DEMO MANUAL DC1836A
LTC2955
Pushbutton On/Off Controller
with Automatic Turn-On
Description
Demonstration circuit 1836A-A and 1836A-B feature the
LTC
®
2955-1 and LTC2995-2, respectively. The LTC2955 is
a micropower, pushbutton on/off controller that manages
system power by generating a clean enable output from
the supply monitor input and the debounced pushbut-
ton input. It features an interrupt output that notifies the
system of a pushbutton event or low level at the ON pin.
When the system receives an
INT
signal, it may use the
power kill input to shut off power. If the pushbutton remains
pressed for more than the configurable turn-off duration
(3s or 32ms), the system power is forced off.
Design files for this circuit board are available at
http://www.linear.com/demo
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
BoarD photo
1.6V TO 36V SUPPLY
PULSE WAVE GENERATOR
I/O
dc1836a F01
Figure 1. Proper Test Equipment Setup
dc1836af
1
DEMO MANUAL DC1836A
harDware setup
JumPEr SETTingS
Tmr PEriOD:
Sets the amount of time the user has to
hold down the pushbutton in order to cause a shutdown
event. It can either be set to 32ms or 3 seconds.
On FunCTiOn:
Connect to ON BLOCKED to block the ON
pin falling edge from activating system turn-off. Connect
to ON ACTIVE to allow both the ON pin rising and falling
edges to activate system turn-on and turn-off, respectively.
Vin/On:
Connects or disconnects VIN from ON. Unless
external circuitry has been connected to ON, for ON to
function correctly, this should be set to ON.
KiLL:
Ties or separates
INT
from
KILL.
Set to TIE for au-
tomatic shutdown when a long press on the pushbutton
is detected.
LDO_in:
Chooses the input to the onboard LT3060 regula-
tor. The user can either set it to VIN to have it connected
to the VIN pin or EXTERNAL in order to have it driven by
the LDO_IN turret. See the Operating Principles section.
Only for LED/monitor circuitry.
EXTErnAL COnnECTiOnS
Signal connections are made via the row of turret posts
along the edges of the board.
gnD:
(3 turrets) These turrets are connected directly to
the ground planes.
Vin:
Connect a 1.6V to 36V power supply to this turret.
On:
Can be linked to VIN through the VIN/ON jumper, however,
can also be externally connected to a power source. Is con-
nected directly to the ON pin of the LTC2955. If the ON
function jumper is set to active, this pin can be used to turn
on the EN pin, or turn off the
EN
pin, depending on if the
demo board is populated with an LTC2955-1 or LTC2955-2.
PB:
This pin is already driven by the pushbutton, however,
if needed it can be driven by an external signal to simulate
a pushbutton press.
LDO_in:
Can be used to provide the LT3060 with power
when the LDO_IN jumper is set to external.
LDO_OuT:
Output from the LT3060. The state of this can
also be monitored at D1.
dc1836af
DigiTAL COnnECTiOnS
En/EN:
Active high (LTC2955-1), or active low (LTC2955-
2) signal. Should go active either on a valid ON signal or
with a debounced PB press.
INT:
Goes low on a pushbutton press when EN/EN is
active. Can be tied to KILL to turn off the part.
KILL:
A low signal at this input will disable EN/EN. The
TMR period jumper sets how long the input signal must
be held low.
PgD:
Power good output from the LTC2955. This pin
indicates the status of the ON pin in order to let the sys-
tem differentiate between pushbutton turn-on and supply
button turn-on events.
2
DEMO MANUAL DC1836A
operating principles
Connect a 1.6V to 36V power supply to VIN. If VIN is
less than 5.5V, set the LDO_IN jumper to EXTERNAL and
connect a 5.5V to 36V supply to the LDO_IN turret. The
LTC2955 will still operate with no power applied to LDO_IN,
but monitor LEDs will not function.
On the DC1836A, a pushbutton switch shorts the
PB
pin
to ground which in turn sets the
EN
pin low (DC1836A-B)
or the EN pin high (DC1836A-A). Shorting
PB
to ground
a second time and holding (duration depending on the
TMR_PERIOD jumper) subsequently de-asserts the
EN/EN pin. The EN/EN pin is unobtrusively monitored by
the LT6700 comparator.
An internal 512ms timer blanks (ignores) the
KILL
signal
during system power-up. This allows sufficient time for
the DC/DC converter and a controller to perform power-
up tasks.
A high to low transition on
PB
starts the turn-off sequence.
In order to assert
INT
low,
PB
must stay low continuously
for 32ms. Users can also force the system to power down
by holding the pushbutton down for a long period; this
period is set using the TMR_PERIOD jumper on the board.
After the EN/EN pin has been released, the LTC2955 starts
a one second lockout time. During this lockout time, the
PB
and ON inputs are ignored—this is meant to allow the
voltage regulator to turn off and for its output to decay to 0V.
PB
PB
EN
EN
dc1836a F02
dc1836a F03
Figure 2.
PB
going Low For 46.1ms, and En Pulling High,
Showing a Proper Turn-On Sequence
Figure 3.
PB
going Low for 28.6ms, and
EN
remaining High,
Showing Too Short of a
PB
Pulse to Properly Activate the Enable Pin
V
IN
EN
0N
PB
Figure 4. A Turn-On Sequence Where V
in
and On Activate En, as Opposed to PB.
notice the 924ms Delay Between V
in
going High and En Activating
dc1836a F04
dc1836af
3
DEMO MANUAL DC1836A
parts list
iTEm
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
1
2
3
4
1
2
3
4
QTY
0
1
0
1
1
1
1
1
13
5
5
2
1
1
1
2
1
0
1
1
1
4
2
1
1
2
2
1
2
0
1
1
2
0
1
U1
R17, R18
R15, R16
U1
R15, R16
R17, R18
rEFErEnCE
C1
C2
C3, C7
C4
C5
C6
C8
C9
E1-E13
JP1-JP5
XJP1-XJP5
D1, D2
D3
D4
R1
R2, R4
R3
R5, R7
R8
R9
R10
R11, R12, R13, R14
R6, R19
SW1
U3
U6, U7
PArT DESCriPTiOn
CAP OPT, 1206
.,
CAP X7R, 0.1µF 50V, 10%, 0805
.,
,
CAP OPT, 0603
.,
CAP X5R, 0.47µF 10V, 10%, 0603
.,
,
CAP X5R, 1µF 10V, 10%, 0603
.,
,
CAP X7R 10nF 10V, 10%, 0603
.,
CAP X5R, 2.2µF 10V, 10%, 0603
.,
,
CAP X5R, 0.1µF 10V, 10%, 0603
.,
,
TP TURRET, 0.064", PAD120-064
,
HD1×3-079
SHUNT
LED, GREEN
LED, RED
LED, AMBER
RES., CHIP 1k, 1/10W, 1%, 0603
,
RES., CHIP 200k, 1/16W, 1%, 0402
,
RES., CHIP 5.1k, 1/16W, 1%, 0402
,
RES., OPT., 0402
RES., CHIP 100k, 1/16W, 1%, 0402
,
RES., CHIP 845k, 1/16W, 1%, 0402
,
RES., CHIP 115k, 1/16W, 1%, 0402
,
RES., CHIP 475, 1/16W, 1%, 0402
,
RES., CHIP 10k, 1/16W, 1%, 0402
,
SWITCH, PUSHBUTTON
I.C., LT3060ETS8, TS8
I.C., LT6700CS6-1, SOT23-6
STENCIL TOP AND BOTTOM
I.C., LTC2955IDDB-1, DFN10DDB
Res., Chip, 100k, 1/16W, 1%, 0402
Res., OPT., 0402
FAB, PRINTED CIRCUIT BOARD
I.C., LTC2955IDDB-2, DFN10DDB
Res., Chip, 100k, 1/16W, 1%, 0402
Res., OPT., 0402
FAB, PRINTED CIRCUIT BOARD
DEMO CIRCUIT 1836A
DEMO CIRCUIT 1836A
LINEAR TECHNOLOGY, LTC2955IDDB-2
VISHAY, CRCW0402100KFKED
VISHAY, CRCW0402100KFKED
VISHAY, CRCW0402845KFKED
VISHAY, CRCW0402115KFKED
VISHAY, CRCW0402475RFKED
VISHAY, CRCW040210KFKED
PANASONIC, EVQPJS05K
LINEAR TECHNOLOGY, LT3060ETS8
LINEAR TECHNOLOGY, LT6700CS6-1
STENCIL, DC1836A
LINEAR TECHNOLOGY, LTC2955IDDB-1
VISHAY, CRCW0402100KFKED
TAIYO YUDEN, LMK107BJ474KA
AVX, 0603ZD105KAT2A
AVX, 0603ZC103KAT2A
MURATA, GRM188R61A225K
AVX, 0603ZD104KAT2A
MILL-MAX, 2308-2-00-80-00-00-07-0
SAMTEC, TMM103-02-L-S
SAMTEC, 2SN-BK-G
PANASONIC, LN1351-C-TR
PANASONIC, LN1251-C-TR
PANASONIC, LN1451-C-TR
VISHAY, CRCW06031K00FKEA
VISHAY, CRCW0402200KFKED
VISHAY, CRCW04025K10FKED
AVX, 08055C104KAT2A
mAnuFACTurEr/PArT numBEr
required Circuit Components
DC1836A-A required Circuit Components
DC1836A-B required Circuit Components
dc1836af
4
5
4
3
2
1
REVISION HISTORY
ECO
__
4
E11
VIN
U1
R1
1K
0603
C1
OPT
1206
PRODUCTION
VLADIMIR O.
04-13-12
REV
DESCRIPTION
APPROVED
DATE
E1
VIN
1.6V - 36V
E13
*
EN/EN
E6
D
D
GND
4
VIN
SEL
ON
PB
TMR
GND
11
TIE
SEPARATE
JP3
E5
LDO_OUT
E12
GND
R12
475
R13
475
0.1uF
KILL
EN/EN
INT
PGD
KILL
GND
1
2
3
6
R6
10K
R7
OPT
R8
100K
3
1
INT
E8
PGD
E9
KILL
E7
R5
OPT
VIN / ON
1
CON
2
3
DIS
JP5
R2
ON FUNCTION
1
ON ACTIVE
2
3
ON BLOCKED
JP1
R19
10K
C2
0.1uF
0805
7
10
2
9
*
E2
200K
C3
OPT
R4
200K
ON
5
8
E3
R3
5.1K
NO_PB
SW1
EVQPJS05K
PB
1
2
TMR PERIOD
3
32MS
2
1
3.0S
JP2
C4
0.47uF
schematic Diagram
LDO_OUT
C9
R11
475
C
EXTERNAL
VIN
1
LDO_IN
JP4
C7
OPT
R9
845K
C8
2.2uF
C
LDO_OUT
1
D1
GREEN
E10
1
2
3
LDO_IN
5
VIN
U3
LT3060ETS8
U6
LT6700CS6-1
R10
115K
PGD
D4
AMBER
1
INT
D3
RED
2
C5
1uF
GND
SHDN
OUTB
6
GND1
GND2
GND3 REF/BYP
8
C6
10nF
ADJ
-INB
2
3
4
3
GND
400mV
-
OUTA
+INA
+
-
+
1
2
2
E4
1
7
4
VS
5
IN
OUT
6
2
B
INSTALL FOR ENABLE (TRUE)
R15
R14
475
B
5
*
*
*
*
4
-INB
1
U7
LT6700CS6-1
EN / EN
VS
D2
GREEN
-
+
R16
EN/EN
OUTB
6
E6
100K
OPT
100K
R18
R17
R15,R16 R17,R18
OPT
*
INSTALL FOR ENABLE #
U1
ASSY
-A
LTC2955IDDB-1
EN
3
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
400mV
-
OUTA
+INA
+
1
GND
-B
LTC2955IDDB-2
EN
CUSTOMER NOTICE
2
APPROVALS
PCB DES.
LT
APP ENG. VLADIMIR O.
A
2
A
TECHNOLOGY
TITLE: SCHEMATIC
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
NOTE: UNLESS OTHERWISE SPECIFIED
PUSH BUTTON ON / OFF CONTROLLER WITH uP INTERRUPT
SIZE
IC NO.
REV.
1. ALL RESISTORS ARE IN OHMS, 0402.
ALL CAPACITORS ARE IN MICROFARADS, 0603.
4
N/A
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
3
LTC2955IDDB-1 / -2
DEMO CIRCUIT 1836A
SCALE = NONE
2
4
DATE:
Friday, April 13, 2012
1
SHEET 1
OF 1
5
DEMO MANUAL DC1836A
dc1836af
Figure 5. Pushbutton On/Off Controller with µP interrupt
5
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