LTC1421-2.5CSW#PBF Linear Technology, LTC1421-2.5CSW#PBF Datasheet - Page 10

• Manufacturer Part Number: LTC1421-2.5CSW#PBF
• Manufacturer: Linear Technology

Specifications of LTC1421-2.5CSW#PBF

• Linear Misc Type: Positive Low Voltage
• Family Name: LTC1421
• Package Type: SOIC W
• Operating Supply Voltage (min): 3V
• Operating Supply Voltage (max): 12V
• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 24
• Lead Free Status / Rohs Status: Compliant

APPLICATIONS
LTC1421/LTC1421-2.5
Figure 8c shows how the comparator can be used to
generate a reset when the 12V supply (V
below 10.8V. The 5V supply (V
reset when it dips below 4.65V. When the 12V supply
drops below 10.8V, COMPOUT will pull the FB pin low
setting the internal threshold voltage for comparator 1 to
5.88V. Since V
ately goes low and a reset is generated 32 s later.
Figure 8d shows how the comparator can be used to
override the internal reset voltage for a 5V supply on
V
10
OUTLO
6
7
6
7
V
V
CCLO
CCLO
Figure 8c. Reset 12V at 10.8V, Reset 5V at 4.65V
.
V
V
20 A
20 A
CCLO
CCLO
Figure 8b. Monitor 5V, Reset 3.3V at 2.9V
20 A
20 A
TIMING
TIMING
RESET
1.232V
1.232V
RESET
OUTLO
COMP1
COMP1
U
is less than 5.88V, PWRGD immedi-
–
+
–
+
INFORMATION
U
3.3V
COMP2
COMP2
5V
20
20
OUTLO
73.5k
26.7k
73.5k
26.7k
W
71.5k
71.5k
LTC1421
LTC1421
) also generates a
+
–
+
–
1421 F08b
16
11
15
13
14
8
1421 F08c
16
11
15
13
14
8
OUTHI
U
10k
5%
) drops
12V
5V
107k
1%
38.3k
1%
107k
1%
13.7k
1%
A 5.1k resistor is tied from the FB pin to V
internal threshold to about 2.9V. The new reset threshold
voltage is set by the external resistive divider connected to
COMP2. When V
COMPOUT pulls FB to ground, changing the internal
threshold at COMP1 to 5.88V and generating a reset.
Finally, the comparator may be used to monitor a negative
supply as shown in Figure 8e. The external resistor divider
6
7
6
7
V
V
CCLO
Figure 8e. Monitor – 12V at – 10.8V, Reset 5V at 4.65V
CCLO
V
20 A
V
20 A
CCLO
CCLO
20 A
20 A
TIMING
RESET
1.232V
TIMING
1.232V
RESET
Figure 8d. Reset 5V at 4.5V
OUTLO
COMP1
COMP1
drops below the new threshold,
–
+
–
+
COMP2
COMP2
5V
5V
20
20
73.5k
26.7k
73.5k
26.7k
71.5k
71.5k
LTC1421
LTC1421
+
–
+
–
1421 F08e
OUTLO
1421 F08d
16
11
15
13
14
8
16
11
15
13
14
8
– 12V
, setting the
5.1k
5%
12V
12V
13.7k
1%
107k
1%
10k
5%
102k
1%
38.3k
1%