LTC1842CS8 Linear Technology, LTC1842CS8 Datasheet - Page 9

• Manufacturer Part Number: LTC1842CS8
• Description: IC COMP ULTLOPWR W/REF DUAL8SOIC
• Manufacturer: Linear Technology
• Type: with Voltage Referencer

Specifications of LTC1842CS8

• Number Of Elements: 2
• Output Type: Open Drain
• Voltage - Supply: 2.5 V ~ 11 V, ±1.25 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIONS
1. Choose the required hysteresis voltage band and
2. Select R1. The leakage current into IN B
3. Calculate R2 + R3. The overvoltage threshold should be
4. Calculate R2. The undervoltage threshold should be set
calculate values for R4 and R5 according to the formu-
las in the hysteresis section. In this example, 5mV of
hysteresis has been added at the comparator input
(V
will be larger because of the input resistor divider.
so the current through R1 should exceed 100nA, to
ensure threshold accuracy. R1 values up to about 10M
can be used, but values in the 100k to 1M range are
usually easier to deal with. In this example choose
R1 = 294k.
set at 5.5V. The design equation is as follows:
at 4.5V. The design equation is as follows:
R
R
2
2
H
= V
R
62 2
R
294
3
HB
1
.
/2). Note that the hysteresis apparent at V
k
k
R
1 068
294
R
.
1
2
1 068
k
V
.
REF
R
U
M
1 182 0 005
V
3
.
UTH
M
V
REF
INFORMATION
V
5 5
U
V
1 182 0 005
H
.
LTH
.
–
–
1
.
V
4 5
H
– .
.
–
W
–
R
1
1
–
–
294
is under 1nA
U
k
IN
5. Calculate R3:
6. Verify the resistor values. The equations are as
Choose R2 = 61.9k (1% standard value)
R3 = (R2 + R3) – R2
Choose R3 = 1M (1% standard value)
follows, evaluated for the above example:
Overvoltage threshold:
Undervoltage threshold:
where the hysteresis voltage V
V
V
UTH
OTH
LTC1841/LTC1842/LTC1843
= 1.068M – 61.9k
= 1.006M
5 474
4 484
V
V
.
.
REF
REF
V
V
–
V
V
H
H
R
R
1
1
R
1
R
R
R
2
2
1
R
2
R
R
H
3
3
V
REF
R
R
5
4
9