Rev. 08/13/02 SPX1431 Precision Adjustable Shunt Regulator

Precision Adjustable Shunt Regulator

SPX1431

DESCRIPTION

FEATURES

Trimmed Bandgap Reference to 0.4%

Wide Operating Current 1mA to 150mA

Extended Temperature Range:
-55

C to 125

Low Temperature Coefficient 30 ppm/

Offered in TO-92, SOIC, SOT-89,
SOT-23-5

Improved Replacement in Performance for
LT1431

Low Cost Solution

The SPX1431 is a 3-terminal adjustable shunt voltage regulator providing a highly accurate
bandgap reference. The SPX1431 acts as an open-loop error amplifier with a 2.5V temperature
compensation reference. The SPX1431's thermal stability, wide operating current (150mA)
and temperature range (-55

C to 125

C) makes it suitable for a variety of applications that

require a low cost, high performance solution. SPX1431 tolerance of 0.4% is proven to be
sufficient to overcome all of the other errors in the system to virtually eliminate the need for
trimming in the power supply manufacturer's assembly lines and contributes a significant cost
savings.

The output voltage may be adjusted to any value between V

REF

and 36 volts with two external

resistors. The SPX1431 is available in TO-92, SOIC-8, SOT-89, and SOT-23-5 packages.

APPLICATIONS

Battery Operating Equipment

Adjustable Supplies

Switching Power Supplies

Error Amplifiers

Single Supply Amplifier

Monitors / VCRs / TVs

Personal Computers

BLOCK DIAGRAM

2.5V

Reference
(R)

Anode (A)

Cathode (K)

Rev. 08/13/02 SPX1431 Precision Adjustable Shunt Regulator

ABSOLUTE MAXIMUM RATINGS

Cathode-Anode Reverse Breakdown V

....................................... 37V

Anode-Cathode Forward Current, (<10ms) I

................................. 1A

Operating Cathode Current I

.................................................. 150mA

Reference Input Current I

REF

........................................................ 10mA

Continuous Power Dissipation at 25

C P

TO-92 ..................................................................... 775mW
SOT-23 .................................................................. 200 mW
SOIC-8 .................................................................... 750mW
SOT-89 ................................................................. 1000mW

Junction Temperature T

........................................................... 150

Storage Temperature T

STG

.............................................. -65 to 150

Lead Temperature (Soldering 10 sec.) T

.................................. 300

NOTE: Stresses greater than those listed under ABSOLUTE MAXIMUM
RATINGS may cause permanent damage to the device. This is a stress
rating only and functional operation of the device at these or any other
conditions above those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating condi-
tions for extended periods may affect reliability.

TYPICAL THERMAL RESISTANCES

PACKAGE

TYPICAL DERATING

TO-92

160

C/W 80

C/W

6.3 mW/

SOT-23

575

C/W 150

C/W

1.7 mW/

SOIC-8

175

C/W 45

C/W

5.7 mW/

SOT-89

110

C/W

9.1mW/C

Typical deratings of the thermal resistances are given for ambient
temperature >25

ELECTRICAL CHARACTERISTICS

Electrical characteristics at 25

°C I

= 10mA V

= V

REF

, unless otherwise specified.

PARAMETER

SYMBOL

FIGURE

CONDITIONS

MIN

TYP

MAX

UNITS

SPX1431

Reference Voltage

REF

2.490

2.500

2.510

= 0

C to 105

2.465

2.535

REF

withTemp.*

0.07

0.20

mV/

Ratio of Change in V

REF

= 3V to 36V

-2.0

-1.1

mV/V

to Cathode Voltage

Reference Input Current

REF

0.7

1.9

REF

Temp Deviation

REF

= 0

C to 105

0.4

1.2

Min I

for Regulation

K(MIN)

0.4

Off State Leakage

K(OFF)

REF

= 0V,

0.04

250

= 36V

Dynamic Output

1kHz

0.15

0.5

Impedance

= 1 to 150mA

Operating Range (T

) = - 55

C to 125

* See appropiate test circuit (Figure 2)

RECOMMENDED CONDITIONS

PARAMETER

SYMBOL

RATING

UNIT

Cathode Voltage

REF

to 36

Cathode Current

Rev. 08/13/02 SPX1431 Precision Adjustable Shunt Regulator

REF

105

-10

0.5

5000

0.07 mV/

0.003 %/

27 ppm/

ppm

Junction Temperature (

TC in ppm/

C =

TC in %/

C =

TC in mV/

C =

REF

(mV)

(

REF

at 25

)

REF

x 100

(

REF

at 25

)

REF

x 10

CALCULATING AVERAGE TEMPERATURE COEFFICIENT (TC)

Figure 1. V

REF

VS Temperature.

TEST CIRCUITS

REF

KA =

REF

)

K (OFF)

Figure 2. Test Circuit for V

= V

REF

Figure 3. Test Circuit for V

> V

REF

Figure 4. Test Circuit for I

KOFF

Rev. 08/13/02 SPX1431 Precision Adjustable Shunt Regulator

-2

-1

150

125

100

-25

-50

-75

-100

Cathode Voltage (V)

Cathode Current (mA)

= V

REF

C to 105

-60

-30

120

2.53

2.52

2.51

2.50

2.49

2.48

2.47

2.46

2.45

Ambient Temperature (

REF

Reference V

ltage (V)

= V

REF

= 10mA

TYPICAL PERFORMANCE CHARACTERISTICS

Figure 5. High Current Operating Characteristics

Figure 6. Reference Voltage VS Ambient Tempetature

-1.0

1.0

2.0

3.0

900

800

700

600

500

400

300

200

100

-100

-200

Cathode Voltage (V)

Cathode Current (

= V

REF

to 105

105

-0

-60

-30

120

3.0

2.5

2.0

1.5

1.0

0.5

Ambient Temperature (

REF

Reference Input Current (

R1 = 10k

R2 =

= 10mA

Figure 7. Low Current Operating Characteristics

Figure 8. Reference Input Current VS Ambient
Temperature

12 15

27 30

-10

-20

-30

-40

-50

Cathode Voltage (V)

REF

(mV)

125

= 10mA

Figure 9. Reference Voltage Line Regulation VS
Cathode Voltage and T

AMBIENT

100

10K

100K

f Frequency (Hz)

Noise V

ltage nV

= V

REF

= 10mA

= 25

Figure 10. Noise Voltage VS Frequency

Rev. 08/13/02 SPX1431 Precision Adjustable Shunt Regulator

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

-60

-30

120

0.150

0.125

0.100

0.075

0.050

0.025

0.0

Free Air Temperature

Dynamic Impedance (

)

= V

REF

= 1 to 100mA

1kHz

Figure 11. Low Frequency Dynamic Output Impedance
VS T

AMBIENT

100

10K

100K

10M

START 10.000Hz

STOP 50 000 000.000Hz

REF LEVEL
60.000dB
0.0deg

/DIV
10.000dB
45.000deg

MARKER 19 422
MAG (A/R)
MARKER 19 422
PHASE (A/R)

611.000Hz
-0.125dB
611.000Hz
46.717deg

PHASE

GAIN

Figure 12. Small Signal Gain and Phase VS Frequency;
I

= 10mA, T

= 25

°C

15k

8.25k

OUT

GND

230

Figure 13. Test Circuit for Gain and Phase Frequency
Response

Figure 14. Frequency = 100kHz, I

= 10mA, T

= 25

°C

Figure 15. Test Circuit for Pulse Response

Figure 16. Stability Boundary Conditions

OUT

GND

250

p = 100kHz

100

Load Capacitance (pF)

Cathode Current (mA)

A: V

= V

REF

B: V

= 5V at I

=10mA

C: V

=10V at I

=10mA

D: V

=15V at I

=10mA

STABLE

A = 25

OUT

Part Number SPX1431