ZXCT1032EV1 USER GUIDE Figure 1 Evaluation board components' layout DESCRIPTION The ZXCT1032EV1 provides a very convenient means for evaluating the capabilities of the ZXCT1032 current monitor. The ZXCT1032 is a high-side current monitor that drives a PMOS or PNP transistor to provide in-rush current limit and over-current protection. The ZXCT1032 includes a high accuracy high-side current monitor, a start-up timer and a re-try inhibit timer. The ZXCT1032 takes the voltage developed across a current shunt resistor and compares this with an externally set trip point. It works in three modes: • Linear soft-start • Over-current detector • Over-current disconnect/fuse For details on these and other features of the ZXCT1032, refer to the datasheet which is available on the Zetex Semiconductors’ web site. The evaluation board is more complex than the typical application of the device. This is because it contains some features to aid with experimentation and visualisation of the operational status of the device. Some of these will be briefly explained with reference to Figure 1. Issue 1 – December, 2008 © Diodes Incorporated, 2008 www.zetex.com www.diodes.com ZXCT1032EV1 P1 2 1 R6 S+ S- MPT2 UDF Vsup SLR2 0R5 R1 P2 S- SL1 ZXMP3A17E6 Q101 OUT 0R05 6 8 R8 10k R7 S- R5 2.2k 3 ISET 5 Drive ZXCT1032 2 1 R9 10k R4 2.2k D1 LGR971-Z FOK R10 10K D2 LOR976-Z FTP Flag R11 47k C1 100pF CT R3 2.2k D5 D4 D3 LSR976 PWR Vsup Flag 4 CT 2 1 GND UDF P5 CT GND Vsup GND Drive IC1 VR1 10k OUT GND GND MPT3 Viset MPT4 3 2 1 TRP 4 3 2 1 1. UDF = User DeFined P3 SLR1 S+ Vsup GND Viset GND NOTES SL2 R2 ZHCS500 TRP ZHCS500 P4 4 3 2 1 MPT4 Q2 ZXMN2A01F Q3 ZXMN2A01F MPT2 GND Figure 2 Circuit diagram for evaluation board ZXCT1032EV1 Supply Range 9.5V to 20V Current sensing The sense resistor, RS, consists of two resistors (R1 and R2) which are configured in parallel such that either one or both resistors could be connected by completing the solder-bridge link next to each one. R2 (0.5R) is connected by default. A third resistor, R6, is in parallel with R1 and R2 consists of two pads with a hole in each pad. R6 provides means for connecting an external RS either alone or in parallel with R1 and R2. Trip current When the load current reaches or exceeds a certain value, transistor Q101 is switched off. The current at which this happens is given by, V − 0.15 ITRIP = ISET 10 ⋅ R SENSE With the default values supplied on the evaluation board, this becomes ITRIP = 2.1 − 0.15 = 390mA 10 ⋅ 0.5 The board is supplied without R7 which means that VISET defaults to the internal 2.1V reference. An external VISET can be imposed on terminal P2-2. A lower VISET will lower the trip current and vice versa. A VISET of less than 100mV will permanently turn the series transistor off. Issue 1 – December 2008 www.zetex.com www.diodes.com © Diodes Incorporated 2008 2 TRP GND TRP GND ZXCT1032EV1 On-board adjustment of VISET As an alternative to using the on-board voltage reference for VISET, a multi-turn potentiometer, VR1, is provided on the evaluation board. This can be connected to the VISET input by adding R7. R7 can be any value from 0 to 2.2k. It might however be best not to make R7 zero if external VISET will also be used so that the external source of VISET is not inadvertently shorted out when VR1 is set to 0Ω. When VR1 is supplying VISET, the range will be adjustable from a minimum value up to a maximum value that is largely dependent on the supply voltage. The minimum and maximum values can be determined from the following expressions. VISET (min) = VREF ⋅ R 7 2 .1 ⋅ R 7 = R 7 + RVREF R 7 + 50k where R7 is in kΩ and both VISET and VREF are in Volts. RVREF is the source resistance of the on-chip voltage reference. VISET (max) = where VT = VT ⋅ RVREF + VREF ⋅ RT RVREF + RT VSUP and RT = 5k + R 7 . 2 For R7 = 2.2kΩ, the above formulae simplify to VISET (min) = 2 .1 ⋅ 2 . 2 = 92.7mV (VR1 at minimum) 2.2 + 50 VISET (max) = 0.437 ⋅ VSUP + 0.264 V (VR1 at maximum) Flags and indicators The ZXCT1032 has an active low flag which goes low when the device has tripped. This flag is used to provide a number of indications regarding the status of the evaluation board. LEDs There are two LEDs labelled FOK (Flag OK - green) and FTP(Flag TriPped - yellow). These light to indicate their respective functions. There is a third LED labelled PWR (PoWeR – red) which will be on as long as there is power on at the output, i.e. Q101 is on. Flags The device flag is buffered by a two stage transistor (Q2,3) to provide an active high ( TRP ) and active low ( TRP ) tripped flag which are available on terminals P4-2 and P4-4 respectively. Terminals P4-1 and P4-3 are ground pins. Both the TRP and TRP pins can sink currents up to 500mA from a voltage not greater than (VSUP + 5V) or 30V whichever is the lower. Issue 1 – December 2008 www.zetex.com www.diodes.com © Diodes Incorporated 2008 3 ZXCT1032EV1 Interfaces The interfaces are as shown in Figure 1. P1 – VSENSE - Provides a convenient point to monitor VSENSE. Do not use this terminal for shunt resistors especially when handling high currents. Use R6 instead. P1 1 2 SS+ P2 1 2 3 4 Ground VISET Ground Supply voltage 9.5V – 20V P3 1 2 3 Ground Ground Output To load P2 – Input 0V - VSUPPLY P3 – Output P4 – Flags P4 1 2 3 4 Ground Tripped Ground Active high Tripped Active Low P5 – Timing capacitor CT. There is an on-board 0.1µF capacitor. Any addition across P5 will appear in parallel with this 0.1µF capacitor. P5 1 2 Ground CT No limit ORDERING INFORMATION ORDER NUMBER ZXCT1032EV1 Please note evaluation boards are subject to availability and qualified leads. Issue 1 – December 2008 www.zetex.com www.diodes.com © Diodes Incorporated 2008 4 ZXCT1032EV1 ZXCT1032EV1 Summary Sense resistor The board has been designed with two selectable values of sense resistor. The value of the sense resistor can be chosen by using the solder links SL1 and SL2. The board is also tracked for a user-defined through-hole resistor (R6). The 50mΩ resistor (R1) is selected by shorting SL1 and opening SL2. The 500mΩ resistor (R2) is selected by shorting SL2 and opening SL1. If both links are shorted the effective resistance is 45.45 mΩ. If both links are open, the optional leaded resistor R6 can be exclusively used as the sense resistor. The maximum power dissipation rating of the resistor must be appropriate to the load current level. For further information on choosing a value of sense resistor please refer to the ZXCT1032 datasheet. Trip current sensitivity and its adjustment The current at which the ZXCT1032EV1 trips (DRIVE goes high and FLAG goes low) for a given RS is changed by setting VISET. This trip current is given by, ITRIP = VISET − 0.15 10 ⋅ RS Configuration table for ZXCT1032EV1 RS (mΩ Ω) Trip Current SOLDER LINK CONFIGURATION 50 500 3.9 0.39 Short SL2 Short SL1 45.45 4.3 Short SL1 & SL2 NOTES Configuration for different trip currents. The board can be configured for different trip currents by changing the SMD resistors or fitting a suitable wire ended resistor and opening both solder links. It is important to ensure an appropriate value of RS is selected to obtain the desired accuracy for a given output current. Choosing a larger value for RS gives a higher output voltage for a given current resulting in better resolution but at the expense of increased voltage drop and higher dissipation in RS. The ZXCT1032 is optimized for values of VSENSE around 200mV. Accuracy The accuracy of the trip current will be influenced by the tolerance of the external sense resistors used. The ZXCT1032EV1 utilizes 1% sense resistors. Issue 1 – December 2008 www.zetex.com www.diodes.com © Diodes Incorporated 2008 5 ZXCT1032EV1 COMPONENTS LIST Ref Qty Value Pkg Part Number Manufacturer C1 D1 D2 D3 D4,5 IC1 1 1 1 1 2 1 0805 0805 0805 0805 SOT-23 SO8 LGR971-Z LYR971-Z LSR976 ZHCS500 ZXCT1032N8 Osram Osram Osram Zetex Zetex FEC 122-6373 FEC 122-6420 FEC 122-6392 P1,5 P3 P2,4 Q101 Q2,3 R1 R2 R3,4,5 R8,9,10 R11 RV1 2 1 2 1 2 1 1 3 3 1 1 25 0.1µF/25v LED Grn LED Yel LED Red Schottky Current Monitor 2-W STB 3-W STB 4-W STB FET FET 50mΩ 500mΩ 2.2k 10k 47k 10k MPT2 MPT3 MPT4 SOT-23-6 SOT-23 2512 2512 0805 0805 0805 Trim-pot 1725656 1725669 1725672 ZXMP3A17E6 ZXMN3B01F LR2512-R050FW LR2512-R500FW Standard 0805 1% Standard 0805 1% Standard 0805 1% T93YB 10k 10% TU Phoenix Phoenix Phoenix Zetex Zetex Welwyn Welwyn FEC 304-1359 FEC 304-1360 FEC 304-1414 SMD Sense Resistor 1% SMD Sense Resistor 1% Vishay FEC 114-1419 Total Notes SET-UP AND TEST The board is preset to trip at a load current of 390mA (SL2 is shorted to connect in R2, 500mΩ, sense resistor and internal VREF is used). Required Equipment 1. 2. 1 x 30R 15W resistor (load – it may be necessary to mount resistor on heat sink). 1 x adjustable bench PSU. (A second PSU can optionally be used to vary VISET to change the trip current - see Error! Reference source not found. – or the on-board variable resistor may be used instead.) 2 x DVM’s (one for voltage measurement and one for current measurement) 1.5/1.8mm flat jeweller’s screw driver (for terminal blocks). 3. 4. 420mA load test (Refer to Error! Reference source not found. for test diagram.) 1. 2. 3. 4. 5. Ensure SL2 is shorted. Set PSU1 to 0V and limit its current to 500mA. Connect PSU1 to VSUP. Connect the resistor in series with the ammeter set to a suitable range for measuring up to 500 mA DC. Switch on PSU1 and adjust until the ammeter reads 350 mA ±1 mA. LED’s PWR and FOK should be lit. 6. 7. 8. On terminal P4, measure pin TRP with a DVM. It should be high. On terminal P4, measure pin TRP with a DVM. It should be low. Increase PSU1 until ammeter current drops to less than 40mA. Make sure that this happens around 390mA ±30mA (the yellow LED will light whilst the red and green LED’s will glow at a reduced brightness - some flickering may be observed). (1) 9. On terminal P4, measure pin TRP with a DVM. It should be low. Low means less than 0.15VSUP. (Error! Bookmark not defined.) 10. On terminal P4, measure pin TRP with a DVM. It should be high. High means greater than 0.85VSUP. End of Test 1 The voltage on pins TRP and TRP are square waves with complementary low and high duty cycles respectively. The duty cycle is governed by capacitor CT. Therefore, the coefficient of VSUP given for these tests will change if a different value of CT is used. The same thing applies to the 40mA limit in Test 8. Issue 1 – December 2008 www.zetex.com www.diodes.com © Diodes Incorporated 2008 6 ZXCT1032EV1 ZXCT1032EV1 + PSU2 P1 S+ S- P2 GND VISET GND VSUP PSU1 + 30R 15W P3 A OUT GND GND GND CT TRP GND TRP GND P5 P4 DVM Figure 3 Test diagram for ZXCT1032EV1 EVALUATION BOARD Issue 1 – December 2008 www.zetex.com www.diodes.com © Diodes Incorporated 2008 7 ZXCT1032EV1 Definitions Product change Diodes Incorporated reserves the right to alter, without notice, specifications, design, price or conditions of supply of any product or service. Customers are solely responsible for obtaining the latest relevant information before placing orders. Applications disclaimer The circuits in this design/application note are offered as design ideas. It is the responsibility of the user to ensure that the circuit is fit for the user’s application and meets with the user’s requirements. No representation or warranty is given and no liability whatsoever is assumed by Diodes Inc. with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Diodes Inc. does not assume any legal responsibility or will not be held legally liable (whether in contract, tort (including negligence), breach of statutory duty, restriction or otherwise) for any damages, loss of profit, business, contract, opportunity or consequential loss in the use of these circuit applications, under any circumstances. Life support Diodes Zetex products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein: A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Reproduction The product specifications contained in this publication are issued to provide outline information only which (unless agreed by the company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. Terms and Conditions All products are sold subjects to Diodes Inc. terms and conditions of sale, and this disclaimer (save in the event of a conflict between the two when the terms of the contract shall prevail) according to region, supplied at the time of order acknowledgement. For the latest information on technology, delivery terms and conditions and prices, please contact your nearest Diodes sales office. Quality of product Diodes Zetex Semiconductors Limited is an ISO 9001 and TS16949 certified semiconductor manufacturer. To ensure quality of service and products we strongly advise the purchase of parts directly from Zetex Semiconductors or one of our regionally authorized distributors. For a complete listing of authorized distributors please visit: www.zetex.com or www.diodes.com. Diodes Zetex Semiconductors does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels. ESD (Electrostatic discharge) Semiconductor devices are susceptible to damage by ESD. Suitable precautions should be taken when handling and transporting devices. The possible damage to devices depends on the circumstances of the handling and transporting, and the nature of the device. The extent of damage can vary from immediate functional or parametric malfunction to degradation of function or performance in use over time. Devices suspected of being affected should be replaced. Green compliance Diodes Zetex Semiconductors is committed to environmental excellence in all aspects of its operations which includes meeting or exceeding regulatory requirements with respect to the use of hazardous substances. Numerous successful programs have been implemented to reduce the use of hazardous substances and/or emissions. All Diodes Zetex components are compliant with the RoHS directive, and through this it is supporting its customers in their compliance with WEEE and ELV directives. Product status key: “Preview” “Active” “Last time buy (LTB)” “Not recommended for new designs” “Obsolete” Datasheet status key: “Draft version” “Provisional version” “Issue” Future device intended for production at some point. Samples may be available Product status recommended for new designs Device will be discontinued and last time buy period and delivery is in effect Device is still in production to support existing designs and production Production has been discontinued This term denotes a very early datasheet version and contains highly provisional information, which may change in any manner without notice. This term denotes a pre-release datasheet. It provides a clear indication of anticipated performance. However, changes to the test conditions and specifications may occur, at any time and without notice. This term denotes an issued datasheet containing finalized specifications. However, changes to specifications may occur, at any time and without notice. Sales offices The Americas Europe Taiwan Shanghai Shenzhen Korea 3050 E. Hillcrest Drive Westlake Village, CA 91362-3154 Kustermannpark Balanstraße 59, D-81541 München 7F, No. 50, Min Chuan Road Hsin-Tien Rm. 606, No.1158 Changning Road Shanghai, China Room A1103-04, ANLIAN Plaza, #4018 Jintian Road 6 Floor, Changhwa B/D, 1005-5 Yeongtong-dong, Yeongtong-gu, Suwon-si, Tel: (+1) 805 446 4800 Fax: (+1) 805 446 4850 Germany Tel: (+49) 894 549 490 Fax: (+49) 894 549 4949 Taipei, Taiwan Tel: (+886) 289 146 000 Fax: (+886) 289 146 639 Tel: (+86) 215 241 4882 Fax (+86) 215 241 4891 Futian CBD, Shenzhen, China Tel: (+86) 755 882 849 88 Fax: (+86) 755 882 849 99 Gyeonggi-do, Korea 443-813 Tel: (+82) 312 731 884 Fax: (+82) 312 731 885 Issue 1 – December 2008 www.zetex.com www.diodes.com © Diodes Incorporated 2008 8