NTE864 NTE ELECTRONICS, NTE864 Datasheet - Page 3

• Manufacturer Part Number: NTE864
• Description: Replacement Semiconductors DIP-14 PREC WVFM GEN
• Manufacturer: NTE ELECTRONICS

Specifications of NTE864

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

An external capacitor C is charged and discharged by two current sources. Current source #2 is
switched on and off by a flip-flop, while current source #1 is on continuously. Assuming that the flip-
flop is in a state such that current source #2 is off, and the capacitor is charged with a curent I, the
voltage across the capacitor rises linearly with time. When this voltage reaches the level of comparat‐
or #1 (set at 2/3 of the supply voltage), the flip-flop is triggered, changes states, and releases current
source #2. This current source normally carries a current 2I, thus the capacitor is discharged with a
net-current I and the voltage across it drops linearly with time. When it has reached the level of com‐
parator #2 (set at 1/3 of the supply voltage), the flip-flop is triggered into its original state and the cycle
starts again.
Four waveforms are readily obtainable from this basic generator circuit. With the current source set
at I and 2I respectively, the charge and discharge times are equal. Thus a triangle waveform is created
across the capacitor and the flip-flop produces a square wave. Both waveforms are fed to buffer
stages and are available at Pin3 and Pin9.
The levels of the current sources can, however, be selected over a wide range with two external resist‐
ors. Therefore, with the two currents set at values different from I and 2I, an asymmetrical sawtooth
appears at Pin3 and pulses with a duty cycle from less than 1% to greater than 99% are available at
Pin9.
The sine wave is created by feeding the triangle wave into a nonlinear network (sine converter). This
network provides a decreasing shunt impedance as the potential of the triangle moves toward the two
extremes.
Duty Cycle Adjust
Duty Cycle Adjust
Sawtooth Wave
Sine Adjust
Sine Wave
FM Bias
(+) V
CC
Pin Connection Diagram
1
2
3
4
5
6
7
14
13
12
11
10
9
8
N.C.
N.C.
Sine Adjust
GND
Timing Capacitor
Square Wave
FM Sweep Input