LTC2966
13
2966fb
For more information www.linear.com/LTC2966
APPLICATIONS INFORMATION
current specifications. When the status outputs are low,
power is dissipated in the pull-up resistors. An internal
pull-up is present if the OUT pins are left floating or if
low power consumption is required. The internal pull-up
resistor does not draw current if an external resistor pulls
OUT up to a voltage greater than V
OH
.
If PS is connected to ground, the comparator output is
noninverting. This means that OUT pulls low when V
IN
falls below the scaled INL voltage. OUT is released after
V
IN
rises above the scaled INH voltage. Likewise, if PS
is connected to REF or a voltage >V
TH
, the comparator
output is inverting. This means that OUT pulls low when
V
IN
rises above the scaled INH voltage and is released
when V
IN
falls below the scaled INL voltage.
If both V
IN
pins fall below the UVLO threshold minus hys-
teresis, the outputs are pulled to ground. The outputs are
guaranteed to
stay low for V
INA
≥ V
INB
≥ 1.25V regardless
of the output logic configuration.
It is recommended that circuit board traces associated
with the OUT pin be located on a different layer than those
associated with the INH/INL and REF pins where possible
to avoid capacitive coupling.
Hot Swap Events
The LTC2966 can withstand high voltage transients up
to 140V. However, when a supply voltage is abruptly
connected to the input resonant ringing can occur as a
result of series inductance. The peak voltage could rise
to 2x the input supply, but in practice can reach 2.5x if
a capacitor with a strong voltage coefficient is present.
Circuit board trace inductances of as little as 10nH can
produce significant ringing. Ringing beyond the absolute
maximum specification can be destructive to the part and
should be avoided whenever possible. One effective means
to eliminate ringing seen at the V
IN
pins and to protect the
part is to include a 1kΩ to 5kΩ resistance between the
monitored voltage and the V
IN
pin as shown in Figure 6.
This provides damping for the resonant circuit. If there
is a decoupling capacitor on the V
INA
/V
INB
pins the time
constant formed by the RC network should be considered.
Figure 4. Reducing V
IN
Threshold Error
Figure 5. Disabling a Channel
Disabling a Channel
Figure 5 shows the proper technique for disabling a chan-
nel. T
able 4 summarizes the correct connections. Correctly
disabling an unused channel prevents its comparator
output from chattering and introducing unwanted noise
in the system.
Table 4. Disabling a Channel
PIN CONNECT TO
V
IN
GND
INH REF
INL GND
RS1 GND or REF
RS2 GND or REF
PS GND or REF
OUT Open
V
IN
V
IN
LTC2966
GND
REF
1µF
INH
INL
2966 F04
LT6656-2.048
OUT
R2
200k
0.1%
R1
1.8M
0.1%
R3
47.5k
0.1%
R4
10k
IN
GND
Output Configuration with Polarity Selection
The OUT pin may be used with a wide range of user-defined
voltages up to 100V with an external resistor. Select a
resistor compatible with desired output rise time and load
V
INA
GND
1/2 LTC2966
OPEN
REF
INHA
INLA
OUTA
RS1A
RS2A
PSA
OPEN
2966 F05
