the rights of others.
Rev. 11/21/00
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