TSM921 TOUCHSTONE [Touchstone Semiconductor Inc], TSM921 Datasheet - Page 16

• Manufacturer Part Number: TSM921
• Description: Ultra-Low-Power, Single/Dual-Supply Comparators
• Manufacturer: TOUCHSTONE [Touchstone Semiconductor Inc]

TSM921-TSM924
Page 16
Figure 6. Bar-Graph Level Gauge
6. Using the equations below, verify all resistor
In this example, a 1MΩ, 1% standard value
resistor is selected for R3.
values selected:
V
= 5.474V
V
Where the hysteresis voltage is given by:
V
OTH
OTH
HYS
4.484V
(V
(V
V
REF
REF
REF
x
+ V
R5
R4
V
HYS
HYS
) x
) x
R1 + R2 + R3
R1 + R2 + R3
(R1+R2)
R1
Bar-Graph Level Gauge
A simple four-stage level detector is shown in
Figure 6 using the TSM924. Due to its high output
source capability, the TSM921 is perfect for driving
LEDs. When all of the LEDs are on, the threshold
voltage is set by resistors R1 and R2 where V
+ R2)/R1 volts. All other threshold voltages are
scaled down accordingly by ¾, ½, and ¼ the
threshold voltage. The current through the LEDs is
limited by the output resistors.
Level Shifter
Figure 7 provides a simple way to shift from bipolar
±5V inputs to TTL signals by using the TSM924. To
protect the comparator inputs, 10kΩ resistors are
placed in series and do not have an effect on the
performance of the circuit.
Figure 7. Level Shifter: ±5V Input into CMOS output
TSM921_24DS r1p0
IN
RTFDS
=(R1