LTC1445 Linear Technology, LTC1445 Datasheet - Page 8

• Manufacturer Part Number: LTC1445
• Description: Ultralow Power Quad Comparators with Reference
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
LTC1443/LTC1444/LTC1445
Bypassing the reference can help prevent false tripping of
the comparators by preventing glitches on the V
reference output voltage. Figure 3 shows the bypassed
reference output with a square wave applied to the V
Resistors R1 and R2 set 10mV of hysteresis, while R3
damps the reference response. Note that the comparator
output doesn’t trip.
Hysteresis
Hysteresis can be added to the LTC1444/LTC1445 by
connecting a resistor (R1) between the REF and HYST
pins, and a second resistor (R2) from HYST to V
8
5V
TO 8V
Figure 3a. V
R2
2.4M
10k
R1
U
R3
430
C1
1.0 F
14
+
4
8
5
Glitching Test Circuit
U
IN A
IN A
HYST
REF
+
–
+
–
V
+
W
3
9
LTC1445
LTC1443/44/45 • F03
V
–
I
REF
2
Figure 4. Programmable Hysteresis
OUT
R1
R2
–
U
(Figure 4).
+
14
8
or the
+
HYST
REF
pin.
LTC1445
LTC1443/44/45 • F04
9
The difference between the upper and lower threshold volt-
ages or hysteresis voltage band (V
voltage difference between the REF and HYST pins. When
more hysteresis is added, the upper threshold increases the
same amount as the lower threshold decreases. The maxi-
mum voltage allowed between REF and HYST is 50mV,
producing a maximum hysteresis voltage band of 100mV. If
hysteresis is not wanted, the HYST pin should be shorted to
REF. Acceptable values for I
2.4M is chosen for R2, then R1(k ) = V
R1 =
R2 =
V
+
V
OUT
REF
8V
5V
(2)(I
1.221V –
V
HB
I
REF
REF
Figure 3b. V
)
V
HB
2
+
2ms/DIV
Glitching Response
REF
range from 0.1 A to 5 A. If
HB
LTC1443/1444/1445 • TA02
) is equal to twice the
HB
(mV).