SG2731 Microsemi Corporation, SG2731 Datasheet - Page 4

• Manufacturer Part Number: SG2731
• Description: Dc Motor Pulse Width Modulator
• Manufacturer: Microsemi Corporation

4/90 Rev 1.3 9/99
Copyright
APPLICATION INFORMATION
the lower threshold causes Output B to switch to the HIGH state.
If V
Threshold crossings are generated by shifting the triangle
waveform up and down with the error voltage (Pin 5). A positive
error voltage will result in a pulse width modulated output at
Driver A (Pin 13). Similarly, a negative error voltage produces a
pulse train at Driver B (Pin 12). Figure 2 illustrates this process
for the case where V
It is important to note that the triangle shifting circuit also
attenuates the waveform seen at C
in a waveform at the PWM comparators with a positive peak of
V + and a negative peak of V
when selecting the values for +V
APPLICATION CIRCUITS
In this simple battery-powered position servo, the control supply
and driver supply are both single-ended positive with respect to
ground.
V
S
. If V
S
is less than 8V then V
1999
S
is greater than 8V use zeners.
+
is greater than V
T
FIGURE 3
can be obtained with resistors from
-
, and must be taken into account
T
and -V
T
by a factor of 2. This results
(continued)
T
T
.
.
4
A high torque position servo is obtained by buffering the output
drivers to obtain higher output current.
FIGURE 2 - PULSE WIDTH MODULATION WITH NO DEADBAND
SG1731/SG2731/SG3731
FIGURE 4
11861
Western
L
[phone]
INFINITY
Avenue
Garden
Microelectronics
FAX: [phone]
Grove,
CA
92841
Inc.