Datasheet

LTC2951-1/LTC2951-2
3
295112fb
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 2.7V to 26.4V, unless otherwise noted. (Note 2)
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
Note 3: The KILL turn-on blanking timer period is the waiting period
immediately after the enable output is asserted. This blanking time allows
sufficient time for the DC/DC converter and the µP to perform power-up
tasks. The KILL and PB inputs are ignored during this period. If KILL
remains low at the end of this time period, the enable output is released,
thus turning off system power. This time delay does not include t
DB,ON
.
Note 4: The internal KILL turn-off delay (t
KILL
,
OFF DELAY
) is the default
delay from the initiation of a power-off sequence (INT falling, KILL = high),
to the release of the enable output. The additional, adjustable KILL turn-off
delay (t
KILL
,
OFF DELAY, ADDITIONAL
) uses an optional external capacitor
(C
KILLT
) to provide extra delay from INT falling to the release of the enable
output. If the KILL input switches low at any time during KILL turn-off
delay, enable is released, thus turning off system power.
Note 5: The enable lockout time is designed to allow an application to
properly power down such that the next power-up sequence starts from a
consistent powered down configuration. PB is ignored during this lockout
time. This time delay does not include t
DB, ON
.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Supply Voltage Range Steady-State Operation
l
2.7 26.4 V
I
IN
V
IN
Supply Current System Power-On, V
IN
= 2.7V to 24V
l
6 12 µA
V
UVL
V
IN
Undervoltage Lockout V
IN
Falling
l
2.2 2.3 2.4 V
V
UVL(HYST)
V
IN
Undervoltage Lockout Hysteresis
l
50 300 600 mV
Pushbutton, Enable (PB, EN/ EN)
V
PB(MIN, MAX)
PB Voltage Range Single-Ended
l
–1 26.4 V
I
PB
PB Input Current 2.5V < V
PB
< 26.4V
V
PB
= 1V
V
PB
= 0.6V
l
l
l
–1
–3
–6
–9
±1
–12
–15
µA
µA
µA
V
PB(VTH)
PB Input Threshold PB Falling
l
0.6 0.8 1 V
t
EN/EN, Lockout
EN/EN Lockout Time (Note 5)
Enable Released → Enable Asserted
l
200 256 325 ms
I
EN/EN(LKG)
EN/EN Leakage Current V
EN/EN
= 1V, Sink Current Off
l
±0.1 µA
V
EN/EN(VOL)
EN/EN Voltage Output Low I
EN/EN
= 3mA
l
0.11 0.4 V
V
PB(VOC)
PB Open-Circuit Voltage I
PB
= –1µA
l
1 1.6 2 V
Timing Pins (KILLT, OFFT)
I
KILLT, OFFT(PU)
KILLT/OFFT Pull-Up Current V
KILLT, OFFT
= 0V
l
–2.4 –3 –3.6 µA
I
KILLT, OFFT(PD)
KILLT/OFFT Pull-Down Current V
KILLT, OFFT
= 1.3V
l
2.4 3 3.6 µA
t
DB, ON
Turn-On Debounce Time
PB Falling → Enable Asserted
l
100 128 163 ms
t
DB, OFF
Internal Turn-Off Debounce Time
OFFT Pin Float, PB Falling → INT Falling
l
26 32 41 ms
t
OFFT
Additional Adjustable Turn-Off Time C
OFFT
= 1500pF
l
9 11.5 13.5 ms
µP Handshake Pins (INT, KILL)
I
INT(LKG)
INT Leakage Current V
INT
= 3V
l
±1 µA
V
INT(VOL)
INT Output Voltage Low I
INT
= 3mA
l
0.11 0.4 V
V
KILL(TH)
KILL Input Threshold Voltage KILL Falling
l
0.57 0.6 0.63 V
V
KILL(HYST)
KILL Input Threshold Hysteresis
l
10 30 50 mV
I
KILL(LKG)
KILL Leakage Current V
KILL
= 0.6V
l
±0.1 µA
t
KILL(PW)
KILL Minimum Pulse Width
l
30 µs
t
KILL(PD)
KILL Propagation Delay
KILL Falling → Enable Released
l
30 µs
t
KILL, ON BLANK
KILL Turn-On Blanking (Note 3)
KILL = Low, Enable Asserted → Enable Released
l
400 512 650 ms
t
KILL, OFF DELAY
Internal KILL Turn-Off Delay (Note 4)
KILLT Pin Float, KILL = High, INT Asserted →
Enable Released
l
100 128 163 ms
t
KILL,OFF DELAY,
ADDITIONAL
Additional Adjustable KILL Turn-Off Delay
(Note 4)
C
KILLT
= 1500pF
l
9 11.5 13.5 ms