LTC2950 LINER [Linear Technology], LTC2950 Datasheet - Page 13

• Manufacturer Part Number: LTC2950
• Description: Push Button On/Off Controller
• Manufacturer: LINER [Linear Technology]

TYPICAL APPLICATIO S
Power Path Switching
The ⎯ E ⎯ N open drain output of the LTC2951-2 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 ⎯ P ⎯ B pin. Figure 7 shows the LTC2951-2
controlling a two cell Li-Ion battery application. The ⎯ I ⎯ N ⎯ T
and ⎯ K ⎯ I ⎯ L ⎯ L pins are connected to the output of the PFET
through a resistor divider. The ⎯ K ⎯ I ⎯ L ⎯ L pin serves as a voltage
monitor. When V
circuited 30µs later.
OUT
drops below 6V, the ⎯ E ⎯ N pin is open
Li-Ion BATTERY
Li-Ion BATTERY
SINGLE CELL
SINGLE CELL
4.2V
4.2V
PARASITICS
Figure 7. Power Path Control with 6V Under Voltage Detect
+
+
CERAMIC
U
0.1µF
NOISE
INDUCTANCE
C4
CAPACITANCE
TRACE
TRACE
Figure 8. Filtering for Noisy ⎯ P ⎯ B Traces
V
PB
GND
IN
KILLT
LTC2951-2
0.1µF
R6
C
0.033µF
5k
R5
100K
KILLT
C5
*
OFFT
KILL
INT
EN
V
⎯ P ⎯ B Pin in a Noisy Environment
The rugged ⎯ P ⎯ B pin is designed to operate in noisy envi-
ronments. Transients below ground (>–6V) and above V
(<33V) will not damage the rugged ⎯ P ⎯ B pin. Additionally,
the ⎯ P ⎯ B pin can withstand ESD HBM strikes up to ±10kV.
In order to keep external noise from coupling inside the
LTC2951, place an R-C network close to the ⎯ P ⎯ B pin. A
5k resistor and a 0.1µF capacitor should suffi ce for most
noisy applications (see Figure 8).
IN
OPEN DRAIN OUTPUT
C
0.033µF
V
OFFT
TH
V
PB
GND
IN
= 0.6V INPUT
*
DETAILS OMITTED
M1
*OPTIONAL
FOR CLARITY
LTC2951-1
KILLT
100k
OFFT
1%
KILL
R4
INT
EN
2951 F08
OPTIONAL GLITCH
FILTER CAPACITOR
R1
909k
1%
V
OUT
V
OUT
,TRIP POINT = 6V
C3*
0.1µF
2951 F07
LTC2951
13
2951f
IN