DEMO MANUAL DC826C-A/DC826C-B LTC2950-2/LTC2951-2 Pushbutton On/Off Controller DESCRIPTION Demonstration circuits 826C-A and 826C-B feature the LTC®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 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 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 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) dc826cf 1 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: 2.Connect the input power supply of 2.7V to 26.4V across VIN and GND or a 9V battery to the battery connector. 1.Place jumpers in the following positions: 3.Push and hold the pushbutton once to turn on the green LED. JP1:0.033μF JP2:0.033μF JP3:UNTIE 4.Push and hold the pushbutton again to turn off the green LED. OPERATING PRINCIPLES The duration that PB must be shorted to ground in order to turn on/off the DC/DC converter is independently programmed (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 a µP 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. 2 The RC (RRPP and CRPP) at VIN on the DC826 provides reverse polarity protection to the LTC2950-2/LTC2951‑2. If power is connected in an application such that the polarities 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.) dc826cf DEMO MANUAL DC826C-A/DC826C-B OPERATING PRINCIPLES PUSHBUTTON VIN VOUT DC/DC BUCK VIN 2.7V TO 26.4 OR 9V BATTERY SHDN R1 10k INT µP/µC KILL DC826C F01 Figure 1. DC826C-A/DC826C-B Example Setup dc826cf 3 1 2 3 4 BLK GND TP7 TP4 S1 ON/OFF 5.1k RF 1k VIN 2.7V-26.4V PB RRPP VIN TP1 CF 0.1uF 50V CRPP 0.1uF 50V A B 1 JP1 OPEN VIN CUSTOMER NOTICE JP2 C2 0.033uF 0.033uF D3 11V (Opt) SEE NOTE #1 3 1 NC IN C:\PADS PROJECTS\826C-A\SCH\826C-A_REV1.DSN THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. C D1 RED 2V INT R1 100 ADJ 4 5 UNTIE PCB DES. SCALE = NONE D APP ENG. Dilian Reyes R5 100k 1% R4 113k 1% 2.6V IC NO. E SHEET 1 OF 1 1 REV. MODIFY DATE: SIZE DATE Jan 27, 2014 www.linear.com TP6 GND KILL TP5 TP3 EN TP2 INT E TECHNOLOGY C4 0.47uF 10V R3 100k TITLE: SCHEMATIC JP3 3 2 D2 GRN 2V EN R2 100 INT/KILL 1 TIE APPROVALS 2 GND OUT Dilian Reyes REVISION HISTORY APPROVED DESCRIPTION D PRODUCTION(Replaced S1, D1 & D2) 2.6V D5 11V (Opt) C U2 LT3014BES5 D4 11V (Opt) ECO REV 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. C1 0.033uF 8 6 5 OFFT KILL EN 3 OPEN C INT 2 PB VIN 3 2 1 U1 LTC2950CTS8-2 ONT/KILLT 1 0.033uF 2 NOTE 1. EN, the inverse of EN, is available in the LTC2950-1/LTC2951-1. KEYSTONE #232 RED B GND 4 ONT/KILLT 3 OFFT 4 7 A 1 2 3 4 DEMO MANUAL DC826C-A/DC826C-B SCHEMATIC DIAGRAM dc826cf 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 1 2 3 4 BLK GND TP7 TP4 S1 ON/OFF 5.1k RF 1k VIN 2.7V-26.4V PB RRPP VIN TP1 CF 0.1uF 50V CRPP 0.1uF 50V A B 1 JP1 OPEN VIN CUSTOMER NOTICE JP2 C2 0.033uF 0.033uF D3 11V (Opt) SEE NOTE #1 3 1 NC IN C:\PADS PROJECTS\826C-B\SCH\826C-B_REV1.DSN THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. C D1 RED 2V INT R1 100 ADJ 4 SCALE = NONE D APP ENG. Dilian Reyes PCB DES. APPROVALS 2 GND OUT R5 100k 1% R4 113k 1% 2.6V IC NO. E SHEET 1 OF 1 1 REV. MODIFY DATE: SIZE DATE Jan 27, 2014 www.linear.com TP6 GND KILL TP5 TP3 EN TP2 INT E TECHNOLOGY C4 0.47uF 10V R3 100k TITLE: SCHEMATIC JP3 3 2 D2 GRN 2V EN R2 100 INT/KILL 1 TIE UNTIE 5 Dilian Reyes REVISION HISTORY APPROVED DESCRIPTION D PRODUCTION(Replaced S1, D1 & D2) 2.6V D5 11V (Opt) C U2 LT3014BES5 D4 11V (Opt) ECO REV 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. C1 0.033uF 8 6 5 OFFT KILL EN 3 OPEN C INT 2 PB VIN 3 2 1 U1 LTC2951CTS8-2 ONT/KILLT 1 0.033uF 2 NOTE 1. EN, the inverse of EN, is available in the LTC2950-1/LTC2951-1. KEYSTONE #232 RED B GND 4 ONT/KILLT 3 OFFT 7 A 1 2 3 4 DEMO MANUAL DC826C-A/DC826C-B SCHEMATIC DIAGRAM dc826cf 5 DEMO MANUAL DC826C-A/DC826C-B 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. Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation 6 dc826cf Linear Technology Corporation LT 0815 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2015