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 105ns • • 180V blocking voltage High Side OR’ing diode replacement for Servers, Computer • Proportional Gate drive • Low Side OR’ing Telecoms • 2A Source, 5A Sink driver • Ideal diode applications • VCC Range 5-15V • Low component count Pin out details replacement for Typical Configuration N/C 1 REF diode 8 DRAIN 2 7 BIAS GATEL 3 6 GND GATEH 4 5 VCC SM8 Ordering information Device Status Package Part Mark Reel size (inches) Tape width (mm) Quantity per reel ZXGD3102T8TA Active SM8 ZXGD3102 7 12 1000 Issue 4, May 2009 © Diodes Incorporated 2008 1 www.diodes.com ZXGD3102T8 Absolute maximum ratings Parameter Symbol Limit Unit Supply voltage1 VCC 15 V Continuous Drain pin voltage1 VD -3 to180 V GATEH and GATEL output Voltage1 VG -3 to VCC + 3 V ISOURCE 4 A Driver peak sink current ISINK 7 A Reference current IREF 25 mA Bias voltage VBIAS VCC V Bias current IBIAS 100 mA Power dissipation at TA =25°C PD 500 mW Operating junction temperature Tj -40 to +150 °C Tstg -50 to +150 °C Symbol Value Unit Junction to ambient (*) RθJA 250 °C/W Junction to case (†) RθJC 54 °C/W Driver peak source current Storage temperature Notes: 1. All voltages are relative to GND pin Thermal resistance Parameter Notes: (*) Mounted on minimum 1oz copper on FR4 PCB in still air conditions (†) Junction to solder point at the end of the lead 5 and 6 ESD Rating Model Rating Unit Human body 4,000 V 400 V Machine Issue 4, May 2009 ©Diodes Incorporated 2008 2 www.diodes.com ZXGD3102T8 DC Electrical characteristics at TA = 25°C; VCC = 10V; RBIAS = 3.3kΩ; RREF=3.9kΩ Parameter Symbol Conditions Min. Typ Max. Unit Input and supply characteristics Operating current IOP VD ≤ -100m V - 2.4 - VD ≥ 0V - 5.2 - mA Gate Driver Turn-off Threshold Voltage(**) VT VG = 1V, (*) -50 -24 0 VG(off) VD ≥ 0V, (*) - 0.58 1 VD = -60mV, (g) 4.1 7 - VD = -80mV, (g) 6.5 8.5 - VD = -100mV, (g) 8.0 9 - VD = -140mV, (g) 8.5 9.4 - 2 - A - - A Typ Max. Unit GATE output voltage (**) VG GATEH peak source current ISOURCE VGH = 1V ISINK VGL = 5V GATEL peak sink current 5 mV V DC Electrical Characteristics at TA = 25°C; VCC = 10V; RBIAS = 3.9kΩ; RREF=3.9kΩ Parameter Symbol Conditions Min. Input and supply characteristics Operating current IOP VD ≤ -100m V (g) - 2.4 - VD ≥ 0V (*) - 4.8 - mA Gate Driver VT VG = 1V, (*) -55 -29 0 VG(off) VD ≥ 0V, (*) - 0.57 1 VD = -60mV, (g) 3.5 6.5 - VD = -80mV, (g) 6.5 8.5 - VD = -100mV, (g) 8.0 8.8 - VD = -140mV, (g) 8.5 9.4 - 2 - A - - A Turn-off Threshold Voltage(**) GATE output voltage (**) VG GATEH peak source current GATEL peak sink current ISOURCE VGH = 1V ISINK VGL = 5V 5 mV V Notes: (**) GATEH connected to GATEL (*) RH = 100kΩ, RL = O/C; RH needed only for characterization purposes, not in the application (g) RL = 100kΩ, RH = O/C; RL needed only for characterization purposes, not in the application Issue 4, May 2009 ©Diodes Incorporated 2008 3 www.diodes.com ZXGD3102T8 Transient Electrical Characteristics at TA = 25°C; VCC = 10V; RBIAS = 3.9k ; RREF=3.9k Turn on Propagation delay td1 Turn off Propagation delay td2 Gate rise time tr Gate fall time tf CL = 3.3nF, CBIAS = 1nF, (g)(a) 1880 ns 30 ns 9520 ns 75 ns 1940 ns 32 ns 9840 ns 78 ns VCC = 10V; RBIAS = 3.9k ; RREF=3.9k Turn on Propagation delay td1 Turn off Propagation delay td2 Gate rise time tr Gate fall time tf CL = 10nF, CBIAS = 1nF, (g)(a) (a) Refer to Fig 4: test circuit and Fig 5: timing diagram Schematic Symbol and Pin Out Details Pin No. Symbol 1 NC 2 REF 3 GATEL 4 GATEH 5 VCC 6 GND 7 BIAS 8 DRAIN 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. Decouple this point to ground 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 RBIAS. RBIAS should be selected to source either 1 or 1.2 times IREF into this pin depending on the desired turn-off threshold voltage, VT. See Note 1 Drain connection This pin connects directly to the OR’ing MOSFET Drain terminal Note 1- BIAS and REF pins should be assumed to be at GND+0.7V. Issue 4, May 2009 ©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 4, May 2009 ©Diodes Incorporated 2008 5 www.diodes.com ZXGD3102T8 Typical characteristics 16 T = -40°C T = 25°C T = 125°C 8 6 4 VCC=10V RBIAS=3.3kΩ 2 RREF=3.9kΩ RLOAD=100kΩ VG Gate Voltage (V) VG Gate Voltage (V) 10 0 -0.14 -0.12 -0.10 -0.08 -0.06 -0.04 -0.02 0.00 VCC = 8V 6 VCC = 6V 4 2 RBIAS=3.3kΩ RREF=3.9kΩ RLOAD=100kΩ T = 25°C VD Drain Voltage (V) Transfer Characteristic 16 T = -40°C T = 25°C T = 125°C 8 6 VCC=10V RBIAS=3.9kΩ RREF=3.9kΩ RLOAD=100kΩ VG Gate Voltage (V) VG Gate Voltage (V) VCC = 10V 8 0 -0.14 -0.12 -0.10 -0.08 -0.06 -0.04 -0.02 0.00 10 14 VCC = 15V 12 VCC = 14V VCC = 12V 10 VCC = 10V 8 VCC = 8V 6 VCC = 6V 4 2 RBIAS=3.9kΩ RREF=3.9kΩ RLOAD=100kΩ T = 25°C 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) VCC = 12V 10 Transfer Characteristic 2 VCC = 14V 12 VD Drain Voltage (V) 4 VCC = 15V 14 Transfer Characteristic -15 -20 RBIAS=3.3kΩ RREF=3.9kΩ -25 -30 -35 -40 -45 -50 -50 VCC = 10V RBIAS=3.9kΩ ISINK=1mA RREF=3.9kΩ VG = 1V -25 0 25 50 75 100 125 150 Temperature (°C) Turn-Off Voltage vs Temperature Issue 4, May 2009 ©Diodes Incorporated 2008 6 www.diodes.com ZXGD3102T8 Typical characteristics 10 10 6 RBIAS=3.9kΩ VG RREF=3.9kΩ CLOAD=3.3nF 4 RLOAD=100kΩ VD 2 VG 8 VCC=10V Voltage (V) Voltage (V) 8 0 RBIAS=3.9kΩ RREF=3.9kΩ CLOAD=3.3nF 4 2 5 10 15 20 25 30 0.0 0.1 Time (μs) RBIAS=3.9kΩ RREF=3.9kΩ CBIAS=1.0nF CLOAD=3.3nF RLOAD=100kΩ 0.12 0.10 0.08 -50 toff -25 0 25 50 75 Supply Current (mA) Time (μs) 0.14 100 125 150 0.5 4.95 VCC=10V 4.90 RREF=3.9kΩ RBIAS=3.9kΩ RLOAD=100kΩ 2.65 2.60 2.55 ION -25 0 25 50 75 100 125 150 Temperature (°C) Supply Current vs Temperature Speed vs Temperature ©Diodes Incorporated 2008 0.4 IOFF 5.00 2.50 -50 Temperature (°C) Issue 4, May 2009 0.3 Switch-Off Speed ton VCC=10V 0.2 Time (μs) Switch-On Speed 0.16 RLOAD=100kΩ VD 0 0 11.6 11.4 11.2 11 10.8 VCC=10V 6 7 www.diodes.com ZXGD3102T8 Typical characteristics 10 10 VCC=10V 8 Voltage (V) Voltage (V) RREF=3.9kΩ VG 6 CBIAS=1.0nF 4 CLOAD=3.3nF RLOAD=100kΩ VD 2 0 RBIAS=3.3kΩ RREF=3.9kΩ 6 CBIAS=1.0nF 4 CLOAD=3.3nF VD 5 10 15 20 25 30 0.0 0.1 Time (μs) 0.4 0.5 5.50 ton VCC=10V Supply Current (mA) Time (μs) 0.3 Switch-Off Speed RBIAS=3.3kΩ RREF=3.9kΩ CBIAS=1.0nF CLOAD=3.3nF RLOAD=100kΩ 0.14 0.12 0.10 0.08 -50 0.2 Time (μs) Switch-On Speed 0.16 RLOAD=100kΩ 2 0 0 10 9.8 9.6 9.4 9.2 9 8.8 VCC=10V VG 8 RBIAS=3.3kΩ toff -25 0 25 50 75 100 125 150 VCC=10V 5.35 RBIAS=3.3kΩ RREF=3.9kΩ RLOAD=100kΩ 2.65 2.60 2.55 ION -25 0 25 50 75 100 125 150 Temperature (°C) Supply Current vs Temperature Speed vs Temperature ©Diodes Incorporated 2008 5.40 2.50 -50 Temperature (°C) Issue 4, May 2009 IOFF 5.45 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 selected to give a bias current, IBIAS, of approximately 1.2 times IREF. This set the turn-off threshold voltage VT of the controller to ‘-24mV’ at VCC =10V. RREF = (VCC -0.7V)/ 0.0024 RBIAS = (VCC -0.7V)/ 0.0028 Alternatively, RREF and RBIAS can be chosen to be equal to set the turn-off threshold voltage VT to ‘29mV’ at VCC =10V. This also reduces the IC current consumption when the gate voltage is off. External gate resistor to GATEH pin is optional. It can be inserted to control the turn-on gate rise time which may help with in-rush current protection, EMI issues or power dissipation within the part. 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. For best thermal performance, the PCB heat path from pins 5 and 6 needs attention. The area of copper connected to pins 5 and 6 should be maximised. Issue 4, May 2009 ©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 4, May 2009 ©Diodes Incorporated 2008 10 www.diodes.com ZXGD3102T8 Figure 2: Negative telecom active OR’ing evaluation Issue 4, May 2009 ©Diodes Incorporated 2008 11 www.diodes.com ZXGD3102T8 OR’ing MOSFET 30V Common bus 10V supply Vcc G D RREF REF POWER SUPPLY A RBIAS BIAS Vcc LOAD ZXGD3102 DRAIN CBIAS GATEL GATEH GND S RG 0V OR’ing MOSFET 30V Vcc G D RREF REF POWER SUPPLY B DRAIN RBIAS BIAS Vcc ZXGD3102 CBIAS GATEL GATEH GND RG S 0V Figure 3: Positive rail power supply active OR’ing evaluation Issue 4, May 2009 ©Diodes Incorporated 2008 12 www.diodes.com ZXGD3102T8 Figure 4: Test Circuit Figure 5: Timing Diagram Issue 4, May 2009 ©Diodes Incorporated 2008 13 www.diodes.com ZXGD3102T8 Issue 4, May 2009 ©Diodes Incorporated 2008 14 www.diodes.com ZXGD3102T8 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). 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