LT1713 LINER [Linear Technology], LT1713 Datasheet - Page 16

• Manufacturer Part Number: LT1713
• Manufacturer: LINER [Linear Technology]

RELATED PARTS
PART NUMBER
LT1016
LT1116
LT1394
LT1671
LT1711/LT1712
LT1719
LT1720/LT1721
LT1713/LT1714
forte of this particular implementation is that it is rail-to-
rail allowing a full-scale analog input. Once the triangle
wave is achieved, the remainder of the pulse width modu-
lator is easy, and is constituted by doing a simple compari-
son using the second half of the LT1714. The triangle wave
and the relatively slow moving analog signal (the one to be
modulated or to do the modulation, depending on how you
look at it) are fed into the inputs of comparator B, whose
output is then the PWM representation of the analog input
voltage. The higher the analog input voltage, the wider the
output pulse. The time averaged output level is thus
proportional to the analog input voltage. This binary
output can then be fed into power transistors with direct
control over motor or speaker winding current, for
16
TYPICAL APPLICATIO
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] FAX: [phone] www.linear-tech.com
V
+
R2
2k
R3
2k
2
1
V
26.1
DESCRIPTION
UltraFast Precision Comparator
12ns Single Supply Ground Sensing Comparator
7ns, UltraFast Single Supply Comparator
60ns, Low Power, Single Supply Comparator
Single/Dual, 4.5ns, 3V/5V/ 5V Rail-to-Rail Comparators
4.5ns, Single Supply 3V/5V Comparator
Dual/Quad, 4.5ns, Single Supply Comparator
+
R1
+
–
1/2 LT1714
= 2.7V TO 7V
3
A
V
15
+
4
16
14
V
+
13
U
R5
1k
499
Figure 9. Rail-to-Rail 1MHz Pulse Width Modulator
R4
C2
0.01 F
500pF
2
3
C1
–
+
LT1809
1
R6
1k
ANALOG
4
INPUT
V
+
7
6
0.001 F
100pF
ANTIALIASING
1k
1MHz
TRIANGLE
WAVE
C4
21
example, with their inherent lowpass characteristic. Care
must be taken to avoid cross conduction in the output
power transistors.
The linearity of the pulse width modulated signal can easily
be ascertained by putting a simple 2-pole RC filter at the
output (as shown in Figure 9). This demodulates the signal
which can then be viewed and compared with the original
input signal on an oscilloscope. Using a spectrum analyzer
and a 1kHz reference signal, this circuit’s distortion prod-
ucts were measured as better than – 50dBc (0.3%) to
about 3.5V
clips at 5V
C3
FILTER
COMMENTS
Industry Standard 10ns Comparator
Single Supply Version of the LT1016
6mA Single Supply Comparator
450 A Single Supply Comparator
Faster Versions of LT1713/LT1714
4mA Comparator with Rail-to-Rail Outputs
Dual/Quad Version of the LT1719
7
8
+
–
1/2 LT1714
6
P-P
P-P
B
V
9
+
5
, degrading to – 30dBc (3%) as the circuit
on a single 5V supply.
10
COMPLEMENTARY
11
1MHz PWM
OUTPUTS
12
FOR LINEARITY MEASUREMENT
0.01 F
16kHz ANALOG FILTER
1k
C5
LINEAR TECHNOLOGY CORPORATION 2000
171314f LT/TP 0501 4K • PRINTED IN USA
0.001 F
10k
C6
171314 F09