LTC2951CDDB-2#TRPBF Linear Technology, LTC2951CDDB-2#TRPBF Datasheet - Page 11

• Manufacturer Part Number: LTC2951CDDB-2#TRPBF
• Description: IC PUSH BUTTON ON/OFF CTRLR 8DFN
• Manufacturer: Linear Technology

Specifications of LTC2951CDDB-2#TRPBF

• Applications: Push Button, On/Off Controller
• Voltage - Supply: 2.7 V ~ 26.4 V
• Current - Supply: 6µA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-DFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -

APPLICATIONS INFORMATION
Simplified Power-On/-Off Sequence
Figure 1 shows a simplified LTC2951-1 power-on and
power-off sequence. A high to low transition on PB (t
initiates the power-on sequence. This diagram does not
show any bounce on PB . In order to assert the enable
output, the PB pin must stay low continuously (PB high
resets timers) for 128ms (t
an internal 512ms blanking timer is started. This blank-
ing timer is designed to give sufficient time for the DC/
DC converter to reach its final voltage, and to allow the
µP enough time to perform power-on tasks.
The KILL pin must be pulled high within 512ms of the
EN pin going high. Failure to do so results in the EN
OFFT
KILL
INT
PB
EN
t
1
2
t
–t
DB, ON
1
). Once EN goes high (t
Figure 1. Simplified Power-On/-Off Sequence for LTC2951-1
t
2
PB & KILL IGNORED
t
KILL, ON BLANK
t
3
2
1
t
),
4
)
pin going low 512ms after it went high. (EN = low, see
Figure 2). Note that the LTC2951 does not sample KILL
and PB until after the 512ms internal timer has expired.
The reason PB is ignored is to ensure that the system
is not forced off while powering on. Once the 512ms
timer expires (t
debounced with an internal 32ms timer. The system has
now properly powered on and the LTC2951 monitors PB
and KILL (for a turnoff command) while consuming only
6µA of supply current.
A high to low transition on PB (t
sequence. PB must stay low continuously (PB high resets
debounce timer) for a period controlled by the default 32ms
t
5
t
DB, OFF
LTC2951-1/LTC2951-2
t
OFFT
4
), the release of the PB pin is then
t
6
PB IGNORED
OFF DELAY
< t
KILL,
t
7
5
) initiates the power-off
2951 F01
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