LTC2935IDC-1#PBF Linear Technology, LTC2935IDC-1#PBF Datasheet - Page 8

• Manufacturer Part Number: LTC2935IDC-1#PBF
• Manufacturer: Linear Technology

Specifications of LTC2935IDC-1#PBF

• Voltage Supervisor Type: Voltage Monitor
• Number Of Voltage Supervisors: 1
• Operating Supply Voltage (max): 5.5V
• Operating Temperature Classification: Industrial
• Operating Temp Range: -40C to 85C
• Pin Count: 8
• Mounting: Surface Mount
• Lead Free Status / Rohs Status: Compliant

APPLICATIONS INFORMATION
LTC2935
Selecting Output Logic Style
The LTC2935 status outputs are available in two options:
open-drain (LTC2935-1) or active pull-up (LTC2935-2).
The open-drain option (LTC2935-1) allows the outputs
to be pulled up to a user defi ned voltage with a resistor.
The open-drain pull-up voltage may be greater than V
(5.5V maximum), which is not always possible with inferior
battery supervisors, due to internal clamps. When the
status outputs are low, power is dissipated in the pull-up
resistors. Recommended resistor values lie in the range
between 10k and 470k. Figure 1 demonstrates typical
LTC2935-1 RST output behavior.
The active pull-up option (LTC2935-2) eliminates the need
for external pull-up resistors on the status outputs. Inte-
grated pull-up devices pull the outputs up to V
pulled up outputs may not be driven above V
Some applications require the RST and/or PFO outputs to
be valid with V
this requirement with the addition of an external resistor
from the output to ground. The resistor provides a path
for leakage currents, preventing the output from fl oating to
undetermined voltages when connected to high impedance
8
Figure 1. RST vs V
3.5
3.0
2.0
1.5
1.0
2.5
0.5
0
CC
0
LTC2935-1
S2 = GND
S1 = S0 = V
down to ground. Active pull-up handles
0.5
CC
1
1.5
V
CC
CC
with 10k Pull-Up
(V)
2
2.5
3
2935 F01
3.5
CC
CC
.
. Actively
CC
(such as CMOS logic inputs). The resistor value should
be small enough to provide effective pull-down without
excessively loading the pull-up circuitry. A 100k resistor
from output to ground is satisfactory for most applications.
When the status outputs are high, power is dissipated in
the pull-down resistors. Figure 2 demonstrates typical
LTC2935-2 RST output behavior.
Manual Reset Input
When V
reset input (MR) is pulled low, the RST output is forced low.
RST remains low for 200ms after the manual reset input is
released and pulled high. The manual reset input is pulled
up internally through 900k to V
rents have the ability to pull down the manual reset input
below its logic threshold, a lower value pull-up resistor,
placed between V
Input MR is often pulled down through a pushbutton
switch requiring human contact. If extended ESD toler-
ance is required, series resistance between the switch and
the input is recommended. For most applications, a 10k
resistor provides suffi cient current limiting.
CC
3.0
2.0
3.5
2.5
1.5
1.0
0.5
is above its reset threshold, and the manual
0
0
LTC2935-2
S2 = GND
S1 = S0 = V
0.5
CC
Figure 2. RST vs V
and MR will fi x the problem.
CC
1
1.5
V
CC
(V)
2
CC
. If external leakage cur-
2.5
CC
3
2935 F02
3.5
2935f