manages system power via a push button interface. An
enable output toggles system power while an interrupt
output provides debounced push button status. The inter-
rupt output can be used in menu driven applications to
request a system power down. A power kill input allows
a microprocessor or system to reset the enable output,
effectively powering down the system. Independently ad-
justable On and Off timers allow dependable push button
control of the enable output and resistance to accidental
toggling of system power.
The LTC2954 operates over a wide 2.7V to 26.4V input
voltage range to accommodate a wide variety of input power
supplies. Very low quiescent current (6µA typical) makes
the LTC2954 ideally suited for battery powered applications.
Two versions of the part are available to accommodate
either positive or negative enable polarities.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
APPLICATIO S
■
■
■
■
■
Push Button Power Path Control
Portable Instrumentation Meters
Blade Servers
Portable Customer Service PDA
Desktop and Notebook Computers
+
9V
100k
V
IN
LTC2954-2
PB
GND
ONT
EN
INT
KILL
PDT
1µF
t
PDT
= 6.4 SECONDS
U
TYPICAL APPLICATIO
U
Push Button On/Off with Interrupt
V
IN
V
OUT
DC/DC
100k
PB
TURN ON PULSE
EN
10k
INT
KILL
µP/µC
INT
TURNS ON
2954f
1
LTC2954
(Note 1)
Supply Voltage (V
IN
) ..................................– 0.3V to 33V
Input Voltages
P
B ............................................................– 6V to 33V
ONT ......................................................– 0.3V to 2.7V
PDT.......................................................– 0.3V to 2.7V
K
I
L
L .........................................................– 0.3V to 7V
Output Voltages
I
N
T .........................................................– 0.3V to 10V
EN/
E
N ....................................................– 0.3V to 33V
TOP VIEW
GND 1
ONT 2
PB 3
V
IN
4
9
8
7
6
5
INT
EN/EN
PDT
KILL
TOP VIEW
V
IN
1
PB 2
ONT 3
GND 4
8 KILL
7 PDT
6 EN/EN
5 INT
DDB PACKAGE
8-LEAD (3mm
×
2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 165°C/W
EXPOSED PAD (PIN 9) UNCONNECTED
ORDER PART NUMBER
LTC2954CDDB-1
LTC2954CDDB-2
LTC2954IDDB-1
LTC2954IDDB-2
DDB PART MARKING*
LCJG
LCNJ
LCJG
LCNJ
Order Options
Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
I
IN
V
UVL
V
UVL(HYST)
PARAMETER
Supply Voltage Range
V
IN
Supply Current
V
IN
Undervoltage Lockout
V
IN
Undervoltage Lockout
Hysteresis
P
B Voltage Range
The
●
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)
CONDITIONS
Steady State Operation
System Power On, V
IN
= 2.7V to 24V
V
IN
Falling
●
●
●
Push Button, Enable (
P
B, EN/
E
N))
V
P
B(MIN, MAX)
Single-Ended
●
2
U
PACKAGE/ORDER I FOR ATIO
W
U
U
W W
W
ABSOLUTE
AXI U RATI GS
Operating Temperature Range
LTC2954C-1 .............................................. 0°C to 70°C
LTC2954C-2 .............................................. 0°C to 70°C
LTC2954I-1 .......................................... – 40°C to 85°C
LTC2954I-2 .......................................... – 40°C to 85°C
Storage Temperature Range
DFN Package..................................... – 65°C to 125°C
TSOT-23............................................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 140°C/W
ORDER PART NUMBER
LTC2954CTS8-1
LTC2954CTS8-2
LTC2954ITS8-1
LTC2954ITS8-2
TS8 PART MARKING*
LTCJH
LTCNK
LTCJH
LTCNK
MIN
2.7
TYP
6
MAX
26.4
12
2.5
700
UNITS
V
µA
V
mV
2.2
50
2.3
400
–1
26.4
V
2954f
LTC2954
ELECTRICAL CHARACTERISTICS
SYMBOL
I
P
B
PARAMETER
P
B Input Current
The
●
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)
CONDITIONS
2.5V < V
P
B
< 26.4V
V
P
B
= 1V
V
P
B
= 0.6V
P
B Falling
I
P
B
= –1µA
Enable Released
→
Enable Asserted
V
EN/
E
N
= 1V, Sink Current Off
V
EN/
E
N
= 26.4V, Sink Current Off
I
EN/
E
N
= 500µA
V
ONT
= 0V
V
ONT
= 1.3V
ONT Pin Float,
P
B Falling
→
Enable Asserted
●
●
●
●
●
●
●
●
MIN
–1
–3
0.6
1
200
TYP
–6
–9
0.8
1.6
256
MAX
±1
–12
–15
1
2
325
±0.1
±1
UNITS
µA
µA
µA
V
V
ms
µA
µA
V
µA
µA
ms
ms
µA
µA
ms
ms
ms
ms
ms
µA
V
V
mV
µA
µs
µs
ms
V
P
B(VTH)
V
P
B(VOC)
t
EN, Lock Out
I
EN(LKG)
V
EN(VOL)
I
ONT(PU)
I
ONT(PD)
t
DB, ON
t
ONT
P
B Input Threshold
P
B Open Circuit Voltage
EN/E
N Lock Out Time (Note 5)
EN/
E
N Leakage Current
EN/
E
N Voltage Output Low
ONT Pull Up Current
ONT Pull Down Current
Internal Turn On Debounce Time
0.11
–2.4
2.4
26
9
–2.4
2.4
26
52
9
26
35
–3
3
32
11.5
–3
3
32
64
11.5
32
43.5
0.4
–3.6
3.6
41
13.5
–3.6
3.6
41
82
13.5
41
54.5
±1
Power On Timing Pin (ONT)
●
●
●
●
Additional Adjustable Turn On Time C
ONT
= 1500pF
Power Down Timing Pin (PDT)
I
PDT(PU)
I
PDT(PD)
t
DB, OFF
t
PD, Min
t
PDT
t
I
N
T, Min
t
I
N
T, Max
I
I
N
T(LKG)
V
I
N
T(VOL)
V
K
I
L
L(TH)
V
K
I
L
L(HYST)
I
K
I
L
L(LKG)
t
K
I
L
L(PW)
t
K
I
L
L(PD)
t
K
I
L
L, On Blank
PDT Pull Up Current
PDT Pull Down Current
Turn Off Interrupt Debounce Time
Internal
P
B Power Down
DebounceTime (Note 4)
Additional Adjustable
P
B Power
Down Debounce Time
Minimum
I
N
T Pulse Width
Maximum
I
N
T Pulse Width
I
N
T Leakage Current
I
N
T Output Voltage Low
K
I
L
L Input Threshold Voltage
K
I
L
L Input Threshold Hysteresis
K
I
L
L Leakage Current
K
I
L
L Minimum Pulse Width
K
I
L
L Propagation Delay
K
I
L
L Turn On Blanking (Note 3)
K
I
L
L Falling
→
Enable Released
K
I
L
L = Low, Enable Asserted
→
Enable Released
V
K
I
L
L
= 0.6V
V
PDT
= 0V
V
PDT
= 1.3V
P
B Falling
→
I
N
T Falling
PDT Pin Float,
P
B Falling
→
Enable Released
C
PDT
= 1500pF
IN
T Asserted
→
I
N
T Released
C
PDT
= 1500pF,
I
N
T Asserted
→
I
N
T Released
V
I
N
T
= 3V
I
I
N
T
= 3mA
K
I
L
L Falling
●
●
●
●
●
●
●
µP Handshake Pins (
I
N
T,
K
I
L
L)
●
●
●
●
●
●
●
●
0.11
0.57
10
30
0.6
30
0.4
0.63
50
±0.1
30
400
512
650
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
or t
ONT
.
Note 4:
To manually force an immediate release of the EN/
E
N pin, the push
button input must be held low for at least t
PD,Min
(internal default power
down timer) + t
PDT
(adjustable by placing external capacitor at PDT pin).
Note 5:
The enable lock out time is designed to allow an application to
properly power down such that the next power up sequence starts from a
语音作为自然的人机接口，可以使车载导航系统实现更安全、更人性化的操作。通过国内外车载导航系统的功能对比可知，支持语音交互是车载导航系统的一个发展趋势。另外，市场信息服务公司J.D Power and Associates的调研数据也表明，56％的消费者更倾向于选择声控的导航系统。因此，开发车载语音导航系统是很有意义的。目前，国内已经具备开发车载语音导航系统的技术基础，特别是文语转换TTS技术...[详细]
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