LTC1727 Linear Technology, LTC1727 Datasheet - Page 11

• Manufacturer Part Number: LTC1727
• Description: Micropower Precision Triple Supply Monitors in 8-Lead MSOP and 5-Lead SOT-23 Packages
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
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
RT5
CC5
pin to the V
4.675V. (See Figure 5.)
U
CC3
U
pin. This prevents the part’s
W
5V
0.1 F
Figure 4. LTC1728-5 Monitoring a Single 5V
Supply. D1 Used to Avoid RST High Near 3.1V
to 4V (See Figure 3).
Figure 5. RST Output Voltage
Characteristics of the Circuit in Figure 4
5
4
3
2
1
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
D1
V
10k PULL-UP FROM RST TO V
T
CC5
A
U
= 25 C
= V
5
4
3
2
D1: MMBD914 OR EQUIVALENT
CCA
V
V
V
GND
CC3
CC5
CCA
LTC1728-5
CC5
= 0V TO 5V
V
CC5
RST
(V)
LTC1727-2.5/LTC1728-2.5/LTC1728-1.8
Override Functions
The V
V
V
point for V
be tied to V
V
result in the continuous assertion of RST.
CC18
CC3
CC25
1
CC5
and V
CCA
. This is an obvious solution since the trip points for
/V
CC18
R1
10k
1727/28 F05
pin, if unused, can be tied to either V
CCA
CC25
CC3
and operating off of a 2.5V/1.8V supply will
TO SYSTEM
RESET
. Likewise, the V
. V
/V
1727/28 F04
CC3
CC18
must always be used. Tying V
will always be greater than the trip
LTC1727/LTC1728
CC25
/V
CC18
, if unused, can
CC3
or V
11
CC3
CC25
to
/