ltc2950-1 Linear Technology Corporation, ltc2950-1 Datasheet - Page 13

• Manufacturer Part Number: ltc2950-1
• Description: Push Button On/off Controller
• Manufacturer: Linear Technology Corporation

TYPICAL APPLICATIONS
pull-up voltage that are wider than 30μs and transition
below 0.6V, then an appropriate bypass capacitor should
be connected to the KILL pin.
Power Path 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
circuited 30μs later.
OUT
Li-Ion BATTERY
Li-Ion BATTERY
SINGLE CELL
SINGLE CELL
drops below 6V, the EN pin is open
4.2V
4.2V
+
+
PARASITICS
CERAMIC
Figure 7. Power Path Control with 6V Under Voltage Detect
0.1μF
C4
NOISE
INDUCTANCE
CAPACITANCE
TRACE
TRACE
GND ONT
V
PB
IN
Figure 8. Noisy PB Trace
LTC2950-2
C
0.033μF
R5
100K
ONT
0.1μF
R6
5k
C5
*
OFFT
KILL
INT
EN
V
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
(<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 suffi ce 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
C
0.033μF
OPEN DRAIN OUTPUT
V
IN
OFFT
TH
= 0.6V INPUT
GND
*
V
PB
IN
M1
*OPTIONAL
DETAILS OMITTED
FOR CLARITY
LTC2950-1
ONT
LTC2950-1/LTC2950-2
100k
1%
R4
OFFT
KILL
INT
EN
R1
909k
1%
OPTIONAL GLITCH
FILTER CAPACITOR
2950 F08
V
OUT
V
OUT
,TRIP POINT = 6V
C3*
0.1μF
2950 F07
13
295012fc
IN