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A Product Line of Diodes Incorporated ZXGD3102T8 ACTIVE OR'ING CONTROLLER Description The ZXGD3102 is intended to drive MOSFETS configured as ideal diode replacements. The device is comprised of a differential amplifier detector stage and high current driver. The detector monitors the reverse voltage of the MOSFET such that if body diode conduction occurs a positive voltage is applied to the MOSFET's Gate pin. Once the positive voltage is applied to the Gate the MOSFET switches on allowing reverse current flow. The detectors' output voltage is then proportional to the MOSFET Drain-Source reverse voltage drop and this is applied to the Gate via the driver. This action provides a rapid turn off as current decays. Features * * * * * * Applications * * * Turn-off time typically 160ns 180V blocking voltage Proportional Gate drive 2A Source, 5A Sink driver VCC Range 5-15V Low component count High Side OR'ing diode replacement for Servers, Computer Low Side OR'ing Telecoms diode replacement for Ideal diode applications Pin out details Typical Configuration N/C REF GATEL GATEH 1 2 3 4 8 7 6 5 DRAIN BIAS GND VCC SM8 Ordering information Device ZXGD3102T8TA Status Active Package SM8 Part Mark ZXGD3102 Reel size (inches) 7 Tape width (mm) 12 Quantity per reel 1000 Issue 3, January 2009 (c) Diodes Incorporated 2008 1 www.diodes.com ZXGD3102T8 Absolute maximum ratings Parameter Supply voltage1 Continuous Drain pin voltage1 GATEH and GATEL output Voltage1 Driver peak source current Driver peak sink current Reference current Bias voltage Bias current Power dissipation at TA =25C Operating junction temperature Storage temperature Notes: Symbol VCC VD VG ISOURCE ISINK IREF VBIAS IBIAS PD Tj Tstg Limit 15 -3 to180 -3 to VCC + 3 4 7 25 VCC 100 500 -40 to +150 -50 to +150 Unit V V V A A mA V mA mW C C 1. All voltages are relative to GND pin Thermal resistance Parameter Junction to ambient (*) Junction to case () Symbol RJA RJC Value 250 54 Unit C/W C/W Notes: (*) Mounted on minimum 1oz copper on FR4 PCB in still air conditions () Output Drivers - Junction to solder point at the end of the lead 5 and 6 ESD Rating Model Human body Machine Rating 4,000 400 Unit V V Issue 3, January 2009 (c)Diodes Incorporated 2008 2 www.diodes.com ZXGD3102T8 DC Electrical characteristics at TA = 25C; VCC = 10V; RBIAS = 3.3k ; RREF=3.9k Parameter Symbol Conditions Min. Typ Max. Unit Input and supply characteristics Operating current Gate Driver Turn-off Threshold Voltage(**) VT VG(off) GATE output voltage (**) VG VG = 1V, (*) VDRAIN 0V, (*) VDRAIN = -60mV, ( ) VDRAIN = -80mV, ( ) VDRAIN = -100mV, ( ) VDRAIN = -140mV, ( ) GATEH peak source current GATEL peak sink current ISOURCE ISINK VGH = 1V VGL = 5V 5 -50 4.1 6.5 8.0 8.5 -24 0.58 7 8.5 9 9.4 2 0 1 A A V mV IOP VDRAIN -100m V VDRAIN 0V 2.4 5.2 mA - DC Electrical Characteristics at TA = 25C; VCC = 10V; RBIAS = 3.9k ; RREF=3.9k Parameter Symbol Conditions Min. Typ Max. Unit Input and supply characteristics Operating current Gate Driver Turn-off Threshold Voltage(**) VT VG(off) GATE output voltage (**) VG VG = 1V, (*) VDRAIN 0V, (*) VDRAIN = -60mV, ( ) VDRAIN = -80mV, ( ) VDRAIN = -100mV, ( ) VDRAIN = -140mV, ( ) GATEH peak source current GATEL peak sink current Notes: (**) GATEH connected to GATEL (*) RH = 100k, RL = O/C ( ) RL = 100k, RH = O/C ISOURCE ISINK VGH = 1V VGL = 5V 5 -55 3.5 6.5 8.0 8.5 -29 0.57 6.5 8.5 8.8 9.4 2 0 1 A A V mV IOP VDRAIN -100m V VDRAIN 0V 2.4 4.8 mA - Issue 3, January 2009 (c)Diodes Incorporated 2008 3 www.diodes.com ZXGD3102T8 Transient Electrical Characteristics at TA = 25C; VCC = 10V; RBIAS = 3.3 k to 3.9k ; RREF=3.9k Turn on Propagation delay Turn off Propagation delay Gate rise time Gate fall time td1 td2 tr tf CL = 10nF,, CBIAS = 2.2nF, ( )(a) 880 52 5100 110 ns ns ns ns (a) Refer to Fig 4: test circuit and Fig 5: timing diagram Schematic Symbol and Pin Out Details Pin No. 1 2 3 4 5 Symbol NC REF GATEL GATEH VCC Description and function No connection This pin can be connected to GND Reference This pin is connected to VCC via resistor, RREF. RREF should be selected to source approximately 2.4mA into this pin. See Note 1 Gate turn off This pin sinks current, ISINK, from the OR'ing MOSFET Gate. Gate turn on This pin sources current, ISOURCE, to the OR'ing MOSFET Gate. Power Supply This is the supply pin. It is recommended to decouple this point to ground closely with a ceramic capacitor. Ground This is the ground reference point. Connect to the OR'ing MOSFET Source terminal. Bias This pin is connected to VCC via resistor, RBIAS. RBIAS should be selected to source 1.2 times IREF into this pin. See Note 1 Drain connection This pin connects directly to the OR'ing MOSFET Drain terminal. 6 GND 7 8 BIAS DRAIN Note 1- BIAS and REF pins should be assumed to be at GND+0.7V. Issue 3, January 2009 (c)Diodes Incorporated 2008 4 www.diodes.com ZXGD3102T8 Operation The operation of the device is described step-by-step with reference to the timing diagram below. 1. The detector monitors the MOSFET Drain-Source voltage. 2. At system start up, the MOSFET body diode is forced to conduct current from the input power supply to the load and there is approximately -0.6V on the Drain pin. 3. The detector outputs a positive voltage with respect to ground, this voltage is then fed to the MOSFET driver stage and current is sourced out of the GATEH pin. The turn on time of the MOSFET can be programmed through an external resistor RG. Refer to "Speed vs. Gate resistance" graph. 4. The current out of the GATEH pin is sourced into the OR'ing MOSFET Gate to turn the device on. 5. The GATEH output voltage is proportional to the Drain-Source voltage drop across the MOSFET due to the load current flowing through the MOSFET. The controller increases its output gate voltage when the Drain current is high to ensure full MOSFET enhancement 6. If a short condition occurs on the input power supply it causes the OR'ing MOSFET Drain current to fall very quickly. 7. When the Drain-Source differential voltage drops below the turn off threshold, the MOSFET Gate voltage is pulled low by GATEL, turning the device off. This prevents high reverse current flow from the load to the input power supply which could pull down the common bus voltage causing catastrophic system failure MOSFET Drain Voltage MOSFET Gate Voltage MOSFET Gate Current Issue 3, January 2009 (c)Diodes Incorporated 2008 5 www.diodes.com ZXGD3102T8 Typical characteristics 10 16 VG Gate Voltage (V) 8 6 4 2 VCC=10V RBIAS=3.3k RREF=3.9k RLOAD=100k VG Gate Voltage (V) T = -40C T = 25C T = 125C 14 12 10 8 6 4 2 RBIAS=3.3k RREF=3.9k RLOAD=100k T = 25C VCC = 16V VCC = 14V VCC = 12V VCC = 10V VCC = 8V VCC = 6V 0 -0.14 -0.12 -0.10 -0.08 -0.06 -0.04 -0.02 0.00 0 -0.14 -0.12 -0.10 -0.08 -0.06 -0.04 -0.02 0.00 VD Drain Voltage (V) VD Drain Voltage (V) Transfer Characteristic 10 16 Transfer Characteristic VG Gate Voltage (V) 8 6 4 2 VCC=10V RBIAS=3.9k RREF=3.9k RLOAD=100k VG Gate Voltage (V) T = -40C T = 25C T = 125C 14 12 10 8 6 4 2 RBIAS=3.9k RREF=3.9k RLOAD=100k T = 25C VCC = 16V VCC = 14V VCC = 12V VCC = 10V VCC = 8V VCC = 6V 0 -0.14 -0.12 -0.10 -0.08 -0.06 -0.04 -0.02 0.00 -0.14 -0.12 -0.10 -0.08 -0.06 -0.04 -0.02 0.00 VD Drain Voltage (V) VD Drain Voltage (V) Transfer Characteristic VD Drain Turn-Off Voltage (mV) -15 -20 RBIAS=3.3k Transfer Characteristic -25 -30 -35 -40 -45 -50 -50 VCC = 10V ISINK=1mA VG = 1V RBIAS=3.9k RREF=3.9k RREF=3.9k -25 0 25 50 75 100 125 150 Temperature (C) Turn-Off Voltage vs Temperature Issue 3, January 2009 (c)Diodes Incorporated 2008 6 www.diodes.com ZXGD3102T8 Typical characteristics 10 8 VCC=10V VG 10 8 VG VCC=10V RBIAS=3.9k RREF=3.9k CLOAD=3.3nF VD RLOAD=100k Voltage (V) 6 4 2 0 0 5 VD Voltage (V) 30 RBIAS=3.9k RREF=3.9k CLOAD=3.3nF RLOAD=100k 6 4 2 0 10 15 20 25 0.0 0.1 0.2 0.3 0.4 0.5 Time (s) Time (s) Switch-On Speed 11.4 11.2 11 10.8 10.6 10.4 0.16 0.14 0.12 0.10 0.08 -50 -25 0 25 50 75 toff Switch-Off Speed 5.25 Supply Current (mA) ton 5.20 5.15 IOFF VCC=10V RBIAS=3.9k RREF=3.9k RLOAD=100k Time (s) VCC=10V RBIAS=3.9k RREF=3.9k CBIAS=1.0nF CLOAD=3.3nF RLOAD=100k 2.95 2.90 2.85 2.80 -50 -25 0 25 50 ION 100 125 150 75 100 125 150 Temperature (C) Temperature (C) Speed vs Temperature Supply Current vs Temperature Issue 3, January 2009 (c)Diodes Incorporated 2008 7 www.diodes.com ZXGD3102T8 Typical characteristics 10 8 VCC=10V VG 10 8 VG VCC=10V RBIAS=3.3k RREF=3.9k CBIAS=1.0nF CLOAD=3.3nF VD RLOAD=100k Voltage (V) 6 4 2 0 0 5 VD RREF=3.9k CBIAS=1.0nF CLOAD=3.3nF RLOAD=100k Voltage (V) 30 RBIAS=3.3k 6 4 2 0 10 15 20 25 0.0 0.1 0.2 0.3 0.4 0.5 Time (s) Time (s) Switch-On Speed 10.2 10 9.8 9.6 9.4 9.2 0.16 0.14 0.12 0.10 0.08 -50 -25 0 25 50 75 toff Switch-Off Speed 5.65 ton Supply Current (mA) 5.60 5.55 IOFF VCC=10V RBIAS=3.3k RREF=3.9k RLOAD=100k Time (s) VCC=10V RBIAS=3.3k RREF=3.9k CBIAS=1.0nF CLOAD=3.3nF RLOAD=100k 2.95 2.90 2.85 2.80 -50 -25 0 25 50 ION 100 125 150 75 100 125 150 Temperature (C) Temperature (C) Speed vs Temperature Supply Current vs Temperature Issue 3, January 2009 (c)Diodes Incorporated 2008 8 www.diodes.com ZXGD3102T8 Component Selection It is advisable to decouple the ZXGD3102 closely to VCC and ground due to the possibility of high peak gate currents, as indicated by C1 in Figure 4. In applications where the input voltage is higher than 12V, it is recommended to use a zener diode, ZD1 as shown in the Typical Application Circuit on page 1, and in Figure 2, in order to limit the VCC supply voltage to the ZXGD3102 and also to limit the maximum voltage applied to the gate of the MOSFET. A suitable value for the zener is 10V. The proper selection of external resistors RREF and RBIAS is important to the optimum device operation. Select a value for resistor RREF to give a reference current, IREF, of ~2.4mA. The value of RBIAS must then be ~1.2 times the value of RREF to give a bias current, IBIAS, of 1.2 times IREF . External gate resistors are optional. They can be inserted to control the rise times which may help with EMI issues, power supply consumption issues or dissipation within the part. RREF = (VCC -0.7V)/ 0.0024 RBIAS = (VCC -0.7V)/ 0.0028 The addition of CBIAS controls the switch-on delay of the MOSFET, and ensures stability. A suitable value is 1nF. Layout considerations The Gate pins should be as close to the MOSFET Gate as possible. Also the ground return loop should be as short as possible. The decoupling capacitor should be close to the VCC and Ground pin, and should be a X7R type. Trace widths should be maximized in the high current path through the MOSFET and ground return in order to minimize the effects of circuit inductance and resistance. Issue 3, January 2009 (c)Diodes Incorporated 2008 9 www.diodes.com ZXGD3102T8 Active OR'ing or N+1 redundancy In normal operation, power supply A and B share the load for maximum reliability. Power supply A supports the load if power supply B fails and vice versa. Blocking diodes protect the load from a faulty power supply affecting the load voltage. The load can be tens of amps. Dissipation in the diodes can be high! The ZXGD3102 is designed to switch the low on-resistance MOSFETs used to replace the blocking diodes. Figure 1: OR'ING with Schottky Diodes Issue 3, January 2009 (c)Diodes Incorporated 2008 10 www.diodes.com ZXGD3102T8 Figure 2: Negative telecom active OR'ing evaluation Issue 3, January 2009 (c)Diodes Incorporated 2008 11 www.diodes.com ZXGD3102T8 Figure 3: Positive rail power supply active OR'ing evaluation Issue 3, January 2009 (c)Diodes Incorporated 2008 12 www.diodes.com ZXGD3102T8 Figure 4: Test Circuit Figure 5: Timing Diagram Issue 3, January 2009 (c)Diodes Incorporated 2008 13 www.diodes.com ZXGD3102T8 Issue 3, January 2009 (c)Diodes Incorporated 2008 14 www.diodes.com ZXGD3102T8 IMPORTANT NOTICE Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to any product herein. Diodes Incorporated does not assume any liability arising out of the application or use of any product described herein; neither does it convey any license under its patent rights, nor the rights of others. The user of products in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on our website, harmless against all damages. Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels. LIFE SUPPORT Diodes Incorporated 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. Issue 3, January 2009 (c)Diodes Incorporated 2008 15 www.diodes.com |
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