DEMO MANUAL DC1735A LTC3226EUD 2-Cell Supercap Charger With Backup PowerPath Controller DESCRIPTION Demonstration circuit DC1735A is a 2-cell supercap charger with a backup PowerPathTM controller, featuring the LTC(R)3226. It includes a charge-pump supercapacitor charger with programmable output voltage, a low dropout regulator and a power-fail comparator for switching between normal and backup modes. The constant-input current supercapacitor charger is designed to charge two supercapacitors in series to a resistor programmable output voltage from a 2.5V to 5.3V input supply. The charger input current limit is programmable by an external resistor up to 315mA. The internal backup LDO is powered from the supercapacitors and provides up to 2A peak output current with an adjustable output voltage. When the input supply falls below the resistor programma-ble power-fail threshold, the LTC3226 automatically enters a backup state in which the supercapacitors power the output through the LDO. The LTC3226 is available in a 16-lead, 3mm x 3mm QFN surface mount package with an exposed pad. 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 and PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. PERFORMANCE SUMMARY Specifications are at TA = 25C SYMBOL PARAMETER CONDITIONS VIN Input Voltage Range IVIN(ILIM) Input Current Limit RPROG = 33.3k VSTACK Supercap Stack Output Voltage RCP1 = 3.83M, RCP2 = 1.21M VMID Supercap Midpoint Voltage MIN TYP 2.5 MAX 5.5 315 UNITS V mA 5.3 5.5 V 2.65 2.75 V OPERATING PRINCIPLE The LTC3226 is a 2-cell series supercapacitor charger designed to back up a Li-ion battery or any system rail in the range of 2.5V to 5.3V. Its four principle circuit components are: 1. Dual (1x / 2x) charge pump with an integrated balancer and a voltage clamp 2. LDO to supply the load current from the charge stored on the supercapacitors 3. Ideal diode controller to control the gate of the external MOSFET between VIN and VOUT 4. PFI comparator to decide whether to activate the charge pump to charge the supercapacitor stack or to activate the LDO to supply the load when VIN falls below an externally programmed value. The LTC3226 has two modes of operation: normal and backup. If VIN is above an externally programmable PFI threshold voltage, the part is in normal mode and power flows from VIN to VOUT through the external MOSFET while the internal charge pump chargers the supercapacitor stack (see Figure 1). If VIN is below the PFI threshold, the part is in backup mode (see Figure 2). In this mode, the internal charge pump is turned off and the LDO is turned on to supply the load current from the stored charge on the supercapacitor stack. The device includes three open-drain, output status signals: CAPGOOD, PFO and RST. The CAPGOOD pin is an open-drain N-channel MOSFET transistor controlled by a comparator that monitors the voltage on the supercapacidc1735Af 1 DEMO MANUAL DC1735A OPERATING PRINCIPLE comparator which monitors VOUT under all operating modes via the RST_FB pin and reports the status via an open-drain NMPS transistor on the RST pin. At any time, if VOUT falls below 7.5% from its programmed value, it pulls the RST pin low almost instantaneously. However, on the rising edge, the comparator waits 290ms after VOUT crosses the threshold voltage before making the RST high impedance. 6 6 5 5 4 CPO 3 VMID 2 1 0 -1 VOUT 3 VIN 2 BACKUP BACKUP MODE MODE (LDO IN (LDO IN REGULATION) DROPOUT) 1 1x MODE CSC = 1.2F COUT = 47F ILOAD = 2A CPO 4 VIN VOLTAGE (V) VOLTAGE (V) 1V/DIV tor stack. This pin is pulled to ground until the CPO pin voltage rises within 7.5% of the programmed value. Once the CPO pin is above this threshold, the CAPGOOD pin goes high impedance. The output of the PFI comparator also drives the gate of an open-drain N-channel MOSFET to report the status via the PFO pin. In normal mode the PFO pin is high impedance, but in backup mode the pin is pulled down to ground. The LTC3226 contains a RESET 2x MODE RPROG = 33.2k CSC = 1.2F TIME (5 SECONDS/DIV) dc1735A F01 Figure 1. Charge Profile with Equal Value Supercapacitors 0 -1 PFO (2V/DIV) 0 0.4 0.8 1.2 TIME (SECONDS) 1.6 2.0 dc1735A F02 Figure 2. Normal-to-Backup Mode Switchover QUICK START PROCEDURE Refer to Figure 3 for the proper measurement equipment setup and jumper settings, and follow the procedure below. NOTE. When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the VIN or VOUT and GND terminals. See Figure 4 for the proper scope probe technique. 1. Initial jumper, power supply and load settings: JP1 = EN Power Supply = OFF JP2 = 110mA Load = Off JP3 = 110mA Pulse Generator = OFF 2. Connect the power supply to the VIN terminals, turn the power supply on, and increase the voltage to 2V while monitoring the input current. If the input current is less than 5mA, increase the voltage until the point at which PFO goes high. Verify that VIN is between 3.53V and 3.65V, the input current is approximately 320mA, the output voltage is approximately equal to the input voltage and the voltage on the CPO pin is rising. 3. Monitor the voltage on CPO and CAPGOOD. Verify that CAPGOOD goes high when CPO is at 4.6V and that CPO charges between 4.83V and 5.23V. Verify that VMID is one-half of CPO. Verify that RST is high. dc1735Af 2 DEMO MANUAL DC1735A QUICK START PROCEDURE 4. Turn on the load and increase the current to 2A. Verify that VOUT is within 50mV of VIN. 5. Decrease the power supply to 3V and quickly observe that VOUT is between 3.12V and 3.47V, PFI is low, RST is high and the voltage on CPO is falling. Increase VIN to 3.6V and verify that the voltage on CPO starts to rise again. Let the voltage on CPO rise beyond where CAPGOOD goes high. 6. Turn off the power supply and observe that VOUT remains between 3.12V and 3.47V for greater than 700ms, and that VOUT then falls, tracking CPO until VOUT reaches 2.4V. Verify that RST is low. 7. Disconnect the power supply from the VIN terminals, turn down the voltage to 0V and connect the power supply between the CPO and ground terminals. Slowly increase the voltage to 5V and verify that VOUT is between 3.12V and 3.47V. Increase the load on VOUT to 1A. Set up the pulse generator for an output voltage peak of 10V, a pulse with 1ms pulse width and a period of 20ms. Connect the pulse generator to the pulse generator terminals and observe the transient response on the VOUT terminals. Verify that the negative transition of VOUT is less than 75mV and that it recovers within 100s. Figure 3. Proper Measurement Equipment Setup for DC1735A GND VIN dc1735a F04 Figure 4. Measuring Input or Output Ripple dc1735Af 3 DEMO MANUAL DC1735A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 C2 Cap., Chip, X5R, 4.7F, 10%, 6.3V, 0603 Murata, GRM188R60J475KE19D 2 1 C3 Cap., Chip, X5R, 2.2F, 20%, 10V, 0603 Murata, GRM188R61A225KE34D 3 2 C4, C5 Cap., Chip, X7R, 0.1F, 10%, 16V, 0402 Murata, GRM155R71C104KA88D 4 1 C6 Supercap, 1.2F, 5.5V, 39mm x 17mm CAP-XX, HS230F 5 1 C7 Cap., Chip, X5R, 47F, 20%, 6.3V, 1206 Murata, GRM31CR60J476ME19L 7 1 R2 Res., Chip, 210k, 1/16W, 1%, 0402 Vishay, CRCW0402210KFKED 8 1 R3 Res., Chip, 121k, 1/16W, 1%, 0402 Vishay, CRCW0402121KFKED 9 1 R7 Res., Chip, 100k, 1/16W, 1%, 0402 Vishay, CRCW0402100KFKED 10 1 R8 Res., Chip, 3.83M, 1/16W, 1%, 0402 Vishay, CRCW04023M83FKED 11 1 R9 Res., Chip, 1.21M, 1/16W, 1%, 0402 Vishay, CRCW04021M21FKED 12 1 R10 Res., Chip, 255k, 1/16W, 1%, 0402 Vishay, CRCW0402255KFKED 13 1 R11 Res., Chip, 80.6k, 1/16W, 1%, 0402 Vishay, CRCW040280K6FKED 14 1 Q1 MOSFET, -20V, 33m, -5.5A, SUPERSOT-6 Fairchild, FDC604P 15 1 U1 2-Cell Supercapacitor Charger with Backup PowerPath Controller Linear Technology, LTC3226EUD Sanyo, 6VPE220M Additional Circuit Components 1 1 C1 Cap., SMD, OSCON, 220F, 20%, 6.3V, 6.3mm x 6mm 2 0 C8 (OPT) Cap., Chip, 0402 3 1 D1 SMD, Switching Diode, SOD323 Vishay, 1N4148WS-V-GS08 4 1 R1 Res., Chip, 1M, 1/16W, 1%, 0402 Vishay, CRCW04021M00FKED 5 1 R4 Res., Chip, 10k, 1/16W, 1%, 0402 Vishay, CRCW040210K0FKED 6 3 R5, R6, R16 Res., Chip, 100k, 1/16W, 1%, 0402 Vishay, CRCW0402100KFKED 7 3 R12 to R14 Res., Chip, 475k, 1/16W, 1%, 0402 Vishay, CRCW0402475KFKED 8 1 R15 Res., Chip, 1k, 1/16W, 1%, 0402 Vishay, CRCW04021K00FKED 9 2 R17, R18 Res., Chip, 6.65, 1/4W, 1%, 1206 Vishay, CRCW12066R65FKED 10 1 Q2 MOSFET, 30V, 65m, 3.5A, SOT-23 Vishay, Si2306BDS Hardware for Demo Board Only 1 4 E1, E2, E8, E9 Turret, 0.09 DIA Mill-Max, 2501-2 2 12 E3 to E7, E10 to E16 Turret, 0.061 DIA Mill-Max, 2308-2 3 3 JP1 to JP3 Header, 3 Pins, 2mm Samtec, TMM-103-02-L-S 4 3 JP1 to JP3 Shunt 2mm Samtec, 2SN-BK-G 5 4 Stand-Off, Nylon, 0.375" Tall (Snap On) Keystone, 8832 (Snap On) dc1735Af 4 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. E7 OFF ON R16 100K JP2 2. INSTALL SHUNTS AS SHOWN. 1. ALL RESISTORS ARE 0402, 1%, 1/16W ALL CAPACITORS ARE 0402, 10% JP3 VOUT Q2 Si2306BDS R18 6.65 1206 0.25W C3 2.2uF 10V X5R 0603 R6 100K R3 121K R2 210K R17 6.65 1206 0.25W 1 2 3 1 2 3 OFF ON 110mA R5 100K C8 OPT PFI 110mA C2 4.7uF 6.3V X5R 0603 NOTE: UNLESS OTHERWISE SPECIFIED GND 1K PULSE LOAD 5% DUTY CYCLE JP1 ENABLE 1 EN 2 3 OFF 10K R4 C1 220uf CAP-CV-6.3X6 6.3V R15 E5 E4 + E6 GND PROG ENABLE E3 GND E1 E2 3.3V-5.5V VIN VIN PROG PFI EN_CHG C- C+ PFI VIN 110mA 220mA 220mA OFF OFF ON ON OFF ON OFF ON 330mA I LIMIT JP3 JP2 GATE D1 1 11 2 7 6 4 10 14 16 1 5 C5 0.1uF 16V X7R C4 0.1uF 16V X7R 3 CUSTOMER NOTICE 4 BAL + THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. R8 3.83MEG NC JIM D. SCALE = NONE APP ENG. PCB DES. APPROVALS R12 475K R9 1.21MEG 1.2F HS230F 39mm x 17mm C6 R14 475K 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. 1N4148-SMD 2 CAPGOOD PFO RST RST_FB LDO_FB CPO_FB VMID CPO VOUT 3 Figure 5. Demo Circuit Schematic 1.0Meg R1 17 GND INPUT CURRENT LIMIT PROGRAMMING R7 100K 9 8 12 15 3 13 U1 LTC3226EUD 6 5 2 1 2 1 Q1 FDC604P DATE: N/A SIZE 05-16-11 IC NO. PFO RST E16 GND E15 CAPGOOD E14 E13 E12 GND E11 VMID LTC3226EUD DEMO CIRCUIT 1735A TECHNOLOGY GND E10 CPO E9 VOUT 3.3V - 5.5V 2.0A MAX DATE 05-16-11 SHEET 1 OF 1 2 REV. 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only C7 47uF 6.3V X5R 1206 20% E8 JIM D. APPROVED 2-CELL SUPERCAPACITOR CHARGER WITH BACKUP POWER PATH CONTROLLER TITLE: SCHEMATIC R11 80.6K R10 255K PRODUCTION VOUT DESCRIPTION 2 REVISION HISTORY REV R13 475K VOUT ECO DEMO MANUAL DC1735A SCHEMATIC DIAGRAM dc1735Af 5 DEMO MANUAL DC1735A 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 (c) 2004, Linear Technology Corporation dc1735Af 6 Linear Technology Corporation LT 0711 * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com (c) LINEAR TECHNOLOGY CORPORATION 2011