User`s Manual - Cap-XX
Contents
1. an Evaluation Board because different applications will require different load voltages The hysteresis also needs to be adjustable because a step in load current will cause a step voltage on the supercapacitor because of the supercapacitor s Equivalent Series Resistance ESR Since this step voltage part of the ripple is a normal occurrence it would not be desirable for this to indicate that the supercapacitor is undercharged Power Good LED On LED Off a lt Vy gt i Figure 1 Power Good Hysteresis cap XX Pty Ltd 2003 4 WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 As in Figure 1 the high threshold Vrh is the voltage at which the supercapacitor s unloaded voltage becomes acceptable The hysteresis Vw is the voltage that when subtracted from the high threshold gives the low threshold It indicates that the supercapacitor is undercharged is set by the factory at 3 2V and Vy is set at 0 3V therefore V1 is 2 9V PGOOD has a header labeled on the Evaluation Board as H PGOOD It is an active high output signal that can be used to signal an external circuit that the supercapacitor is fully charged A green LED is also included to indicate this condition It is labeled on the Evaluation Board as Power Good 6 0 Adjusting the Circuit Equipment needed Adjustable power supply multi meter and various power resistors Warning Be careful not to exceed the su2. 3 Adjusting the Current Limit with Current Limit Ro 7 6 4 Replacing the Potentiometers with Fixed Resistors 7 6 5 Limits of Adjustment 7 70 Connecting the Evaluation Board to a Test Platform 8 7 1 Application Hints 9 8 0 Disconnecting Circuits for Reduced Load 9 Appendix 10 Schematic 10 PCB Top Overlay 11 PCB Top Layer 12 PCB Bottom Layer 13 cap XX Pty Ltd 2003 2 WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 1 0 Introduction This User s Manual is for the cap XX Supercapacitor Evaluation Board Part No APPEB1002 This board was designed for the evaluation of a supercapacitor in a typical application The application of supercapacitors is limited only by the user s imagination Typical examples are PDA Compact Flash PC Card Smartphone GPRS and other handheld equipment The Evaluation Board is basically a supercapacitor with a current limit circuit that can be simply connected to a Test Platform An excellent source for information on Supercapacitors and free downloads are available on the cap XX website at www cap xx com In the following description of operation it may be helpful to refer to the Evaluation Board Schematic in the Appendix 2 0 Input Voltage The supercapacitors for the Evaluation Board are rated at 4 5V and therefore it is not recommended that the input voltage Vcc be greater than 4 5V If Vcc is 5V then the Equivalent Series Resistance rise rate of the supercapacitor is increas
3. OOD H_PGOOD X u_ENABLE C LX JH CAPXX cap XX Pty Ltd 2003 11 WWW Ccap xx com APPEB1002 User s Manual Rev 1 0 January 2003 PCB Top Layer cap XX Pty Ltd 2003 APPEB1002 User s Manual Rev 1 0 January 2003 PCB Bottom Layer r d s x x x x cap XX Pty Ltd 2003 13
4. WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 Cap XX Supercapacitor Evaluation Board Part No APPEB1002 User s Manual Revision 1 0 January 2003 Supercapacitor Evaluation Board Part No APPEB1002 PGOOD Feedback R WWwW cap xx com CR 200015 vots PGOOD Reference g 20 L1 Volts 1 2 ower Supercapacitor ale SB imm Geod m P m 2 dU Q Applications 9 e PDA AI 28 C 2 RED amp YLW yb 4 I x e Compact Flash 5 CI GREEN e PC Card 2c 77 P6OOD o R4 e phone 8 Ue M CC 9 ENABLE e Handheld Equipment 1 e Load Leveling 4 CON CAPXX 8 ly VCC_OUT GND_OUT Evaluation Board Features e Supercapacitor two form factors e Adjustable current limit circuit with Supercapacitor charge enable e 3 3V and 5V input LEDs e Supercapacitor voltage comparator with adjustable threshold adjustable hysteresis and Power Good LED Sub circuits can be disconnected to reduce the load e Test points jumpers and I O connectors cap XX Pty Ltd 2003 1 WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 Contents 1 0 Introduction 3 2 0 Input Voltage 3 2 1 Charge Time 3 3 0 Current Limit 4 4 0 Enable 4 50 Power Good 4 6 0 Adjusting the Circuit 5 6 1 Adjusting Hysterisis Width with PGOOD Feedback R23 6 6 2 Adjusting the High Threshold with PGOOD Reference R 6 6
5. e supply of the Pulsed Load respectively For the least voltage droop it is important to minimise the resistance between the supercapacitor and its load Therefore the wires from to the Pulsed Load should be as short and as thick as practical z TEN gy x Test Platform PNE gt m 88 E B 5 lm ct Mu Pulsed loads sti GO EG A 555 eg GPRS Module 38 RI2 Ril RIB en T a BB 3 a V ae S mai H_VCC_IN 05 07 8 3zS ra RB 132 rd M1 RIAL CIE gR22 8 02 1 1B P Also includ isis eqni so include 8 al E pict power diode if 3 0V 5 OV o g3 3 151121 VCC gt 4 5V Figure 2 Typical connection of Evaluation Board to a Test Platform cap XX Pty Ltd 2003 8 WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 7 1 Application Hints Figure 2 shows the typical way for connecting the Evaluation Board to the Test Platform However Vcc on the Test Platform is generally used in one of two modes Mode 1 is when Vcc directly supplies all the circuitry on the Test Platform Other Circuitry except for the Pulsed Loads V which is supplied indirectly via the supercapacitor In this mode Vcc is available to the O
6. e to say 3 3VDC Ensure that the power supply can supply the desired current Connect its negative lead to any pin on the header labeled H GND IN Connect the positive lead to any pin on the header labeled H VCC IN The LED labeled 3 3 Volts should now be ON and the LED labeled Power Good should also be ON If Power Good is not ON then turn PGOOD Reference Ris anticlockwise slowly until the Power Good LED is ON c Connect a voltmeter across the supercapacitor which is also across and CAPXX V Slowly reduce the power supply voltage and note Vp When the Power Good LED turns OFF Slowly increase the power supply voltage and note V when the Power Good LED turns ON The difference between the two readings is the hysteresis voltage width Vw d Adjust PGOOD Feedback R23 anti clockwise increases Vy and repeat c above until precisely the desired hysteresis width is achieved 6 2 Adjusting the High Threshold with PGOOD Reference R15 a Turn PGOOD Reference R15 fully clockwise and then reduce the power supply voltage until the Power Good LED is OFF b Adjust the power supply voltage so V equals the desired Vrh Turn PGOOD Reference R15 slowly anti clockwise until the Power Good LED turns ON c Check that the Power Good LED turns ON and OFF at the desired levels This can be done by varying the power supply voltage in both directions so that V is less than Vr and t
7. ed and the lifetime will be reduced A red LED is included to indicate that Vcc is too high and it starts to glow when Vcc is approximately 4 2V The red LED is labeled on the Evaluation Board as 5 Volts If Vcc is 5V then the voltage can be dropped to 4 5V by including an external series diode in the voltage supply line of the Evaluation Board A typical voltage for these supercapacitors is 4 2V and less and therefore ideal for Li ion battery applications such as PDAs and smartphones or 3 3V PC Cards and Compact Flash 5V versions are easily accommodated by including the series diode A yellow LED is included to indicate when Vcc is 3 3V or greater It is labeled on the Evaluation Board as 3 3 Volts If Vcc is disconnected and there is still charge on the supercapacitor then current will flow through the body diode of M1 and through the yellow LED also through the red LED if the supercapacitor is greater than 4 2V In this case the intensity of the yellow LED gives an indication of the voltage remaining on the supercapacitor 2 1 Charge Time A fully discharged supercapacitor will be charged to Vcc after a certain time t This time will depend on the current limit IL Vcc and the capacitance C The equation is _ n t c 1 cap XX Pty Ltd 2003 3 WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 3 0 Current Limit Circuits that employ large capacitors generally need a current limitin
8. ematic 8 pins for VCC allow for connecting to the host as well as some test points R1 MW MI 22m SUD45P03 10 TPS RA H_CAPXK VCC IN c2 40k 10k 1 5 ci R5 1 2 H oxi 1 2 Di R2 AT T 39k IA 31M Ta FDva02P 5 NL LS LM4041DIM3 1 2 VCC IN M2 31g 2 81852 JUMPER1 22k R6 RI 8 2 i Ro RB JUMPERA 22 alb AN S RO Am UIA FDV301N 4 1 100 VCC IN Ihe intensity of the Yellow LED gives an indication J Enable can have its jumper removed and can be driven bf the voltage on the supercap when VCC IN is disconnected by an external open collector if desired 02 J ENABLE JUNPERI Rit ANY 470 1 Yellow LED J_RED amp YLW 1 2 L R12 De JUMPER 3 1 9 BZXBAC3V3 2 CAPXX Red_LED CON_CAPXX is to connect low resistance leads from VCC to the test circuit so there is a low resistance path from the supercap to the load If VCC_IN is 5V then both the Red and Yellow LEDs will be on CONS If VCC IN is 3 3V then only the Yellow LED will be on These LEDs will also be powered by the supercapacitor through the body diode of the current limiting Mosfet M1 when VCC IN is disconne d The LEDs can be disconnected so as to n
9. g circuit to alleviate the current in rush problem The Evaluation Board has an adjustable current limit circuit The current limit can be adjusted from to 4 5A by using the potentiometer R2 It is labeled on the Evaluation Board as Current Limit Turning the potentiometer clockwise will increase the current limit The MOSFET M1 and Sense Resistor R1 can withstand up to 4 5A whilst the supercapacitor is being charged They cannot however withstand the 4 5A indefinitely Also there is no short circuit protection The MOSFET M1 has a maximum average power dissipation of 2 5W Therefore any continuous load resistance R has a minimum value as given by equation 2 Noch 2 5 Ri m 2 4 0 Enable The current limit circuit has an enable feature Enab e is an active low signal and the two pin jumper is labeled the Evaluation Board as J ENABLE It is an input signal to the Evaluation Board and it can be jumpered to ground to be permanently enabled or it can be externally driven by an open collector or drain When J ENABLE is externally driven it allows the supercapacitor to be charged only when the Test Platform is ready 5 0 Power Good The Power Good circuit PGOOD is included to indicate when the supercapacitor is charged to the appropriate level The voltage on the supercapacitor is compared to a reference using a comparator with adjustable thresholds and hysteresis The thresholds need to be adjustable on
10. hen greater than Vry d Remove R cap XX Pty Ltd 2003 6 WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 6 3 Adjusting the Current Limit with Current Limit Ro Warning the maximum average power rating for M1 is 2 5W see section 3 0 a Connect a load resistor to CAPXX R that draws just over the desired current limit for the application Note the power rating of the resistor is according to equation 3 and R has to be a minimum value according to equation 2 For example if the supply voltage is 3 3V and the desired current limit is 1A then an R lt 3 3 Q would draw more than 1A According to equation 2 RL gt 800m2 Choose say 2 70 next standard value 3 3 Q and equation 3 says the power rating must be greater than 4W b With an ammeter in series with the power supply adjust Current Limit R2 until the current is limited to the desired value clockwise increases the current c Remove the load 6 4 Replacing the Potentiometers with Fixed Resistors The potentiometers on the Evaluation Board are included to provide flexibility in evaluating many different applications In a final design for production the resistance of the potentiometers would have been decided and therefore they can be replaced with fixed resistors This section includes the equations that can be used to theoretically determine the value of these resistors The value of these resistors can also be found prac
11. ot load the circuit VCC IN R14 4k7 T Power Good Circuit 1 TS c If H PGOOD is high then the supercap rail is good 7 Le Ris JUMPERA H GND IN R16 VCC IN R17 3k9 TS1852 22k 4 H_PGOOD R18 R19 470 1 7 Law 1 2 5 8 pins for H GND IN allow for connecting to the Green LED host as well as some test points vec IN 07 JUMPER1 NS US R20 ZRC250 22k R21 BCX20 2 500k R23 R22 70 J_GREEN R23 22k 2 5 Vw R22 JUMPER1 PGOOD Vr Vh Vw 2 5 2 1 2 width of hysteresis 1 h threshold 4 ref ce JUMPER1 Linking all POWER GOOD grounds and then jumpering to common ground allows the POWER GOOD circuit to be disconnected cap XX Pty Ltd 2003 10 WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 PCB Top Overlay Supercapacitor Evaluation Board Part No APPEB1002 PGOOD Feedback R www cap xx com M o Us u PGOOD Reference 2 v B ros LI L J LD mI Current Limit ol ei LU Ki R21 R R R Rz 21 LI D R9 N CON CAPXX VCC_OUT GND_OUT 2L 5 Volts 2010133 Volts 2 Power s L Good SQQ PE X Ju RED amp YLW LX JJ GREEN LX JJ PG
12. percapacitor rated voltage 4 5V or the maximum average power rating for M1 2 5W Sections 6 1 6 2 and 6 3 explain how to adjust the circuit practically and section 6 4 gives the theoretical equations a Connect a load power resistor RL of around 108 from VCC OUT to GND_OUT on CON CAPXX This ensures that the supercapacitor voltage will change in reasonable time when the power supply voltage is changed Note the power rating of has to be a minimum value according to equation 3 VCC OUT P R R 3 b Ensure jumpers J_RED amp YLW J_GREEN J_PGOOD and J_ENABLE are fitted c Turn the Current Limit R2 fully clockwise maximum current d Turn the PGOOD Reference to around mid position about 11 turns from either limit cap XX Pty Ltd 2003 5 WWW cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 6 1 Adjusting Hysteresis Width with PGOOD Feedback R5 NOTE V is adjusted before Vr because the Vr adjustment is affected by Vw Therefore if adjustments are made in this section then section 6 2 should be checked a Decide the high threshold voltage Vrh the low threshold voltage Vr and the hysteresis voltage width Vw Vw Vr Vr has to be greater than the minimum voltage required by the Pulsed Load Vw has to be greater than the expected voltage droop due to the ESR and capacitor discharge etc b Set the power supply voltag
13. ther Circuitry as soon as the Test Platform is powered up whereas the supercapacitor supply to the Pulsed Loads is delayed by the charge up time according to equation 1 Mode 2 is when Vcc is taken from the Test Platform and it only supplies the Evaluation Board The supercapacitor then supplies the Pulsed Loads as well as the Other Circuitry on the Test Platform In this mode all supplies are delayed according to equation 1 Care must be taken in which ever mode is chosen so that the charge up time of the supercapacitor does not affect the operation of any reset or power rail monitoring circuitry etc As described in section 4 0 and 5 0 the J ENABLE and H_PGOOD signals may need to be interfaced with the Test Platform for proper control 8 0 Disconnecting Circuits for Reduced Load The minimum voltage on some loads may be critical Any current that the Evaluation Board uses contributes to the droop on the input voltage If the droop becomes excessive then some of the functions on the Evaluation Board can be disconnected to save current and therefore increase the input voltage The red and yellow LEDS can be disconnected by removing the jumper J_RED amp YLW The green LED can be disconnected by removing the jumper J_GREEN The entire PGOOD circuit can be disconnected by removing the jumper J_PGOOD cap XX Pty Ltd 2003 9 WWW cap xx com APPEBI002 User s Manual Rev 1 0 January 2003 Appendix Sch
14. tically by measuring the resistance of the potentiometers out of circuit once the circuit has been successfully adjusted as above R22 R23 4 Vw R15 R16 ___4 7 5 5 Vy VH Bis 22K 6 56 1 L 6 5 Limits of Adjustment From the schematic in the Appendix it can be seen that R22 100kQ R23 500kQ potentiometer R15 5kQ potentiometer R16 3k9Q R2 2kQ potentiometer cap XX Pty Ltd 2003 I www cap xx com APPEB1002 User s Manual Rev 1 0 January 2003 From equation 4 0 1V Vy lt 0 5V From equation 5 2 3V lt Va lt 3 3V Vw 0 1V 24 Voy lt 3 5V Vw 0 3V 2 5V lt Voy lt 3 6V Vw 0 5V From equation 6 lt I lt 47 If these limits do not suit the application then resistors be replaced on the Evaluation Board according to equations 4 5 and 6 7 0 Connecting the Evaluation Board to a Test Platform There are two eight pin headers on the Evaluation Board labeled H_GND_IN and H_VCC_IN These are to be connected to the ground and Vcc of the user s Test Platform respectively as in Figure 2 As stated earlier if Vcc is 5V then the voltage should be dropped to lt 4 5V by including an external series diode before the connection to H_VCC_IN The supercapacitor terminals are joined to the connector labeled CON_CAPXX The terminals of CON CAPXX are labeled GND OUT and VCC OUT These are to be connected as close as possible to the ground and positiv
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