The SPX2945/46/47 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 SPX2945/46/47 features very low quiescent current
(100µA Typ.) and very low dropout voltage. This includes a tight initial tolerance of 1% max and very low output temperature
coefficient, making the SPX2945/46/47 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 SPX2945/46/47 is
offered in 3-pin and 5-pin TO-220 package, SO-8 (same pin out as SPX2951), SOT-223, and surface mount TO-263 packages.
The regulator output voltage (of the 8-pin SO-8 and 5-pin TO-220 & TO-263) may be pin-strapped for a 3.3V and 5.0V or
programmed from 1.24V to 29V with an external pair of resistors. Look for SPX2951 for 150mA, SPX2954 for 250mA and SPX2955
for 350mA applications.
APPLICATIONS
Battery Powered Systems
•
Cordless Telephones
•
Radio Control Systems
•
Portable/Palm Top/Notebook Computers
•
Portable Consumer Equipment
•
Portable Instrumentation
•
Automotive Electronics
•
SMPS Post-Regulator
•
Voltage Reference
•
TO-263-5 (T)
SPX2946/47
12
45
3
Top View
Five Lead Package Pin Functions:
SPX2946
1) ERROR
2) V
3) GND
4) V
5) SHUTDOWN
SPX2947
1) ERROR
2) SHUTDOWN
IN
3) GND
4) V
5) V
IN
OUT
OUT
TO-220-5 (U)
SPX2946/47
4321
Front View
5
PIN CONNECTIONS
TO-220-3 (U)
SPX2945
123
V
V
GND
IN
Front View
TO-263-3 (T)
SPX2945
1
3
2
GND
V
V
IN
OUT
OUT
Top View
TO-252 (R)
SPX2945
1
23
GND
V
IN
Top View
8-Pin Surface Mount (S)
V
OUT
SENSE
SHUTDOWN
V
GND
OUT
1
2
SPX2945
3
4
Top View
8
V
IN
7
FEEDBACK
6
5V/ 3.3V TAP
5
ERROR
SOT-223 (M3)
SPX2945
132
V
IN
GND
Top View
V
OUT
Rev. 10/25/00
Page 2
SPX2945/46/47
ABSOLUTE MAXIMUM RATINGS
Power Dissipation..........................................Internally Limited Input Supply Voltage .....................................+3.0V to +60V
Lead Temp. (Soldering, 5 Seconds) ................................ 260°C Feedback Input Voltage ..................................-1.5V to +30V
Storage Temperature Range ..............................-65° to +150°C Shutdown Input Voltage..................................-0.3V to +30V
Operating Junction Temperature Range (Note 9) Error Comparator Output................................-0.3V to +30V
SPX2945/46/47...................................... -40C° to +125°C ESD Rating ............................................................2KV Min
ESD Rating ................................................................ 2KV Min
Output Voltage
Temperature Coefficient
Line Regulation ( Note 3)
Load Regulation ( Note 3 ) IL = 1 to 500mA
Dropout Voltage
( Note 5 )
Ground Current I
Current Limit
Thermal Regulation 0.05 0.2 %/w
Output Noise, 10Hz to 100kHz
I
= 100mA
L
Adjustable Versions only
Reference Voltage 1.235 1.210
Reference Voltage Over Temperature (Note 6) 1.185 1.285 V
Feedback Pin Bias Current 20 40
Reference Voltage Temperature
Coefficient
Feedback Pin Bias Current
Temperature Coefficient
CONDITIONS
(Note 2)
1mA ≤I
1mA ≤I
500mA
≤
L
500mA
≤
L
(Note 1)
6V ≤ V
I
L
I
L
I
L
L
I
L
I
L
I
L
V
C
C
≤30V (Note 4)
IN
= 0.1 to 1mA
= 1mA
= 500mA
= 1mA
= 150mA
= 300mA
= 500mA
= 0 700
OUT
= 2.2µF
L
= 33µF
L
(Note 7) 50 ppm/°C
0.1 nA/°C
±15V,TA=25°C, unless otherwise specified.
Typ.
3.3
3.3
5.0
5.0
20
0.03 0.1
0.04 0.20
60
350
50
0.5
4
5
400
260
Typ SPX2945/47
SPX2945/46
Min Max
3.267
3.217
4.950
4.880
100
100
1.200
Boldface
3.333
3.382
5.050
5.120
100
0.40
0.30
150
400
500
150
1
2
8
10
10
15
800
1.260
1.270
60
applies over the
UNITS
V
V
ppm/°C
%max
%max
mV
A
µ
mA
mA
V Vrms
µ
V
nA
Rev. 10/25/00
Page 3
SPX2945/46/47
(Continued)
Output Leakage Current V
Output Low Voltage VIN = 4.5V
Upper Threshold Voltage (Note 8) 60 40
Lower Threshold Voltage (Note 8) 75 95
PARAMETER CONDITIONS
(Note 2)
= 30V 0.01 1.00
0H
I0L = 400µA
Typ.
150 250
SPX2945/46/47
Min Max
25
UNITS
A
µ
2.00
mV
400
mV
mV
140
Hysteresis (Note 8) 15 mV
Input logic Voltage Low (Regulator ON)
High (Regulator OFF)
Shut down Pin Input Current VS = 2.4V
V
= 30V
S
Regulator Output Current in Shutdown 3 10
Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range.
Note 1:
Unless otherwise specified all limits are guaranteed for T
Note 2:
feedback tied to 5V tap and output tied to output sense (V
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 SPX2945/46/47 is tested at 150°C for I
Note 4
typical performance characteristics for line regulation versus temperature and load current.
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
Note 6:
Note 7:
express these thresholds in terms of output voltage change, multiply by the error amplifier gain = V
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 V
V
Note 8:
Note 9:
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.
REF
Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nominal reference voltage measured at 6V input. To
is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.
OUT
V
SHUTDOWN
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.
≤ (Vin - 1V), 2.3 ≤Vin≤30V, 100µA≤I
V
≤
OUT
≥ 2V, VIN ≤ 30V, V
=0, Feedback pin tied to 5V Tap.
OUT
= 25°C, VIN = 6V, IL = 100µA and CL = 1µF. Additional conditions for the 8-pin versions are
j
= 5V) and V
OUT
250 mA, T
≤
L
SHUTDOWN
= 1 mA. For IL = 100µA and TJ = 125°C, line regulation is guaranteed by design to 0.2%. See
L
J
≤ 0.8V.
.
T
≤
JMAX
1.3
30
450
2.0
0.7
50
100
600
750
20
= (R1 + R2)/R2. For example, at a programmed output
OUT/VREF
V
A
µ
A
µ
as
OUT
FROM
CMOS OR
TTL
UNREGULATED DC
+
SHUTDOWN
7
3
FEEDBACK
8
INPUT
+
_
ERROR
AMPLIFIER
+
+
60 mV
+
_
1.23V
REFERENCE
ERROR DETECTION
COMPARATOR
SPX2945/46/47 Block Diagram
1
OUTPUT
Ω
180k
Ω
60k
5V @ 500mA
MAX
2
SENSE
..
..
6
5V TAP
5
______
ERROR
4
GROUND
Ω
..
330k
+
1µF
TO CMOS OR
TTL
Rev. 10/25/00
Page 4
APPLICATION HINTS
EXTERNAL CAPACITORS
The stability of the SPX2945/46/47 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.
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 SPX2945/46/47, 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 SPX2945/46/47, 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.
Instability can occur if there is stray capacitance to the
SPX2945/46/47 feedback terminal (pin 7). This could cause
more problems when using a higher value of external resistors to
set the output voltage.
OUTPUT
VOLTAGE
_______
ERROR*
INP UT
VOLTAGE1.3V
* See App lication Info.
4.75V
+
5.0V
+
Figure 1. ERROR Output Timing
+
+
_______
SPX2945/46/47
This problem can be fixed by adding a 100pF capacitor between
output and feedback and increasing the output capacitor to at least
3.3µF.
ERROR DETECTION COMPARATOR OUTPUT
The Comparator produces a logic low output whenever the
SPX2945/46/47 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 SPX2945/46/47 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
SPX2945/46/47’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 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.
PROGRAMMING THE OUTPUT VOLTAGE OF
SPX2945/46/47
The SPX2945/46/47 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).
100K
ERROR
OUTPUT
SHUTDOWN
INPUT
5
3
Figure 2. Adjustable Regulator
______
ERROR
SD
SPX2945
GND
4
+V
IN
8
+V
IN
V
OUT
1.2 to 29V
1
R
FB
7
1.23V
V
R
REF
+
1
2
.01uF
10uF
Rev. 10/25/00
Page 5
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::
V
OUT
= V
× ( 1 + R1/ R2 )+ IFBR
REF
1
The V
is 1.235 and IFB is the feedback bias current, nominally
REF
-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 I
produces an error of typically 2% in V
FB
eliminated at room temperature by trimming R
, which may be
OUT
. To improve the
1
accuracy choose the value of R2 = 100k this reduces the error by
0.17% and increases the resistor program current by 12µA. Since
the SPX2945/46/47 typically draws 60 µA at no load with Pin 2
open-circuited this is a small price to pay
(max):
+
θ
θ
(j-A)
(max)
junction to case,
θ
(J-C)
+
θ
(C-H)
G
(max). TJ (max)
R
(max) maximum
A
can be calculated
(H-A)
θ
(C-H)
HEAT SINK REQUIREMENTS
Depending on the maximum ambient temperature and maximum
power dissipation a heat sink may be required with the
SPX2945/46/47. 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:
P
= (VIN - 5) IL + (VIN)I
TOTAL
Next step is to calculate the temperature rise T
maximum allowable junction temperature, T
ambient temperature :
T
(max) = TJ (max) - TA (max)
R
Junction to ambient thermal resistance
after determining of P
If the
is 60°C/W or higher, the device could be operated
θ
(J-A)
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,
case to heat sink,
TOTAL & TR
= TR (max)/P
θ
(J-A)
heat sink to ambient:
θ
(H-A)
=
θ
θ
(J-A)
(J-C)
SPX2945/46/47
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 SPX2945/46/47 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 R
,
1
since it reduces the high frequency gain from 4 to unity. Pick
C
BYPASS
1 / 2πR
≅
× 200 Hz
1
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.
I
V
in
in
+
I
= I
+ I
IN
L
G
IN
SPX2945
GND
I
G
OUT
Figure3 5V Regulator Circuit
+
5V
2.2 uF
I
L
LOAD
Rev. 10/25/00
Page 6
TYPICAL APPLICATIONS
+V
IN
8
+V
ERROR
OUTPUT
5
______
ERROR
IN
1
V
OUT
*V
SPX2945
SHUTDOWN
INPUT
*MINIMUM INPUT-OUTPUT VOLTAGE RANGES FROM 4mV TO 400mV.
DEPENDING ON LOAD CURRENT. CURRENT LIMIT IS TYPICALLY 500mA
3
SD
GND
4
FB
7
Wide Input Voltage Range Current
SPX2945
GND
4
+V
IN
+V
IN
*V
= 5V
OUT
+
10uF
V
OUT
SPX2945/46/47
= V
OUT
IN
SPX2945 FIXED +5V REGULATOR
Rev. 10/25/00
Page 7
SPX2945/46/47
PACKAGE DRAWING
TO-263-3L (T)
±
±
(4.470
0.005
(10.287 0.127)
0.405
±
±
0.005
0.055 (1.397)
0.176
0.050
±
0.002
(1.270
±
0.356 0.005
±
(9.042 0.127)
0.600
(15.24
+
0.025
-
±
0.635)
0.103 BSC
(2.616)
0.050 (1.270)
+
0.032
0.001
+
(0.813 0.025)
-
0.015
(0.381 0.074)
+
+
-
0° 8°
0.003
±
0.010
0.100
±
(2.540 0.254)
0.127)
±
0.051)
Rev. 10/25/00
Page 8
SPX2945/46/47
PACKAGE DRAWING
TO-263-5L (T)
0.4050.005
(10.287 ±
±
0.127)
±
0.067
(1.7020.127)
0.005
±
0.055 (1.397)
±
0.3560.005
±
(9.042
0.0320.003
(0.813
0.127)
0.6000.025
(15.24
±
±
0.076)
±
±
0.635)
0°
±
0.0150.003
±
(0.381
0.074)
8°
0.1760.005±(4.470 0.127)
±
0.0500.002
±
0.1000.010
±
(2.5400.254)
(1.270 0.051)
±
±
Rev. 10/25/00
Page 9
SPX2945/46/47
PACKAGE DRAWING
TO-220-3L (U)
0.110 ± 0.010
(2.794 ± 0.254)
0.408 ± 0.013
(10.36 ± 0.33)
0.151D ± 0.002
(3.835 D ± 0.051)
0.250 ± 0.010
(6.350 ± 0.254)
0.340 ± 0.010
(8.636 ± 0.254)
0.540 ± 0.015
(13.720 ± 0.381)
0.150 MIN
(3.81 MIN)
0.410
(10.41)
0.180 ± 0.005
(4.572 ± 0.127)
7o Typ.
0.050 ± 0.002
(1.270 ± 0.051)
SEATING PLANE
1.020 ± 0.015
(25.910 ± 0.381)
Tapered 1
2 Sides
o
0.050 TYP
(1.27 TYP)
0.200 ± 0.010
(5.080 ± 0.254)
0.100 ± 0.010
(2.540 ± 0.254)
0.032 ± 0.005
(0.813 ± 0.127)
0.015 ± 0.010/-0.015
(2.667± 0.254/-0.381)
0.015 ± 0.010/-0.002
(0.381± 0.254/-0.051)
Rev. 10/25/00
Page 10
SPX2945/46/47
PACKAGE DRAWING
TO-220-5L (T)
+
0.150 D
0.005
+
0.400
0.005
+
0.108
0.005
(2.74
-
+
2.74)
-
(10.16
+
-
-
0.13)
+
0.067
0.005
+
(1.70
0.127)
-
0.268 REF
(6.81 REF)
(3.81D
0.590
(14.99
0.547
(13.89
0.032
(0.81
0.268 REF
-
+
-
0.13)
+
+
-
+
+
-
0.250
(6.35
+
0.005
+
0.13)
-
0.005
0.005)
0.005
0.13)
+
+
-
-
0.005
0.13)
0.175
(4.45
7°
Typ.
0.015
(0.38
+
+
+
+
-
-
0.005
0.13)
0.005
0.13)
0.050
(1.27
1.137 REF
(28.88 REF)
+
0.105
+
(2.67
-
+
0.005
-
+
0.13)
-
SEATING
PLANE
0.005
0.13)
Rev. 10/25/00
Page 11
SPX2945/46/47
PACKAGE DRAWING
TO-252-3L (R)
E
b
2
-A-
L
2
A
A
1
C
1
4
D
3
21
L
3
L
1
-C-
M
b
3 PLCS
A M
C
e1
D
1
.010
TERM 4
b
1
e
NOTES
1. Refer To Applicable Symbol List.
2. Dimensions And Tolerancing Per Ansi Y14.5m - 1982.
3. Lead Dimension Uncontrolled in L
E
1
4. Tab Contour Optional Within Dim. b
5. D1 & E1 Establishes A Minimum Mounting Surface for Terminal 4.
6. L is the Termal Length for Soldering.
7. Controlling Dimension: Inch
8. 2 Mils Suggested For Postive Contact At Mounting.
5.0V 5 Lead TO-220
Adj 3 Lead TO-223
Adj 3 Lead TO-263
Adj 5 Lead TO-263
Adj 3 Lead TO-220
Adj 5 Lead TO-220
Rev. 10/25/00
Page 15
SPX2945/46/47
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. 10/25/00
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