ltc1727es8-5-trpbf Linear Technology Corporation, ltc1727es8-5-trpbf Datasheet - Page 12

• Manufacturer Part Number: ltc1727es8-5-trpbf
• Description: Micropower Precision Triple Supply Monitors In 8-lead Msop And 5-lead Sot-23 Packages
• Manufacturer: Linear Technology Corporation

APPLICATIO S I FOR ATIO
LTC1727/LTC1728
Figure 4 contains a simple circuit for 5V systems that can’t
risk the RST output going high in the 3.1V to 4.15V range
(possibly due to very slow rise time on the 5V supply).
Diode D1 powers the LTC1728-5 while dropping ≈ 0.6V
from the V
internal override circuit from being activated. Without the
override circuit active, the RST pin stays low until V
reaches V
TYPICAL APPLICATIO S
12
5V
0.1µF
Figure 4. LTC1728-5 Monitoring a Single 5V
Supply. D1 Used to Avoid RST High Near 3.1V
to 4V (See Figure 3).
RT5
CC5
≅ 4.675V. (See Figure 5.)
pin to the V
D1
5
4
3
2
U
D1: MMBD914 OR EQUIVALENT
V
V
V
GND
CC3
CC5
CCA
LTC1728-5
CC3
U
ADJUSTABLE SUPPLY
OR DC/DC FEEDBACK
RST
pin. This prevents the part’s
1
U
W
DIVIDER
Triple Supply Monitor (3.3V, 5V and Adjustable)
R1
10k
TO SYSTEM
RESET
R1*
*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL
COMBINATION OF R1 AND R2 ≤ 66.5k
1727/28 F04
U
3.3V
5V
R2*
CC5
5
4
3
2
V
V
V
GND
CC3
CC5
CCA
LTC1728-5
LTC1727-2.5/LTC1728-2.5/LTC1728-1.8/LTC1728-3.3
Override Functions
The V
V
V
point for V
be tied to V
V
result in the continuous assertion of RST.
CC18
CC3
CC25
RST
and V
CCA
. This is an obvious solution since the trip points for
/V
1
1727/28 TA03
CC18
pin, if unused, can be tied to either V
SYSTEM RESET
CCA
CC25
CC3
Figure 5. RST Output Voltage
Characteristics of the Circuit in Figure 4
5
4
3
2
1
0
and operating off of a 2.5V/1.8V supply will
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
. Likewise, the V
V
10k PULL-UP FROM RST TO V
T
. V
A
/V
CC5
= 25°C
CC3
CC18
= V
CCA
must always be used. Tying V
will always be greater than the trip
= 0V TO 5V
V
CC5
(V)
CC25
CC5
/V
CC18
1727/28 F05
, if unused, can
CC3
or V
CC3
CC25
17278fb
to
/