©2001 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.0
Features
• Guaranteed linearity: 0.01% max.
• Low power dissipation: 15mW at 5V
• Wide range of full scale fre qu ency: 1Hz to 100KHz
• Pulse output compatible with all logic forms
• Wide dynamic range: 100dB min at 10KHz full scale
frequency
Description
This voltage to frequency converter provides the output
pulse train at a frequency precisely proportional to the
applied input voltage. The LM331 can operate at power
supplies as low as 4.0V and be changed output frequency
from 1Hz to 100KHz. It is ideally suited for use in simple
low co st cir cui t f or a na log-to di g i tal c o nve r si o n, l on g t er m
integration, linear frequency modulation or demodulation,
frequency to voltage conversion, and many other functions.
Internal Block Diagram
LM331
V-F Converter
8-DIP
1
LM331
2
Absolute Maximum Ratings (TA = 25°
°°
°C)
Electrical Characteristics
Parameter Symbol Value Unit
Supply Voltage VCC 40 V
Input Voltage VI-0.2 ~ + VCC V
Operating Temperature Range TOPR 0 ~ +70 °C
Power Dissipation PD500 mW
Parameter Symbol Conditions Min. Typ. Max. Unit
VFC Non-Linearity VFCNL 4.5 ≤ VCC ≤ 20V - ±0.003 ±0.01 % Full-Scale
Conversion Accuracy Scale Factor ACCUR VI = -10V, RS = 14KΩ0.90 1.00 1.10 KHz/V
Chang Of Gain With VCC VCC∆G/VCC 4.5V ≤ VCC ≤ 10V - 0.01 0.1 %/V
10V ≤ VCC ≤ 40V - 0.006 0.06
Rated Full - Scale Frequency f VI = -10V 10.0 - - KHz
INPUT COMPARATOR
Offset Voltage VIO 0°C ≤ TA ≤ +70°C-±3±10 mV
Bias Current IBIAS - - -80 -300 nA
Offset Current IIO --±8±100 nA
Common-Mode Range VCM 0°C ≤ TA ≤ +70°C-0.2-VCC-
2.0 V
TIMER (PIN 5)
Timer Threshold Voltage VTH - 0.63 0.667 0.701 ×VCC
Input Bias Current IBIAS VCC = 15V,
0V ≤ V5 ≤ 9.9V -±10 ±100 nA
V5 = 10V - 200 1000 nA
Saturation Voltage VSAT I = 5mA - 0.22 0.5 V
CURRENT SOURCE (PIN 1)
Output Current IO RS = 14KΩ, V1= 0V 116 136 156 µA
Change with Voltage ∆IO/∆V1 0V ≤ V1 ≤ 10V - 0.2 1.0 µA
Current Source Off Leakage ILKG - - 0.02 10.0 nA
REFERENCE VOLTAGE (PIN 2)
Reference Voltage VREF - 1.70 1.89 2.08 VDC
Stability vs Temperature STT--±60 - ppm/°C
Stability vs Time, 1000Hours STT--±0.1 - %
LOGIC OUTPUT (Pin 3)
Saturation Voltage VSAT I = 5mA - 0.15 0.50 V
I = 3.2mA - 0.10 0.40
Off Leakage ILKG --±0.05 1.0 µA
SUPPLY CURRENT
Supply Current ICC VCC = 5V 1.5 3.0 6.0 mA
VCC = 40V 2.0 4.0 8.0
LM331
3
Typical Applications
Figure 1. Precision Voltage-to-Frequency Converter, 100KHz Full-Scale
Figure 2. Simple Frequency-to-Voltage Converter, 10KHz Full-Scale
Figu re 3. Light Int ensity to Frequency Conv erter
LM331
LM331
LM331
LM331
4
Mechanical Dimensions
Package Dimensions in millimeters
6.40
±0.20
3.30
±0.30
0.130
±0.012
3.40
±0.20
0.134
±0.008
#1
#4 #5
#8
0.252
±0.008
9.20
±0.20
0.79
2.54
0.100
0.031
()
0.46
±0.10
0.018
±0.004
0.060
±0.004
1.524
±0.10
0.362
±0.008
9.60
0.378 MAX
5.08
0.200
0.33
0.013
7.62
0~15°
0.300
MAX
MIN
0.25
+0.10
–0.05
0.010
+0.004
–0.002
8-DIP
LM331
5
Ordering Information
Product Number Package Operating Temperature
LM331N 8-DIP 0 ~ + 70°C
LM331
5/22/01 0.0m 001
Stock#DSxxxxxxxx
2001 Fairchild Semicond uctor Corporation
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reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or syst em who se failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effec tiv ene ss.
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