LTC2950-1/LTC2950-2
13
295012fd
below 0.6V, then an appropriate bypass capacitor should
be connected to the KILL pin.
PowerPath™ Switching
The EN open drain output of the LTC2950-2 is designed to
switch on/off an external power PFET. This allows a user
to connect/disconnect a power supply (or battery) to its
load by toggling the PB pin. Figure 7 shows the LTC2950-2
controlling a two cell Li-Ion battery application. The INT
and KILL pins are connected to the output of the PFET
through a resistor divider. The KILL pin serves as a voltage
monitor. When V
OUT
drops below 6V, the EN pin is open
circuited 30µs later.
V
OUT
R1
909k
1%
R4
100k
1%
C3*
0.1µF
2950 F07
C4
0.1µF
CERAMIC
*OPTIONAL
OPEN DRAIN OUTPUT
V
TH
= 0.6V INPUT
R5
100K
M1
+
4.2V
SINGLE CELL
Li-Ion BATTERY
+
4.2V
SINGLE CELL
Li-Ion BATTERY
OPTIONAL GLITCH
FILTER CAPACITOR
V
OUT
,TRIP POINT = 6V
PB
EN
INT
KILL
LTC2950-2
GND ONT OFFT
V
IN
C
ONT
*
0.033µF
C
OFFT
*
0.033µF
PB
V
IN
LTC2950-1
GND ONT
R6
5k
2950 F08
TRACE
CAPACITANCE
PARASITICS
C5
0.1µF
DETAILS OMITTED
FOR CLARITY
TRACE
INDUCTANCE
NOISE
EN
INT
KILL
OFFT
V
IN
Figure 7. PowerPath Control with 6V Undervoltage Detect
Figure 8. Noisy PB Trace
PB Pin in a Noisy Environment
The rugged PB pin is designed to operate in noisy envi-
ronments. Transients below ground (>–6V) and above V
IN
(<30V) will not damage the rugged PB pin. Additionally,
the PB pin can withstand ESD HBM strikes up to ±10kV.
In order to keep external noise from coupling inside the
LTC2950, place an R-C network close to the PB pin. A 5k
resistor and a 0.1µF capacitor should suffice for most
noisy applications (see Figure 8).
External Pull-Up Resistor on PB
An internal pull-up resistor on the PB pin makes an ex-
ternal pull-up resistor unnecessary. Leakage current on
Typical applicaTions
