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SPX2945
400mA Low Dropout Voltage Regulator with Shutdown
FEATURES
Output 3.3V, 5.0V at 400mA Output Very Low Quiescent Current, 100A Low Dropout Voltage, 420mV at 400mA 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 20V (for SO-8)
VIN IN OUT
ON SHUTDOWN INPUT OFF +VIN 100K 8 +VIN VOUT + 7 R1 0.01F 10F 1 1.2V to 20V
SPX2945
3 SD GND 4
FB
______ ERROR
ERROR 5 R2 VREF OUTPUT
Adjustable Regulator
5V
SPX2945
+ 0.1 F GND + 2.2 F
5V Regulator Circuit
DESCRIPTION
The SPX2945 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 features very low quiescent current (100A 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 lowpower 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 from 1.24V to 20V with an external pair of resistors. Look for SPX2951 for 150mA and SPX2954 for 250mA applications.
TO-220-3 (U) TO-263-3 (T) TO-263-5 (T5) TO-252 (R)
VOU
8-Pin Surface Mount (S)
SOT-223 (M3)
SPX2945 SPX2945
1 1 2 3 2 3
1 2 3 4
8 7 6 5
SPX2945
5 Pin TO-263
SPX2945
1 2 3
SPX2945
SENS SHUTDOWN
V IN FEEDBACK 5V/ 3.3V TAP ERRO
SPX2945
1 2 3
12345
V IN GN V IN GN VOU VOU
GN
VIN GN
V OU
VIN GN
VOU
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
GND VOUT
VIN
SD
Er
(c)Copyright 2004 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
Power Dissipation ........................................................ Internally Limited Lead Temp. (Soldering, 5 Seconds) ............................................. 260C Storage Temperature Range ........................................ -65C to +150C Operating Junction Temperature Range ....................... -40C to +125C 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 = 2.2F, TA = 25C, unless otherwise specified. The denotes the specifications wich apply over full operating tempeture range -40C to +85C, unless noted. PARAMETER 3.3V Version Output Voltage 1mA IL 400mA 5.0V Version Output Voltage 1mA IL 400mA All Voltage Options Output Voltage Temperature Coefficient Line Regulation (Note 3) Load Regulation (Note 3) Dropout Voltage (Note5) 20 (Note1) 6V VIN 20V (Note 4) IL=1 to 400mA IL=1mA IL=400mA Ground Current IL=1mA IL=150mA IL=300mA IL=400mA Current Limit Thermal Regulation Output Noise, 10Hz to 100kHz, IL=100mA PSRR at 100KHz IL=100mA Reference Voltage Reference Voltage Feedback Pin Bias Current Reference Voltage Temp. Coefficient
Rev. B Date:01/20/04
CONDITIONS (Note 2)
MIN
TYP
MAX
UNITS
3.267 3.217 4.950 4.880
3.3 3.3 5.0 5.0
3.333 3.382 5.050 5.120 100
V V mV A mA mA %/W VRMS dB ppm/C mV mV
1.5 6 60 360 100 2 4 8 330 0.05 400 260 31
20 20 30 100 150 450 700 200 300 4 6 8 12 15 25 800 0.2
VOUT=0 CL=2.2F CL=33F CL=10F 1.210 Over Temperature 1.185
Adjustable 8 Pin Version only 1.235 20 20 1.260 1.285 40 60 ppm/C V V nA
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
(c)Copyright 2004 Sipex Corporation
2
ELECTRICAL CHARACTERISTICS: Continued
Electrical characteristics at VIN = VO+1V, IO = 1mA, COUT = 2.2F, TA = 25C, unless otherwise specified. applies over the full operating temperature range. PARAMETER Feedback Pin Bieas Current Temperature Coefficient Output Leakage Current Output Low Voltage Upper Threshold Voltage Lower Threshold Voltage Hysteresis Input Logic Voltage Shutdown Pin Input Current V0H=20V VIN=4.5V I0L=400A (Note 6) (Note 6) (Note 6) Low (Regulator ON) High (Regulator OFF) VS=2.4V VS=26V Regulator Output Current in Shutdown (Note 7) 10 20 40 25 CONDITIONS (Note 2) MIN TYP 0.1 0.01 150 60 75 15 1.3 30 450 3 0.7 2.0 50 100 600 750 A 95 140 1 2 250 400 MAX UNITS nA/C A mV mV mV mV V A
Note 1: Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range. Note 2: Unless otherwise specified all limits are guaranteed for Tj = 25C, VIN = 6V, IL = 1mA and CL = 2.2F. Additional conditions for the 8-pin versions are feedback tied to 5V/3.3V tap and output tied to output sense (VOUT = 5V) and VSHUTDOWN 0.8V. Note 3: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. 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 150C for IL = 1 mA. For TJ = 125C, 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 constant as a percent of VOUT as VOUT is varied, with the dropout warning occurring at typically 5% below nominal, 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
(c)Copyright 2004 Sipex Corporation
3
SPX2945 - 5.0V BLOCK DIAGRAM
UNREGULATED DC 7
FEEDBACK
+
8
INPUT
1
OUTPUT
5V at 400mA MAX
2 SENSE + _ FROM CMOS OR TTL 3
SHUTDOWN
180k ERROR AMPLIFIER
. 6 5V TAP 330k . + 5 ______ ERROR 1F TO CMOS OR TTL 4
60k .
+
60 mV + 1.23V
+ _ ERROR DETECTION COMPARATOR
REFERENCE GROUND
APPLICATION INFORMATION External Capacitors The stability of the SPX2945 requires a 2.2F 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 -25C solid tantalum is recommended since the many aluminum types have electrolytes that freeze at about -30C. The ESR of about 5 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 0.5F and 0.15F 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 4.7F or greater must be used for the condition of 250mA load at 1.23V output.
The SPX2945, 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 applications like CMOS RAM keep-alive. 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 0.1F 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 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 3.3F.
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
(c)Copyright 2004 Sipex Corporation
4
Error Detection Comparator Output The Comparator produces a logic low output whenever the SPX2945 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 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. 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 400A; this value adds to battery drain in a low battery condition. Suggested values range from 100K to 1M. If the output is unused this resistor is not required. 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 (feedback) 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. Refer to the below equation for the programming 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 recommended load current of 1 A forces an upper limit of 1.2 M 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 12A. Since the SPX2945 typically draws 60 A 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 SPX2945 but is relatively inefficient, as increasing the capacitor from 1F to 220F only decreases the noise from 430V to 160V 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 CBYPASS 1 / 2R1 x 200 Hz or choose 0.01F. When doing this, the output capacitor must be increased to 3.3F to maintain stability. These changes reduce the output noise from 430V to 100V 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.
4.75V OUTPUT VOLTAGE _______ ERROR*
+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
(c)Copyright 2004 Sipex Corporation
5
PACKAGE: 3 PIN TO-252
E b2
-AL2 A A1 C1
-BA
4 SEATING PLANE L3 L1 L H
D 1 -C2 3
b1 3 PLCS
.010
M AM
c
8
e e1 D1
A
C
TERM 4
E1
NOTES 1. Refer To Applicable Symbol List. 2. Dimensions And Tolerancing Per Ansi Y14.5m - 1982. 3. Lead Dimension Uncontrolled in L3 4. Tab Contour Optional Within Dim. b2 & L2 And E1 & D1 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.
S Y M B O L
BACK VIEW A-A
INCHES MIN. 0.086 0.035 0.025 0.300 0.205 0.018 0.018 0.235 0.170 0.250 0.170 0.098 0.180 0.370 0.020 0.025 0.035 0.045 0.410 0.040 0.050 0.060 9.398 0.508 0.635 0.889 1.143 MAX 0.094 0.045 0.035 0.045 0.215 0.023 0.023 0.245 0.265 MIN. 2.184 0.889 0.635 7.620 5.207 0.457 0.457 5.969 4.318 6.350 4.318
MM MAX 2.3876 1.143 0.889 1.143 5.461 0.5842 0.5842 6.223 6.731 2.489 4.572 10.414 1.016 1.270 1.524
N O T E
A A1 b b1 b2 c c1 D D1 E E1 e e1 H L L1 L2 L3
4
4,5 4,5
6 4 3
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
(c)Copyright 2004 Sipex Corporation
6
PACKAGE: 3 PIN TO-220
0.151D 0.002 (3.835 D 0.051) 0.408 0.013 (10.36 0.33) 0.110 0.010 (2.794 0.254)
0.180 0.005 (4.572 0.127) 0.050 0.002 (1.270 0.051)
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) 7Typ.
0.150 MIN (3.81 MIN) 0.540 0.015 (13.720 0.381)
0.410 (10.41)
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. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
(c)Copyright 2004 Sipex Corporation
7
PACKAGE: 5 PIN TO-263
0.055 (1.397) 0.405 0.005 (10.287 0.127)
0.176 0.005 (4.470 0.127) 0.050 0.002 (1.270 0.051)
0.356 0.005 (9.042 0.127)
0.600 0.025 (15.24 0.635)
0.100 0.010 (2.540 0.254)
0.067 0.005 (1.702 0.127)
0.032 0.003 (0.813 0.076)
0.015 (0.381
+ 0.003 + 0.074) 0 8
PACKAGE: 3 PIN TO-263
0.405 0.005 (10.287 0.127)
0.055 (1.397)
0.176 0.005 (4.470 0.050 0.002 (1.270

0.127) 0.051)
0.356 (9.042

0.005 0.127) 0.600 0.025 (15.24 0.635) 0.100 0.010 (2.540 0.254)
0.103 BSC (2.616)
0.050 (1.270) 0.032 + 0.001 (0.813 + 0.025) -
0.015 (0.381
+ + -
0.003 0.074) 0 8
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
(c)Copyright 2004 Sipex Corporation
8
PACKAGE: 3 PIN SOT-223
0.124 0.116
0.146 0.295 0.130 0.264
0.0905 NOM 0.181 NOM
0.041 0.033
0.067 0.028 0.264 0.248
16C 10C 0.014 0.010
0.0040 0.0008
10C Max
0.033 0.025
16C 10C
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
(c)Copyright 2004 Sipex Corporation
9
PACKAGE: 8 PIN NSOIC
D e
E/2 E1 E E1/2
SEE VIEW C
1 INDEX AREA (D/2 X E1/2) A b
O1
TOP VIEW
WITH PLATING
b
Gauge Plane L2 Seating Plane
O1
L L1
O
c
VIEW C
BASE METAL
CONTACT AREA
DIMENSIONS Minimum/Maximum (mm)
8 Pin NSOIC
(JEDEC MS-012, AA - VARIATION)
COMMON HEIGHT DIMENSION
A
A2 SEATING PLANE A1
SIDE VIEW
SYMBOL A A1 A2 b c D E E1 e L L1 L2 O O1
MIN NOM MAX 1.75 1.35 0.25 0.10 1.25 1.65 0.31 0.51 0.17 0.25 4.90 BSC 6.00 BSC 3.90 BSC 1.27 BSC 0.40 1.27 1.04 REF 0.25 BSC 0 8 5 15
8 PIN NSOIC
Rev. B Date:01/20/04 SPX2945 400mA Low Dropout Voltage Regulator with Shutdown (c)Copyright 2004 Sipex Corporation
10
ORDERING INFORMATION
Ordering No.
Top Mark 2945M3 33YYWW 2945M3 50YYWW 2945S33 33YYWW SPX2945R 50YYWW SPX2945R 504YYWW SPX2945R YYWW SPX2945T 33YYWW SPX2945T5 50YYWW SPX2945T5 33YYWW SPX2945T 50YYWW SPX2945U 33YYWW SPX2945U 50YYWW
Accuracy
Output Voltage
Packages 3-Pin SOT-223 3-Pin SOT-223 8-Pin SOIC 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
SPX2945R-3.3
1%
3.3V
3-Pin TO-252
SPX2945R-5.0
1%
5.0V
3-Pin TO-252
SPX2945T-3.3
1%
3.3V
3-Pin TO-263
SPX2945T-5.0
1%
5.0V
3-Pin TO-263
SPX2945T5-3.3
1%
3.3V
5-Pin TO-263
SPX2945T5-5.0 SPX2945U-3.3 SPX2945U-5.0
1% 1% 1%
5.0V 3.3V 5.0V
5-Pin TO-263 3-Pin TO-220
3-Pin TO-220
Corporation
ANALOG EXCELLENCE Sipex Corporation Headquarters and Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600 Sales Office 22 Linnell Circle Billerica, MA 01821 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
(c)Copyright 2004 Sipex Corporation
11

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