ZETEX ZXCT1009 Manual
Contents
1. DIMENSIONS SM8 Millimeters Inches Pin No 1 Zetex Semiconductors plc 2005 Europe Americas Asia Pacific Corporate Headquarters Zetex GmbH Zetex Inc Zetex Asia Ltd Zetex Semiconductors plc Streitfeldstrae 19 700 Veterans Memorial Hwy 3701 04 Metroplaza Tower 1 Zetex Technology Park D 81673 M nchen Hauppauge NY 11788 Hing Fong Road Kwai Fong Chadderton Oldham OL9 9LL Germany USA Hong Kong United Kingdom Telefon 49 89 45 49 49 0 Telephone 1 631 360 2222 Telephone 852 26100 611 Telephone 44 161 622 4444 Fax 49 89 45 49 49 49 Fax 1 631 360 8222 Fax 852 24250 494 Fax 44 161 622 4446 europe sales zetex com usa sales zetex com asia sales zetex com ha zetex com These offices are supported by agents and distributors in major countries world wide This publication is 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 The Company reserves the right to alter without notice the specification design price or conditions of supply of any product or service For the latest product information log on to www zetex com L ETEX ISSUE 92. Charger Development System SEMICONDUCTORS Transient Protection An additional resistor Rlim can be added in series with Rout figure 1 0 to limit the current from lout Any circuit connected to Vout will be protected from input voltage transients This can be of particular use in automotive applications where load dump and other common transients need to be considered Vin R sense To load Vsense Vsense ZXCT 1009 Figure 1 0 ZXCT1009 with additional current limiting Resistor Rlim Assuming the worst case condition of Vout OV providing a low impedance to a transient the minimum value of Rlim is given by R min Vor Vmax pk Vpk Peak transient voltage to be withstood Vmax Maximum working Voltage 20V lpk Peak output current 40mA The maximum value of Riim is set by Vin min Vout max and the dropout voltage see transfer characteristic on page 3 of the ZXCT1009 R IV min V V out max Ry max V max out Vin min Minimum Supply Operating Voltage Vdp Dropout Voltage Vout max Maximum Operating Output Voltage ISSUE 9 OCTOBER 2005 APPLICATIONS INFORMATION Continued PCB trace shunt resistor for low cost solution The figure below shows output characteristics of the device when using a PCB resistive trace for a low cost solution in replacement for a conventional shunt resistor The graph shows the linear rise in voltage across the resi
3. HIGH SIDE CURRENT MONITOR DESCRIPTION The ZXCT1009 is a high side current sense monitor Using this device eliminates the need to disrupt the ground plane when sensing a load current It takes a high side voltage developed across a current shunt resistor and translates it into a proportional output current A user defined output resistor scales the output current into a ground referenced voltage The wide input voltage range of 20V down to as low as 2 5V make it suitable for a range of applications A minimum operating current of just 44A combined with its SOT23 package make it a unique solution for portable battery equipment FEATURES Low cost accurate high side current sensing e Output voltage scaling Up to 2 5V sense voltage e 2 5V 20V supply range e 4pA quiescent current e 1 typical accuracy e SOT23 and SM8 packages ORDERING INFORMATION DEVICE QUANTITY PER REEL ZXCT1009 APPLICATIONS e Battery chargers e Smart battery packs e DC motor control e Over current monitor e Power management e Level translating e Programmable current source APPLICATION CIRCUIT V in R sense To load Vsense Vsense ZXCT 1009 lout 1 Vout PARTMARKING PACKAGE ZXCT1009FTA 3 000 units 109 SOT23 ZXCT1009T8TA ISSUE 9 OCTOBER 2005 1 000 units ZXCT 1009 SM8 SEMICONDUCTORS ZXCT1009 ABSOLUTE MAXIMUM RATINGS Voltage on any pin 0 6V to 20V relative to lo
4. IT APPLICATION Vi Rsense To load n D 2 3 V sense V sense ZXCT 1009 lout R load 1 Vout Rout Where Rload represents any load including DC motors a charging battery or further circuitry that requires monitoring Rsense can be selected on specific requirements of accuracy size and power rating SEMICONDUCTORS ZXCT1009 APPLICATIONS INFORMATION Continued Charger input FZT789A 1404 H 0 20 To battery NMN p FMMT3904 ZHCS100 5v 10pH bq2954 MOD pin q295 FMMT451 ZXCT1009 lout SNS pin u Support components omitted for clarity k Li lon Charger Circuit The above figure shows the ZXCT1009 supporting the Benchmarq bq2954 Charge Management IC Most of the support components for the bq2954 are omitted for clarity This design also uses the Zetex FZT789A high current Super B PNP as the switching transistor in the DC DC step down converter and the FMMT451 as the drive NPN for the FZT789A The circuit can be configured to charge up to four Li lon cells at a charge current of 1 25A Charge can be terminated on maximum voltage selectable minimum current or maximum time out Switching frequency of the PWM loop is approximately 120kHz The ZXCT1009 is intended as a direct functional replacement for the ZDS 1009 which is featured in a complete design from Unitrode Texas Instruments on the Li lon charger circuit shown above Reference DVS2954S1H Li lon
5. OCTOBER 2005 SEMICONDUCTORS 8
6. ad battery lout Output current proportional to Vin Vioad CONNECTION DIAGRAMS SOT23 SM8 Package Suffix F Package Suffix T8 Vsense m N C Vsense lout Top View Top View ISSUE 9 OCTOBER 2005 SEMICONDUCTORS 4 POWER DISSIPATION The maximum allowable power dissipation of the device for normal operation Pmax is a function of the package junction to ambient thermal resistance 0ja maximum junction temperature Tjmax and ambient temperature Tamb according to the expression Pmax Tjmax Tamb 9ja The device power dissipation PD is given by the expression PD lout Vin Vout Watts 40 a i z 3 0 GE S a o 20 E SM8 o z o a e 1 0 Sor e o 20 40 60 80 100 120 140 160 T Ambient Temperature ISSUE 9 OCTOBER 2005 ZXCT1009 APPLICATIONS INFORMATION The following lines describe how to scale a load current to an output voltage Vsense Vin Vioad Vout 0 01 x Vsense x Rout E g A lA current is to be represented by a 100mV output voltage 1 Choose the value of Rsense to give 50mV Vsense gt 500mV at full load For example Vsense 100mV at 1 0A Rsense 0 1 1 0 2 0 1 ohms 2 Choose Rout to give Vout 100mV when Vsense 100mV Rearranging for Rout gives Rout Vout Vsense x 0 01 Rout 0 1 0 1 x 0 01 100 Q TYPICAL CIRCU
7. stor due to the PTC of the material and demonstrates how this rise in resistance value over temperature compensates for the NTC ofthe device The figure opposite shows a PCB layout suggestion The resistor section is 25mm x 0 25mm giving approximately 150mQ using 10z copper The data for the normalised graph was obtained using a 1A load current and a 100Q output resistor An electronic version of the PCB layout is available at www zetex com isense 1 4 Voltage across Copper Sense o Resistor D o 12 gt 9 Vour with Copper 2 1 0 Sense Resistor c E o Vour With Ideal z 0 8 Sense Resistor 40 20 0 20 40 60 80 100 120 140 Temperature C Effect of Sense Resistor Material on Temperature Performance ISSUE 9 OCTOBER 2005 ZXCT1009 ZXCT1009 Vout Vin Ir a ZXCT1009 Vout Load ND Gi ZETEX Rout Actual Size Layout shows area of shunt resistor compared to SOT23 package Not actual size SEMICONDUCTORS ZXCT1009 PACKAGE DIMENSIONS SOT23 Millimeters Min Max Max 3 05 0 120 1 40 0 055 1 10 0 043 0 37 0 53 0 0145 0 021 0 085 0 15 0 0033 0 0059 NOM 1 9 NOM 0 075 0 01 0 10 0 0004 0 004 2 10 2 50 0 0825 0 0985 STAND OFF HEIGHT K zi iri o m ocoo uo NOM 0 95 NOM 0 037 PACKAGE
8. tput v Sense Voltage Error v Sense Voltage Vin 5V Vin 5V Tamb 25 C RF Piy 20dBm Vsense 1V Rout 02 Gain dB lt c o Fes 2 Oo 2 Q 2 O 2 5 0 20 40 60 80 0 1 1 Temperature C Frequency MHz Output Current v Temperature Frequency Response 0 10 F Vin 5V 20 Tamb 25 C RF Piy 20dBm 30 40 VsEN 50 0 01 60 70 Rejection dB lout Output Current mA 10 100 1k 10k 100k 1M 10M Vin Supply Voltage V Frequency Hz Transfer Characteristic Common Mode Rejection ISSUE 9 OCTOBER 2005 Z FIX 3 SEMICONDUCTORS ZXCT1009 TYPICAL CHARACTERISTICS Cont SCHEMATIC DIAGRAM 5 2 Vsense T 25 i 5 0 RLoad 100 O L CLoad 10pF Voltage V 1009 4 8 4 6 Current A 8 10 12 14 16 18 20 Time us Step Response PIN DESCRIPTION Pin Name Pin Function Vsense4 Supply voltage Vsense Connection to lo
9. ut Continuous output current 25mA Continuous sense voltage Vin 0 5V gt Vsense Vin 5V Operating temperature 40 to 85 C Storage temperature 55 to 125 C Package power dissipation TA 25 C SOT23 450mW derate to zero at 125 C SM8 2W Operation above the absolute maximum rating may cause device failure Operation at the absolute maximum ratings for extended periods may reduce device reliability ELECTRICAL CHARACTERISTICS Test Conditions TA 25 C Vin 5V Rout 1000 SYMBOL PARAMETER CONDITIONS LIMITS Vcc range Output current Vsense 0V Vsense 10mV Vsense 100mV Vsense 200mV Vsense 1V Vsense Sense voltage Isense Vsense input current Acc Accuracy Rsense 0 12 Vsense 200mV Transconductance lout Vsense Bandwidth RF Pin 20dBmt Vsense 10mV dc Vsense 100mV dc Includes input offset voltage contribution Vsense Vin Vload t 20dBm 63mVp p into 50Q ISSUE 9 OCTOBER 2005 SEMICONDUCTORS 2 ZXCT1009 TYPICAL CHARACTERISTICS 100u 10u lout Output Current A Output Current Error 100u 1m 10m 100m 100m Vsense V Vsense V Typical Ou
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