NSC LM331N, LM231N, LM231AN, LM231WM, LM131H-883 Datasheet

LM131A/LM131, LM231A/LM231, LM331A/LM331
Precision Voltage-to-Frequency Converters

LM131A/LM131, LM231A/LM231, LM331A/LM331 Precision Voltage-to-Frequency Converters

December 1994

General Description

The LM131/LM231/LM331 family of voltage-to-frequency
converters are ideally suited for use in simple low-cost cir­cuits for analog-to-digital conversion, precision frequency­to-voltage conversion, long-term integration, linear frequen­cy modulation or demodulation, and many other functions.
The output when used as a voltage-to-frequency converter
is a pulse train at a frequency precisely proportional to the
applied input voltage. Thus, it provides all the inherent ad­vantages of the voltage-to-frequency conversion tech­niques, and is easy to apply in all standard voltage-to-fre­quency converter applications. Further, the LM131A/
LM231A/LM331A attains a new high level of accuracy ver­sus temperature which could only be attained with expen­sive voltage-to-frequency modules. Additionally the LM131
is ideally suited for use in digital systems at low power sup­ply voltages and can provide low-cost analog-to-digital con­version in microprocessor-controlled systems. And, the fre­quency from a battery powered voltage-to-frequency con­verter can be easily channeled through a simple photoisola­tor to provide isolation against high common mode levels.

The LM131/LM231/LM331 utilizes a new temperature­compensated band-gap reference circuit, to provide excel­lent accuracy over the full operating temperature range, at
power supplies as low as 4.0V. The precision timer circuit

Typical Applications

has low bias currents without degrading the quick response
necessary for 100 kHz voltage-to-frequency conversion.
And the output is capable of driving 3 TTL loads, or a high
voltage output up to 40V, yet is short-circuit-proof against
V

.

CC

Features

Y

Guaranteed linearity 0.01% max

Y

Improved performance in existing voltage-to-frequency
conversion applications

Y

Split or single supply operation

Y

Operates on single 5V supply

Y

Pulse output compatible with all logic forms

Y

Excellent temperature stability,g50 ppm/§C max

Y

Low power dissipation, 15 mW typical at 5V

Y

Wide dynamic range, 100 dB min at 10 kHz full scale
frequency

Y

Wide range of full scale frequency, 1 Hz to 100 kHz

Y

Low cost

TL/H/5680– 1

1

t

*Use stable components with low temperature coefficients. See Typical Applications section.

**0.1mFor1mF, See ‘‘Principles of Operation.’’

f

OUT

e

V

IN

2.09 V

R

S

#

#

R

RtC

L

FIGURE 1. Simple Stand-Alone Voltage-to-Frequency Converter

g

with

0.03% Typical Linearity (fe10 Hz to 11 kHz)

C

1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.

TL/H/5680

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Supply Voltage 40V 40V 40V
Output Short Circuit to Ground Continuous Continuous Continuous
Output Short Circuit to V
Input Voltage

CC

Operating Ambient Temperature Range

i

i

i

D

D

jA

D

jA

D

JA

at 25§C)

jA

)

Power Dissipation (P
and Thermal Resistance (i

(H Package) P

(N Package) P

(M Package) P

Lead Temperature (Soldering, 10 sec.)

Dual-In-Line Package (Plastic) 260
Metal Can Package (TO-5) 260

ESD Susceptibility (Note 4)

Metal Can Package (TO-5) 2000V
Other Packages 500V 500V

LM131A/LM131 LM231A/LM231 LM331A/LM331

Continuous Continuous Continuous

b

0.2V toaV

T

MINTMAX

b

55§Ctoa125§C

S

b

0.2V toaV

T

MINTMAX

b

25§Ctoa85§C0

S

b

0.2V toaV

T

MINTMAX

Ctoa70§C

§

670 mW
150§C/W

1.25W 1.25W
100§C/W 100§C/W

1.25W
85§C/W

C 260§C 260§C

§

C

§

S

Electrical Characteristics T

e

25§C unless otherwise specified (Note 2)

A

Parameter Conditions Min Typ Max Units

VFC Non-Linearity (Note 3) 4.5VsV

T

MIN

VFC Non-Linearity V

In Circuit of

Figure 1

Conversion Accuracy Scale Factor (Gain) V

LM131, LM131A, LM231, LM231A 0.95 1.00 1.05 kHz/V

S

IN

s

20V

S

s

s

T

T

A

MAX

e

15V, fe10 Hz to 11 kHz

eb

10V, R

e

14 kX

S

g

g

g

0.003

0.006

0.024

g

0.01 % Full-

g

0.02 % Full-

g

0.14 %Full-

LM331, LM331A 0.90 1.00 1.10 kHz/V

s

Temperature Stability of Gain T

LM131/LM231/LM331

MIN

s

T

T

MAX

, 4.5VsV

A

LM131A/LM231A/LM331A

Change of Gain with V

S

4.5VsV
10VsV

Rated Full-Scale Frequency V

Gain Stability vs Time T

(1000 Hrs) Scale

Overrange (Beyond Full-Scale) Frequency V

s

10V 0.01 0.1 %/V

S

s

40V 0.006 0.06 %/V

S

eb

10V 10.0 kHz

IN

s

s

T

MIN

IN

eb

T

A

MAX

11V 10 %

s

20V

S

g

30

g

20

g

0.02 % Full-

g

150 ppm/§C

g

50 ppm/§C

INPUT COMPARATOR

Offset Voltage

LM131/LM231/LM331 T
LM131A/LM231A/LM331A T

Bias Current

Offset Current

Common-Mode Range T

MIN
MIN

MIN

g

s

s

T

T

A

s

s

MAX

s

T

T

A

MAX

s

T

T

A

MAX

b

0.2 V

3

g

4

g

3

b

80

g

8

g

10 mV

g

14 mV

g

10 mV

b

300 nA

g

100 nA

b

2.0 V

CC

Scale

Scale

Scale

2

Electrical Characteristics T

e

25§C unless otherwise specified (Note 2) (Continued)

A

Parameter Conditions Min Typ Max Units

TIMER

Timer Threshold Voltage, Pin 5 0.63 0.667 0.70

Input Bias Current, Pin 5 V

All Devices 0V
LM131/LM231/LM331 V
LM131A/LM231A/LM331A V

V

(Reset) Ie5 mA 0.22 0.5 V

SAT PIN 5

e

15V

S

PIN 5
PIN 5

s

s

V

9.9V

PIN 5

e

10V 200 1000 nA

e

10V 200 500 nA

g

10

g

c

100 nA

CURRENT SOURCE (Pin 1)

Output Current R

LM131, LM131A, LM231, LM231A 126 135 144 mA

e

S

14 kX,V

PIN 1

e

0

LM331, LM331A 116 136 156 mA

Change with Voltage 0VsV

s

10V 0.2 1.0 mA

PIN 1

Current Source OFF Leakage

LM131, LM131A 0.01 1.0 nA
LM231, LM231A, LM331, LM331A 0.02 10.0 nA
All Devices T

e

T

A

MAX

2.0 50.0 nA

Operating Range of Current (Typical) (10 to 500) mA

REFERENCE VOLTAGE (Pin 2)

LM131, LM131A, LM231, LM231A 1.76 1.89 2.02 V
LM331, LM331A 1.70 1.89 2.08 V

Stability vs Temperature

Stability vs Time, 1000 Hours

g

60 ppm/§C

g

0.1 %

LOGIC OUTPUT (Pin 3)

V

SAT

OFF Leakage

Ie5 mA 0.15 0.50 V

e

I

3.2 mA (2 TTL Loads), T

MIN

s

s

T

T

A

MAX

0.10 0.40 V

g

0.05 1.0 mA

SUPPLY CURRENT

LM131, LM131A, LM231, V
LM231A V
LM331, LM331A V

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its specified operating conditions.

Note 2: All specifications apply in the circuit of

Note 3: Nonlinearity is defined as the deviation of f

over the frequency range 1 Hz to 11 kHz. For the timing capacitor, C

Note 4: Human body model, 100 pF discharged through a 1.5 kX resistor.

e

5V 2.0 3.0 4.0 mA

S

e

40V 2.5 4.0 6.0 mA

S

e

5V 1.5 3.0 6.0 mA

S

e

V

40V 2.0 4.0 8.0 mA

S

Figure 3

OUT

, with 4.0VsV

from V

s

40V, unless otherwise noted.

S

c

(10 kHz/b10 VDC) when the circuit has been trimmed for zero error at 10 Hz and at 10 kHz,

IN

, use NPO ceramic, TeflonÉ, or polystyrene.

T

DC
DC

V

S

3

Functional Block Diagram

Pin numbers apply to 8-pin packages only. See connection diagram for LM231WM pin numbers.

TeflonÉregistered trademark of DuPont

FIGURE 1a

TL/H/5680– 2

4

Typical Performance Characteristics

(All electrical characteristics apply for the circuit of

Nonlinearity Error, LM131
Family, as Precision V-to-F
Converter (

Figure 3

)

Figure 3

Nonlinearity Error, LM131
Family

, unless otherwise noted.)

Nonlinearity vs Power Supply
Voltage

Frequency vs Temperature,
LM131A

100 kHz Nonlinearity Error,
LM131 Family (

Power Drain vs V

Figure 4

SUPPLY

)

V

vs Temperature,

REF

LM131A

Nonlinearity Error, LM131
(

Figure 1

)

Output Saturation Voltage vs
I

(Pin 3)

OUT

Output Frequency vs
V

SUPPLY

Input Current (Pins 6, 7) vs
Temperature

Nonlinearity Error, Precision
F-to-V Converter (

Figure 6

)

TL/H/5680– 3

5