LTC2950CTS8-2#PBF Linear Technology, LTC2950CTS8-2#PBF Datasheet - Page 12

• Manufacturer Part Number: LTC2950CTS8-2#PBF
• Manufacturer: Linear Technology

Specifications of LTC2950CTS8-2#PBF

• Operating Temperature (max): 70C
• Operating Temperature (min): 0C
• Pin Count: 8
• Mounting: Surface Mount
• Package Type: TSOT-23
• Case Length: 2.9mm
• Screening Level: Commercial
• Lead Free Status / RoHS Status: Compliant

LTC2950-1/LTC2950-2
APPLICATIONS INFORMATION
Voltage Monitoring with KILL Input
The KILL pin can be used as a voltage monitor. Figure 5
shows an application where the KILL pin has a dual func-
tion. It is driven by a low leakage open drain output of the
μP . It is also connected to a resistor divider that monitors
battery voltage (V
low the set value, the voltage at the KILL pin falls below
0.6V and the EN pin is quickly pulled low. Note that the
resistor values should be as large as possible, but small
TYPICAL APPLICATIONS
12
The following equations describe the turn on and turn
off times. C
capacitors:
High Voltage Pins
The V
PB can, additionally, operate below ground (–6V) without
latching up the device. PB has an ESD HBM rating of ±10kV.
0.1μF
t
t
C4
BD,ON
BD,OFF
IN
V
Figure 5. Input Voltage Monitoring with KILL Input
IN
9V
and PB pins can operate at voltages up to 26.4V.
+ t
+ t
V
GND ONT
PB
5.4V THRESHOLD
ONT
IN
ONT
OFFT
LTC2950-1
and C
= 32ms + 1ms + (6.7x10
= 32ms + 1ms + (6.7x10
IN
C
0.033μF
). When the battery voltage falls be-
ONT
OFFT
*
OFFT
KILL
INT
EN
are the external programming
C
0.033μF
OFFT
806k
100k
1%
1%
R3
R2
*
*OPTIONAL
V
SHDN
IN
LT1767-3.3
R1
10k
6
6
V
) • C
) • C
OUT
INT
KILL
(OPEN DRAIN)
ONT
OFFT
μP
2950 F05
3.3V
If the push button switch connected to PB exhibits high
leakage current, then an external pull-up resistor to VIN is
recommended. Furthermore, if the push button switch is
physically located far from the LTC2950 PB pin, parasitic
capacitances may couple onto the high impedance PB
input. Additionally, parasitic series inductance may cause
unpredictable ringing at the PB pin. Placing a 5k resistor
from the PB pin to the push button switch would mitigate
parasitic inductance problems. Placing a 0.1μF capacitor
on the PB pin would lessen the impact of parasitic capaci-
tive coupling.
enough to keep leakage currents from tripping the 0.6V
KILL comparator.
The DC/DC converter shown has an internal pull-up current on
its SHDN pin. A pull-up resistor on EN is thus not needed.
Operation Without μP
Figure 6 shows how to connect the KILL pin when there
is no circuitry available to drive it. The minimum pulse
width detected is 30μs. If there are glitches on the resistor
0.1μF
C4
V
IN
9V
V
GND ONT
PB
IN
LTC2950-1
Figure 6. No μP Application
C
0.033μF
ONT
*
OFFT
KILL
INT
EN
C
0.033μF
OFFT
*
*OPTIONAL
V
SHDN
IN
LT1767-3.3
V
OUT
+
R1
100k
C3*
0.01μF
2950 F06
3.3V
295012fc