SPX2945T3-3.3 [SIPEX]
500mA Low Drop Out Voltage Regulator with Shutdown; 500毫安低压降稳压器，带有关断
| 型号： | SPX2945T3-3.3 |
| 厂家： | 
SIPEX CORPORATION |
| 描述： | 500mA Low Drop Out Voltage Regulator with Shutdown |
| 文件： | 总11页 (文件大小：101K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
SPX2945
400mA Low Dropout Voltage Regulator with Shutdown
FEATURES
1.2V to 20V
1
7
8
+VIN
+VIN
VOUT
+
■ Output 3.3V, 5.0V at 400mA Output
■ Very Low Quiescent Current, 100µA
■ Low Dropout Voltage, 420mV at 400mA
■ Extremely Tight Load and Line Regulation
■ Very Low Temperature Coefficient
■ Current & Thermal Limiting
100K
OFF
0.01µF
10µF
R1
FB
SPX2945
______
ERROR
SHUTDOWN
INPUT
ERROR
SD
3
5
OUTPUT
GND
4
VREF
R2
ON
Adjustable Regulator
■ Error Flag Warns Of Output Dropout
■ Logic-Controlled Electronic Shutdown
5V
VIN
IN
OUT
■ Output Programmable From 1.24V to 20V
(for SO-8)
SPX2945
+
+
2.2 µF
GND
0.1 µF
5V Regulator Circuit
DESCRIPTION
TheSPX2945isalowpowervoltageregulator.Thisdeviceisanexcellentchoiceforuseinbattery-powered
applications such as cordless telephones, radio control systems, and portable computers. The SPX2945
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 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 is offered in 3-pin TO-220 package, SO-8 (same pin
out as SPX2951), SOT-223, surface mount 3-Pin TO-252, 3-Pin TO-263 packages and 5-Pin TO-263.
The regulator output voltage (of the 8-pin SO-8) may be pin-strapped for a 3.3V and 5.0V or programmed
from1.24Vto20Vwithanexternalpairofresistors. LookforSPX2951for150mAandSPX2954for250mA
applications.
TO-252 (R)
TO-263-5 (T5)
8-Pin Surface Mount
SOT-223 (M3)
(S)
TO-220-3 (U)
TO-263-3 (T)
VOU
1
8
7
VIN
SPX2945
SPX2945
SPX2945
2
SPX2945
5 Pin TO-263
SPX2945
SENS
SHUTDOWN
GN
FEEDBACK
5V/ 3.3V TAP
ERRO
SPX2945
1
2
3
1
2
3
1
3
2
3
4
6
5
1
2
3
1
2 3 4 5
VIN
VOU
GN
VIN GN VOU
VIN GN
VOU
VIN GN VOU
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
Power Dissipation ........................................................ Internally Limited
Lead Temp. (Soldering, 5 Seconds) ............................................. 260°C
Storage Temperature Range ........................................ -65°C to +150°C
Operating Junction Temperature Range ....................... -40°C to +125°C
Input Supply Voltage ......................................................... -20V to +26V
Feedback Input Voltage ................................................ -1.5V to +26V
Shutdown Input Voltage ................................................ -0.3V to +26V
Error Comparator Output .............................................. -0.3V to +26V
ESD Rating ............................................................................ 2kV Min
ELECTRICAL CHARACTERISTICS
Electrical characteristics at VIN = VO+1V, IO = 1mA, COUT = 2.2µF, TA = 25°C, unless otherwise specified. The ♦ denotes
the specifications wich apply over full operating tempeture range -40°C to +85°C, unless noted.
PARAMETER
CONDITIONS
(Note 2)
MIN
TYP
MAX
UNITS
3.3V Version
Output Voltage
3.267
3.217
3.3
3.3
3.333
3.382
V
1mA ≤ IL ≤ 400mA
1mA ≤ IL ≤ 400mA
♦
♦
5.0V Version
Output Voltage
4.950
4.880
5.0
5.0
5.050
5.120
V
All Voltage Options
Output Voltage
20
100
20
♦
ppm/°C
Temperature Coefficient
(Note1)
Line Regulation (Note 3)
Load Regulation (Note 3)
6V ≤ VIN ≤ 20V (Note 4)
IL=1 to 400mA
1.5
6
♦
♦
mV
mV
20
30
Dropout Voltage (Note5)
IL=1mA
60
100
150
450
700
mV
♦
♦
IL=400mA
360
Ground Current
IL=1mA
100
2
200
300
4
µA
♦
♦
♦
IL=150mA
IL=300mA
IL=400mA
mA
6
4
8
12
15
25
8
♦
♦
Current Limit
VOUT=0
330
800
0.2
mA
Thermal Regulation
0.05
%/W
Output Noise, 10Hz to 100kHz, CL=2.2µF
400
260
µVRMS
IL=100mA
CL=33µF
PSRR at 100KHz
IL=100mA
31
dB
CL=10µF
Adjustable 8 Pin Version only
Reference Voltage
1.210
1.185
1.235
1.260
1.285
V
V
Reference Voltage
Over Temperature
Feedback Pin Bias Current
20
20
40
60
nA
♦
Reference Voltage Temp.
Coefficient
ppm/°C
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
2
ELECTRICAL CHARACTERISTICS: Continued
Electrical characteristics at VIN = VO+1V, IO = 1mA, COUT = 2.2µF, TA = 25°C, unless otherwise specified. ♦ applies over the
full operating temperature range.
PARAMETER
CONDITIONS
(Note 2)
MIN
TYP
0.1
0.01
150
60
MAX
♦
UNITS
nA/°C
µA
Feedback Pin Bieas Current
Temperature Coefficient
Output Leakage Current
V0H=20V
1
2
♦
Output Low Voltage
VIN=4.5V
250
400
mV
I0L=400µA
♦
Upper Threshold Voltage
Lower Threshold Voltage
(Note 6)
(Note 6)
(Note 6)
40
25
mV
75
95
mV
140
♦
Hysteresis
15
mV
V
Input Logic Voltage
Low (Regulator ON)
High (Regulator OFF)
0.7
2.0
♦
♦
1.3
30
Shutdown Pin Input Current
VS=2.4V
50
µA
100
600
750
♦
♦
VS=26V
450
3
Regulator Output Current
in Shutdown
(Note 7)
10
20
µA
♦
Note 1: Output or reference voltage temperature coefficients defined as the worst case voltage change divided by
the total temperature range.
Note2: UnlessotherwisespecifiedalllimitsareguaranteedforTj =25°C,VIN =6V,IL =1mAandCL =2.2µF. Additional
conditions for the 8-pin versions are feedback tied to 5V/3.3V tap and output tied to output sense (VOUT = 5V) and
V
SHUTDOWN ≤ 0.8V.
Note3: Regulationismeasuredatconstantjunctiontemperature, usingpulsetestingwithalowdutycycle. Changes
in output voltage due to heating effects are covered under the specification for thermal regulation.
Note 4: Line regulation for the SPX2945 is tested at 150°C for IL = 1 mA. For TJ = 125°C, line regulation is guaranteed
by design.
Note 5: 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 very low values of programmed output voltage, the minimum input
supply voltage of 2V ( 2.3V over temperature) must be taken into account.
Note 6: 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
constantasapercentofVOUT asVOUT isvaried,withthedropoutwarningoccurringattypically5%belownominal,7.5%
guaranteed.
Note 7: VSHUTDOWN ≥ 2V, VIN ≤ 26V, VOUT = 0, Feedback pin tied to 5V/3.3V Tap.
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
3
SPX2945 - 5.0V BLOCK DIAGRAM
UNREGULATED DC
5V at 400mA
MAX
1
7
8
+
FEEDBACK
OUTPUT
INPUT
2
SENSE
.
180kΩ
6
+
_
ERROR
AMPLIFIER
3
FROM
CMOS OR
TTL
5V TAP
330kΩ .
SHUTDOWN
+
60kΩ .
5
+
1µF
+
_
______
ERROR
60 mV
ERROR DETECTION
COMPARATOR
TO CMOS OR
TTL
1.23V
+
4
REFERENCE
GROUND
APPLICATION INFORMATION
External Capacitors
The SPX2945, unlike other low dropout regu-
lators will remain stable and in regulation with
no load in addition to the internal voltage di-
vider. This feature is especially important in
applications like CMOS RAM keep-alive.
The stability of the SPX2945 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 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 capaci-
tor. The capacitor value can be increased with-
out limit.
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 tanta-
lum or aluminum electrolytic capacitor should
be placed from the input to the ground.
Instability can occur if there is stray capaci-
tancetotheSPX2945feedbackterminal(pin7).
This could cause more problems when using a
higher value of external resistors to set the
output voltage.
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
4.7µF or greater must be used for the condition
of 250mA load at 1.23V output.
This problem can be fixed by adding a 100pF
capacitor between output and feedback and
increasingtheoutputcapacitortoatleast3.3µF.
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
4
Error Detection Comparator Output
2% in V , which may be eliminated at room
temperatOuUrTe by trimming R1. To improve the
accuracy choose the value of R = 100k; this
reduces the error by 0.17% and2 increases the
resistor program current by 12µA. Since the
SPX2945 typically draws 60 µA at no load with
Pin 2 open-circuited this is a small price to pay.
The Comparator produces a logic low output
whenever the SPX2945 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
andtheregulatoroutputvoltageastheSPX2945
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’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.
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 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 bypass capacitor across
R , sinceitreducesthehighfrequencygainfrom
4 1to unity. Pick
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.
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.
Programming the Output Voltage of
SPX2945
The SPX2945 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 in Figure 2, an
external pair of resistors is required.
4.75V
OUTPUT
VOLTAGE
Refer to the below equation for the program-
ming of the output voltage::
_______
ERROR*
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 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
+
+
5.0V
INPUT
VOLTAGE
+
1.3V
+
* See Application Info.
Figure 1. ERROR Output Timing
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
5
PACKAGE: 3 PIN TO-252
-A-
L2
-B-
E
A
A1
C1
b2
A
4
2
SEATING
PLANE
D
L3
L1
H
3
1
L
-C-
b1
c
A
3 PLCS
e
8
.010
M
A
M
C
e1
D1
NOTES
1. Refer To Applicable Symbol List.
2. Dimensions And Tolerancing Per Ansi Y14.5m - 1982.
3. Lead Dimension Uncontrolled in L
3
4. Tab Contour Optional Within Dim. b & L And E & D
2
2
1
1
E1
TERM 4
5. D & E Establishes A Minimum Mounting Surface for
1 1
Terminal 4.
6. L is the Termal Length for Soldering.
7. Controlling Dimension: Inch
8. 2 Mils Suggested For Postive Contact At Mounting.
S
Y
M
B
O
L
N
O
T
INCHES
MM
BACK VIEW A-A
MIN.
MAX
MAX
MIN.
E
0.086
0.035
0.025
0.300
0.205
0.018
0.018
0.235
0.170
0.250
0.170
2.184
0.889
0.635
7.620
5.207
0.457
0.457
5.969
4.318
6.350
4.318
2.3876
1.143
0.889
1.143
5.461
0.5842
0.5842
6.223
-
A
A1
b
b1
b2
c
c1
D
D1
E
E1
e
e1
H
L
0.094
0.045
0.035
0.045
0.215
0.023
0.023
0.245
-
4
4,5
4,5
6.731
-
0.265
-
0.098
0.180
2.489
4.572
0.370
0.020
0.025
0.035
0.045
9.398
0.508
0.635
0.889
1.143
10.414
-
1.016
1.270
1.524
0.410
-
0.040
0.050
0.060
6
L1
L2
L3
4
3
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
6
PACKAGE: 3 PIN TO-220
0.180 ± 0.005
(4.572 ± 0.127)
0.151D ± 0.002
(3.835 D ± 0.051)
0.408 ± 0.013
(10.36 ± 0.33)
0.050 ± 0.002
(1.270 ± 0.051)
0.110 ± 0.010
(2.794 ± 0.254)
0.250 ± 0.010
(6.350 ± 0.254)
Tapered 1°
2 Sides
0.340 ± 0.010
(8.636 ± 0.254)
SEATING
PLANE
1.020 ± 0.015
(25.910 ± 0.381)
0.150 MIN
(3.81 MIN)
Typ.
7°
0.540 ± 0.015
(13.720 ± 0.381)
0.410
(10.41)
0.050 TYP
(1.27 TYP)
0.200 ± 0.010
0.015 ± 0.010/-0.015
(2.667± 0.254/-0.381)
0.100 ± 0.010
(2.540 ± 0.254)
0.015 ± 0.010/-0.002
(0.381± 0.254/-0.051)
(5.080 ± 0.254)
0.032 ± 0.005
(0.813 ± 0.127)
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
7
PACKAGE: 5 PIN TO-263
0.055 (1.397)
0.176 0.005 (4.470 0.127)
0.050 0.002 (1.270 0.051)
0.405
0.005
0.127)
(10.287
0.356 0.005
(9.042
0.127)
0.600
0.025
(15.24
0.635)
0.100
0.010
(2.540 0.254)
+
-
-
0.015
(0.381
0.003
0.074)
+
0.032
0.003
(0.813
0.076)
0.067
0.005
0° 8°
(1.702
0.127)
PACKAGE: 3 PIN TO-263
0.127)
0.051)
0.055 (1.397)
(4.470
0.005
0.176
0.050
0.405
(10.287 0.127)
0.005
0.002 (1.270
0.356 0.005
(9.042 0.127)
0.600 0.025
(15.24
0.635)
0.100 0.010
0.254)
(2.540
+
-
0.003
0.015
0.050 (1.270)
0.032 +- 0.001
(0.813 +- 0.025)
0.103 BSC
(2.616)
+
(0.381 0.074)
-
0°
8°
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
8
PACKAGE: 3 PIN SOT-223
0.124
0.116
0.146
0.295
0.130 0.264
0.041
0.033
0.0905 NOM
0.181 NOM
0.067
0.028
16°C
10°C
0.264
0.248
0.0040
0.0008
0.014
0.010
10°C Max
16°C
10°C
0.033
0.025
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
9
PACKAGE: 8 PIN NSOIC
D
e
E/2
E1
E
E1/2
SEE VIEW C
1
b
INDEX AREA
(D/2 X E1/2)
Ø1
A
TOP VIEW
b
WITH PLATING
Gauge Plane
L2
Ø
Ø1
Seating Plane
L
L1
c
VIEW C
BASE METAL
DIMENSIONS
Minimum/Maximum
(mm)
8 Pin NSOIC
(JEDEC MS-012,
AA - VARIATION)
CONTACT AREA
COMMON HEIGHT DIMENSION
SYMBOL
MIN NOM MAX
1.75
0.25
1.65
0.51
0.25
-
-
-
-
-
A
1.35
A1
A2
b
0.10
1.25
0.31
A2
A
SEATING PLANE
c
0.17
D
E
E1
e
A1
4.90 BSC
6.00 BSC
3.90 BSC
1.27 BSC
SIDE VIEW
L
-
0.40
1.27
L1
L2
1.04 REF
0.25 BSC
-
-
0º
5º
8º
Ø
Ø1
15º
8 PIN NSOIC
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
10
ORDERING INFORMATION
Ordering No.
Top Mark
Accuracy
Output Voltage
Packages
2945M3
33YYWW
3-Pin SOT-223
3-Pin SOT-223
8-Pin SOIC
SPX2945M3-3.3
SPX2945M3-5.0
SPX2945S-3.3
SPX2945S-5.0
1%
1%
1%
1%
3.3V
5.0V
3.3V
5.0V
2945M3
50YYWW
2945S33
33YYWW
SPX2945R
50YYWW
8-Pin SOIC
SPX2945R
504YYWW
3-Pin TO-252
3-Pin TO-252
3-Pin TO-263
3-Pin TO-263
5-Pin TO-263
SPX2945R-3.3
SPX2945R-5.0
SPX2945T-3.3
SPX2945T-5.0
SPX2945T5-3.3
1%
1%
1%
1%
1%
3.3V
5.0V
3.3V
5.0V
3.3V
SPX2945R
YYWW
SPX2945T
33YYWW
SPX2945T5
50YYWW
SPX2945T5
33YYWW
SPX2945T
50YYWW
5-Pin TO-263
3-Pin TO-220
SPX2945T5-5.0
SPX2945U-3.3
SPX2945U-5.0
1%
1%
1%
5.0V
3.3V
5.0V
SPX2945U
33YYWW
SPX2945U
50YYWW
3-Pin TO-220
Corporation
ANALOG EXCELLENCE
Sipex Corporation
Sales Office
22 Linnell Circle
Billerica, MA 01821
Headquarters and
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
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 herein; neither does it convey any license under its patent rights nor the rights of others.
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
11
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