LTC2907 LINER [Linear Technology], LTC2907 Datasheet - Page 9

• Manufacturer Part Number: LTC2907
• Description: 36V Nano-Current Two Input Voltage Monitor
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
The closest 1% resistor value is 34k. R3 is easily obtained
from:
The closest 1% resistor value is 7.5MΩ. Plugging the
standard values back into the equations yields the design
values for the falling reset and IN
Figure 2 demonstrates how the inputs can be biased
to monitor two voltages (V1, V2). In this example, four
resistors are required. Calculate each divider ratio for the
desired falling threshold (V
In Figure 2, OUT is tied back to the MR input, making the
state of the RST output dependent upon both V1 and V2. If
V1 and V2 are both above the configured falling threshold
plus hysteresis, RST is allowed to pull high. If independent
operation of the status outputs is desired, simply omit the
OUT and MR connection.
SELECTING OUTPUT LOGIC STYLE
The LTC2960 status outputs are available in two options:
open-drain (LTC2960-1/LTC2960-2) or active pull-up with
the DV
The open-drain option allows the outputs to be pulled up
R3 = R
R3 = 7.467MΩ
V
RnB
RnA
IN +
CC
= 6.4V, V
=
pin replacing the RT pin (LTC2960-3/LTC2960-4).
V1
V2
SUM
V
V
FT
TH
Figure 2. Dual Voltage Monitoring
– R1 – R2 = 8M – 499k – 34k
– 1=
RST
R2B
R2A
= 6.028V
0.4V
R1B
R1A
V
FT
ADJ
IN
FT
– 1
+
LTC2960-1/
LTC2960-3
) using:
MR
+
voltages:
OUT
RST
2960 F02
to a user defined voltage up to 36V with a resistor. The
open-drain pull-up voltage may be greater than V
a resistor compatible with desired output rise time and
load current specifications. Figure 3 demonstrates typical
LTC2960-1 OUT output behavior. When the status outputs
are low, power is dissipated in the pull-up resistors.
The outputs of both the LTC2960-3 and LTC2960-4 can be
configured as either low voltage active pull-up or open-
drain. This is done by tying the DV
or GND. Using the active pull-up configuration, DV
to a supply, lowers power dissipation by eliminating the
static current drawn by pull-up resistors when the outputs
are low and improves output rise time. In Figure 4(a), an
LTC2960-3 has active pull-up outputs configured by tying
DV
has open-drain outputs configured by tying the DV
ground. When DV
are open-drain and pull-up resistors are required.
Some applications require RST and/or OUT outputs to
be valid with V
V
dition of an optional external resistor from the output to
ground. The resistor provides a path for leakage currents,
preventing the output from floating to undetermined volt-
ages when connected to high impedance (such as CMOS
logic inputs). The resistor value should be small enough to
Figure 3. OUT vs V
Threshold with RST Tied to V
CC
CC
. Active pull-up satisfies this requirement with the ad-
to a 1.6V to 5.5V supply. In Figure 4(b), the LTC2960-3
7.5
4.5
1.5
6
3
0
0
CC
CC
CC
down to ground when DV
(LTC2960-1) Externally Configured for 6V
1.5
is connected to ground both outputs
CC
3
V
CC
Through Pull-up Resistor
(V)
4.5
CC
pin to either a supply
6
LTC2960
2960 F03
7.5
CC
CC
is tied to
CC
. Select
CC
pin to
9
tied
2960f