Linear Technology LTC2950-2 User manual

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DEMO MANUAL
DC826C-A/DC826C-B
DESCRIPTION
LTC2950-2/LTC2951-2
Pushbutton On/Off Controller
Demonstration circuits 826C-A and 826C-B feature the
LT C
®
2950-2 and the LTC2951-2 respectively, which are
low power, wide input voltage range, pushbutton on/off
controllers. A pushbutton switch shorts the PB pin to
ground which in turn sets the EN pin low (see Note1).
Shorting PB to ground a second time subsequently resets
the EN pin high. The EN pin is used to connect to a DC/
DC converter shutdown to control the turn on and off of
the circuit, simulated with a green LED on the DC826C-A/
DC826C-B.
JP1 and JP2 on the DC826C-A provide the selection
of timing options for the PB on and off times. For the
DC826C-B, JP1 selects KILL times while JP2 selects off
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.
IC SELECTION GUIDE
times. JP3 ties and unties KILL to INT for immediate or
delayed turn off. The INT status is shown with a red LED.
DC826C-A/DC826C-B accepts an input voltage range of
2.7V to 26.4V or a 9V battery for portable demonstration
and evaluation.
Note 1: The inversion of EN of the LTC2950-2/LTC2951-2
is found in the LTC2950-1/LTC2951-1. Table 1 provides
an IC selection guide.
Design files for this circuit board are available at
http://www.linear.com/demo/DC826C
Table 1. LTC2950/LTC2951 Selection Guide (Typical Timing Values, Cap. Adjust = 212ms on DC826C-A/DC826C-B)
PART ENABLE ONT OFFT KILLT DEMO BOARD
LTC2950-1 EN 32ms + Cap. Adjust* 32ms + Cap. Adjust* 1000ms N/A
LTC2950-2 EN 32ms + Cap. Adjust* 32ms + Cap. Adjust* 1000ms DC826C-A
LTC2951-1 EN 128ms 32ms + Cap. Adjust* 128ms + Cap. Adjust* N/A
LTC2951-2 EN 128ms 32ms + Cap. Adjust* 128ms + Cap. Adjust* DC826C-B
*The additional Cap. Adjust time is selected by an external capacitor. The DC826C-A and DC826C-B adjust times have been pre-selected with a 0.033μF
capacitor to provide an additional 212ms. The additional time is calculated with the following equations as shown in the LTC2950/LTC2951 data sheets:
CONT = 1.56e-4 [μF/ms] • (tONT – 1ms)
COFFT = 1.56e-4 [μF/ms] • (tOFFT – 1ms)
CKILLT = 1.56e-4 [μF/ms] • (tKILL, OFF DELAY, ADDITIONAL – 1ms)

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DEMO MANUAL
DC826C-A/DC826C-B
QUICK START PROCEDURE
Demonstration circuit 826C-A/826C-B is easy to set up to
evaluate the performance of the LTC2950-2/LTC2951-2:
1. Place jumpers in the following positions:
JP1: 0.033μF
JP2: 0.033μF
JP3: UNTIE
The duration that PB must be shorted to ground in order
to turn on/off the DC/DC converter is independently pro-
grammed (LTC2950-2) by two external capacitors C1 and
C2 and selected on the DC826C-A with jumper JP1 and
JP2. The status of the EN pin, and simulation of the turn
on/off of a DC/DC converter, is displayed with green LED
D2 on the board.
Figure 1 shows how the EN is connected to the SHDN pin
of a DC/DC converter and how INT and KILL interfaces with
aµP or µC. An internal 500ms timer blanks (ignores) the
KILL signal during system power up. This allows sufficient
time for the DC/DC converter and a µP to perform power
up tasks. During turn off, a power down timer provides
a delay (LTC2950-2: 1000ms, LTC2951-2: adjustable)
from interrupting the µP(INT = low) to turning off the DC/
DC converter (EN = high). This delay gives the µP time
to perform power down and housekeeping tasks. On the
DC826C-B, JP1 selects the power down timer, while JP2
is used to adjust the turn off PB duration. The red LED
D1 shows the state of the INT pin. A µP can turn off the
converter with no delay by asserting KILL low. By tying
KILL to INT through JP3, KILL is forced low during the
INT blanking time and thus forces a turn off.
The RC (RRPP and CRPP) at VIN on the DC826 provides
reversepolarityprotectiontotheLTC2950-2/LTC2951-2.If
power is connected in an application such that the polari-
ties are ensured to be in the correct configuration, this RC
may be removed from the circuit.
An additional RC (RF and CF), located at the PB pin, acts
as a filter and is used in an application where the switch
is located far from the LTC2950-2/LTC2951-2. In such a
case, the RC would be placed next to the switch rather
than the part. If the switch is located near the LTC2950-2/
LTC2951-2, then the RC may be removed from the circuit.
An LDO (U2) is used on the DC826 to provide a pull-up
voltage of 2.6V which is well below the absolute maximum
on the INT, EN, and KILL pins for the full range of input
voltage of 2.7V to 26.4V. In an application, pull these
pins up to a voltage no higher than their rated absolute
maximum shown in the data sheet. Optional Zener diodes
(D3 – D5) can be used if the pull-up voltage exceeds the
rated absolute maximum. (If the interface pins on the
DC826C-A /DC826C-B will be pulled up to an external
supply, LEDs D1 and D2 should be removed.)
2. Connect the input power supply of 2.7V to 26.4V across
VIN and GND or a 9V battery to the battery connector.
3. Push and hold the pushbutton once to turn on the green
LED.
4. Push and hold the pushbutton again to turn off the
green LED.
OPERATING PRINCIPLES

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dc826cf
DEMO MANUAL
DC826C-A/DC826C-B
Figure1. DC826C-A/DC826C-B Example Setup
PUSHBUTTON
VIN
SHDN
VIN
VOUT
INT
KILL
DC/DC
BUCK
µP/µC
2.7V TO 26.4
OR
9V BATTERY
R1
10k
DC826C F01
OPERATING PRINCIPLES

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DEMO MANUAL
DC826C-A/DC826C-B
SCHEMATIC DIAGRAM
A A
B B
C C
D D
E E
4 4 3 3 2 2 1 1
SEE NOTE #1
NOTE 1. EN, the inverse of EN, is available in the LTC2950-1/LTC2951-1.
VIN
2.6V
VIN 2.6V
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APP ENG.
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CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
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APP ENG.
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CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
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IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
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CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
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REVISION HISTORY
DESCRIPTION DATE
APPROVED
ECO REV
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APPROVED
ECO REV
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DESCRIPTION DATE
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TP5
KILL
TP5
KILL
S1
ON/OFF
S1
ON/OFF
D5 11V (Opt) D5 11V (Opt) TP6
GND TP6 GND
C2 0.033uF C2 0.033uF
R4 113k
1%
R4 113k
1%
C4
0.47uF
10V C4
0.47uF
10V
TP7
GND
TP7
GND
JP2
0.033uF
OPEN
OFFT
JP2
0.033uF
OPEN
OFFT
1 3 2
RRPP
1k
RRPP
1k
D1 RED 2V
INT
D1 RED 2V
INT
RED BLK
KEYSTONE #232
RED BLK
KEYSTONE #232
R5
100k 1%
R5
100k 1%
JP1
0.033uF
OPEN
ONT/KILLT
JP1
0.033uF
OPEN
ONT/KILLT
1 3 2
R1
100
R1
100
TP1
VIN
2.7V-26.4V
TP1
VIN
2.7V-26.4V
D3 11V (Opt) D3 11V (Opt)
D4 11V (Opt) D4 11V (Opt)
CRPP
0.1uF 50V
CRPP
0.1uF 50V
TP4
PB
TP4
PB
TP2
INT
TP2
INT
TP3
EN
TP3
EN
U2 LT3014BES5 U2 LT3014BES5
NC
3
GND
2
IN
1OUT 5
ADJ 4
R3
100k
R3
100k
JP3
TIE
UNTIE
INT/KILL
JP3
TIE
UNTIE
INT/KILL
1 3 2
D2 GRN EN 2V D2 GRN EN 2V
R2
100
R2
100
U1 LTC2950CTS8-2 U1 LTC2950CTS8-2
GND
4
INT 5
PB
2
KILL 8
ONT/KILLT
3
EN 6
VIN
1
OFFT
7
RF
5.1k
RF
5.1k
C1
0.033uF
C1
0.033uF
CF
0.1uF 50V
CF
0.1uF 50V

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dc826cf
DEMO MANUAL
DC826C-A/DC826C-B
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.
SCHEMATIC DIAGRAM
A
A
B
B
C
C
D
D
E
E
4 4 3 3 2 2 1 1
SEE NOTE #1
NOTE 1. EN, the inverse of EN, is available in the LTC2950-1/LTC2951-1.
VIN
2.6V
VIN 2.6V
SIZE MODIFY DATE:
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TITLE:
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APP ENG.
TECHNOLOGY
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CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
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TITLE:
APPROVALS
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APP ENG.
TECHNOLOGY
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CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
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APP ENG.
TECHNOLOGY
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CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
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Dilian Reyes
C:\PADS PROJECTS\826C-B\SCH\826C-B_REV1.DSN
REVISION HISTORY
DESCRIPTION DATE
APPROVED
ECO REV
Dilian ReyesPRODUCTION(Replaced S1, D1 & D2)

C
Jan 27, 2014
REVISION HISTORY
DESCRIPTION DATE
APPROVED
ECO REV
Dilian ReyesPRODUCTION(Replaced S1, D1 & D2)

C
Jan 27, 2014
REVISION HISTORY
DESCRIPTION DATE
APPROVED
ECO REV
Dilian ReyesPRODUCTION(Replaced S1, D1 & D2)

C
Jan 27, 2014
TP5
KILL
TP5
KILL
S1
ON/OFF
S1
ON/OFF
D5 11V (Opt) D5 11V (Opt) TP6
GND TP6 GND
C2 0.033uF C2 0.033uF
R4 113k
1%
R4 113k
1%
C4
0.47uF
10V C4
0.47uF
10V
TP7
GND
TP7
GND
JP2
0.033uF
OPEN
OFFT
JP2
0.033uF
OPEN
OFFT
1 3 2
RRPP
1k
RRPP
1k
D1 RED 2V
INT
D1 RED 2V
INT
RED BLK
KEYSTONE #232
RED BLK
KEYSTONE #232
R5
100k 1%
R5
100k 1%
JP1
0.033uF
OPEN
ONT/KILLT
JP1
0.033uF
OPEN
ONT/KILLT
1 3 2
R1
100
R1
100
TP1
VIN
2.7V-26.4V
TP1
VIN
2.7V-26.4V
D3 11V (Opt) D3 11V (Opt)
D4 11V (Opt) D4 11V (Opt)
CRPP
0.1uF 50V
CRPP
0.1uF 50V
TP4
PB
TP4
PB
TP2
INT
TP2
INT
TP3
EN
TP3
EN
U2 LT3014BES5 U2 LT3014BES5
NC
3
GND
2
IN
1OUT 5
ADJ 4
R3
100k
R3
100k
JP3
TIE
UNTIE
INT/KILL
JP3
TIE
UNTIE
INT/KILL
1 3 2
D2 GRN EN 2V D2 GRN EN 2V
R2
100
R2
100
U1 LTC2951CTS8-2 U1 LTC2951CTS8-2
GND
4
INT 5
PB
2
KILL 8
ONT/KILLT
3
EN 6
VIN
1
OFFT
7
RF
5.1k
RF
5.1k
C1
0.033uF
C1
0.033uF
CF
0.1uF 50V
CF
0.1uF 50V

6
dc826cf
DEMO MANUAL
DC826C-A/DC826C-B
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2015
LT 0815 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application
engineer.
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Linear Technology
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Copyright © 2004, Linear Technology Corporation