A Product Line of Diodes Incorporated ZXGD3103N8 SYNCHRONOUS MOSFET CONTROLLER Description The ZXGD3103 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 • Proportional Gate Drive • • Turn-off propagation delay 15ns and turn-off time 20ns. • Detector threshold voltage ~10mV • Standby current 5mA • Suitable for Discontinuous Mode (DCM), Critical Conduction Mode (CrCM) and Continuous Mode (CCM) operation • Flyback Converters in: • Adaptors • LCD Monitors • Server PSU’s • Set Top Boxes • LCD TV • Resonant Converters • LED TV 5-15V VCC range • High power Adaptors • Street Lighting • ATX psu Pin out details Typical Configuration N/C 1 8 DRAIN REF 2 7 BIAS GATEL 3 6 GND GATEH 4 5 VCC SO-8 Ordering information Device Status ZXGD3103N8TC Production ZXGD3103N8 Document number: DS32255 Rev. 2 - 2 Package Part Mark Reel size (inches) Tape width (mm) Quantity per reel SO8 ZXGD3103 13 12 2500 1 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 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 2.5 A Driver peak sink current ISINK 6 A Reference current IREF 25 mA Bias voltage VBIAS VCC V Bias current IBIAS 100 mA Power dissipation at TA =25°C PD 490 mW Operating junction temperature Tj -40 to +150 °C Tstg -50 to +150 °C Symbol Value Unit Junction to ambient (a) RθJA 255 °C/W Junction to lead (b) RθlA 120 °C/W Driver peak source current Storage temperature Notes: 1. All voltages are relative to GND pin. Thermal resistance Parameter Notes: a. Mounted on minimum 1oz weight copper on FR4 PCB in still air conditions. b. Output Drivers - Junction to solder point at end of the lead 5 and 6 ESD Rating Model Rating Unit Human Body 4000 V Machine 400 V ZXGD3103N8 Document number: DS32255 Rev. 1 - 2 2 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 Electrical characteristics at TA = 25°C; VCC = 10V; RBIAS = 3.3kΩ; RREF= 4.3kΩ Parameter Symbol Conditions Min. Typ. Max. Unit Input and supply characteristics Operating current IOP VD ≤ -200m V - 2.16 - VD ≥ 0V - 5.16 - mA Gate Driver Turn-off Threshold Voltage(**) VT VG = 1V, (*) -16 -10 0 VG(off) VD ≥ 0V, (*) - 0.73 1 VD = -50mV, (g) 6.0 7.2 - VD = -100mV, (g) 8.8 9.2 - VD ≤ -150mV, (g) 9.2 9.4 - VD ≤ -200mV, (g) 9.3 9.5 - GATE output voltage (**) VG mV V Switching performance (“) for QG(tot) = 82nC Turn on Propagation delay 150 td1 Turn off Propagation delay td2 Gate rise time tr Gate fall time tf Refer to switching waveforms in Fig. 3 15 450 Continuous Conduction Mode 21 Discontinuous Conduction Mode 17 ns Notes: (**) GATEH connected to GATEL (*) RH = 100kΩ, RL = O/C (g) RL = 100kΩ, RH = O/C (“) refer to test circuit below ZXGD3103N8 Document number: DS32255 Rev. 1 - 2 3 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 Schematic Symbol and Pin Out Details Pin No. Name Description and function 1 NC No Internal connection 2 REF 3 GATEL 4 GATEH 5 VCC 6 GND 7 BIAS 8 DRAIN Reference This pin is connected to VCC via resistor, RREF Gate turn off This pin sinks current, ISINK, from the synchronous MOSFET Gate. Gate turn on This pin sources current, ISOURCE, to the synchronous 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 synchronous MOSFET Source terminal. Bias This pin is connected to VCC via resistor, RBIAS. Drain connection This pin connects directly to the synchronous MOSFET Drain terminal. ZXGD3103N8 Document number: DS32255 Rev. 2 - 2 4 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 Typical Characteristics 10 VCC = 15V 12 VCC = 12V 10 VCC = 10V VCC = 5V 8 6 4 2 VG Gate Voltage (V) VG Gate Voltage (V) 14 8 T T T T 6 4 VCC = 10V RBIAS=3K3 2 RREF=4K3 100k pull down See Resistor Table for Values 0 -100 -80 -60 -40 -20 0 -100 0 VD Drain Voltage (mV) -60 -40 -20 0 Transfer Characteristic 5 100 VCC = 10V 0 RBIAS=3K3 RREF=4K3 -5 VG = 1V -10 100k pull up -15 -20 -25 -50 -25 0 25 50 75 Supply Current (mA) VD Drain Voltage (mV) -80 VD Drain Voltage (mV) Transfer Characteristic VCC = 10V RBIAS=3k3 RREF=4K3 D = 0.5 CLOAD=22nF CLOAD=10nF CLOAD=4.7nF CLOAD=2.2nF CLOAD=1nF 10 100 125 150 1k 10k Temperature (°C) 100k Frequency (Hz) Drain Sense Voltage vs Temperature Supply Current vs Frequency 1 100 RBIAS=3k3 80 RREF=4K3 60 D = 0.5 f=250kHz 0 VCC = 15V VCC = 12V 40 VCC = 10V 20 VCC = 5V Peak Current (A) Supply Current (mA) = -40°C = 25°C = 85°C = 125°C Current flow Supply to Gate -1 VCC = 10V -2 RBIAS=3K3 -3 RREF=4K3 T = 25°C -4 -5 Current flow Gate to Ground 0 0 2 4 6 8 10 12 14 16 18 20 22 Capacitance (nF) Document number: DS32255 Rev. 1 - 2 5 10 15 20 25 Capacitance (nF) Supply Current vs Capacitive Load ZXGD3103N8 0 5 of 12 www.diodes.com Gate Current vs Capacitive Load July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 10 10 8 8 RBIAS=10k 6 CLOAD=10nF Voltage (V) Voltage (V) Typical Characteristics VCC=10V 6 RBIAS=3k3 VG 4 RREF=4K3 VD CLOAD=10nF 2 0 VCC=10V RREF=4K7 4 2 VD VG 0 -2 -0.5 0.0 0.5 1.0 -2 1.5 -40 -20 0 Time (μs) Time (ns) Switch On Speed Switch Off Speed 2 VCC=10V Gate Current (A) Gate Current (A) 0.3 RBIAS=3k3 RREF=4K3 0.2 CLOAD=10nF 0.1 0.0 -0.5 0.0 0.5 1.0 1 0 -1 -2 VCC=10V -3 RREF=4K3 -4 CLOAD=10nF 1.5 Time (μs) Percent Change Time (%) VCC=10V RBIAS=3k3 -40 -20 0 20 40 60 80 100 120 140 Time (ns) Gate Drive On Current 6 20 40 60 80 100 120 140 Gate Drive Off Current tON= tD + tR RBIAS=3k3 RREF=4K3 4 CLOAD=10nF 2 tOFF= tD + tF 0 -2 -50 -25 0 25 50 75 100 125 150 Temperature (°C) Switching vs Temperature ZXGD3103N8 Document number: DS32255 Rev. 1 - 2 6 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 Application information The purpose of the ZXGD3103 is to drive a MOSFET as a low-VF Schottky diode replacement in offline power converters. When combined with a low RDS(ON) MOSFET, it can yield significant power efficiency improvement, whilst maintaining design simplicity and incurring minimal component count. Figure 1 and 2 show typical configuration of ZXGD3103 for synchronous rectification in a Flyback and a multiple output resonant converter. Figure 1. Example connections in Flyback supply Figure 2. Example connections in LLC supply ZXGD3103N8 Document number: DS32255 Rev. 1 - 2 7 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 Descriptions of the normal operation The operation of the device is described step-by-step with reference to the timing diagram in Figure 3. 1. The detector monitors the MOSFET Drain-Source voltage. 2. When, due to transformer action, the MOSFET body diode is forced to conduct there is approximately 0.8V 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 GATE pin. 4. The controller goes into proportional gate drive control — the GATE output voltage is proportional to the on-resistance-induced Drain-Source voltage drop across the MOSFET. Proportional gate drive ensures that MOSFET conducts for majority of the conduction cycle and minimizes body diode conduction time. 5. As the Drain current decays linearly toward zero, proportional gate drive control reduces the Gate voltage so the MOSFET can be turned off rapidly at zero current crossing. The GATE voltage is removed when the Drain-Source voltage crosses the detection threshold voltage to minimize reverse current flow. 6. At zero Drain current, the controller GATE output voltage is pulled low to VG(off) to ensure that the MOSFET is off. Figure 4 shows typical operating waveforms for ZXGD3103 driving a MOSFET with Qg(TOT) = 82nC in a Flyback converter operating in critical conduction mode. Figure 3. Timing diagram for a critical conduction mode Flyback converter ZXGD3103N8 Document number: DS32255 Rev. 1 - 2 8 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 Typical waveforms Fig 4a: Critical conduction mode Voltage (V) Switch On Speed 10 9 8 7 6 VD 5 VG 4 3 2 1 0 -1 -2 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 VCC = 10V RBIAS = 3K3 RREF = 4K3 Qg(TOT) = 82nC 1.0 1.2 1.4 1.6 Time (μs) Fig 4b: Typical switch ON speed when driving a Qg(TOT) = 82nC MOSFET Switch OFF Speed 10 9 8 Voltage (V) 7 VD VCC = 10V 6 RBIAS = 3K3 5 RREF = 4K3 4 Qg(TOT) = 82nC 3 VG 2 1 0 -1 -2 -0.05 -0.04 -0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 0.04 0.05 Time (μs) Fig 4c: Typical switch OFF speed when driving a Qg(TOT) = 82nC MOSFET ZXGD3103N8 Document number: DS32255 Rev. 1 - 2 9 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 Design considerations It is advisable to decouple the ZXGD3103 closely to VCC and ground due to the possibility of high peak gate currents with a 1μF X7R type ceramic capacitor as shown in Figure 2. The Gate pins should be as close to the MOSFET’s gate as possible. Also the ground return loop should be as short as possible. To minimize parasitic inductance-induced premature turn-off issue of the synchronous controller always keep the PCB track length between ZXGD3101’s Drain input and MOSFET’s Drain to less than 10mm. Low internal inductance MOSFET packages such as SO-8 and PolarPak are also recommended for high switching frequency power conversion to minimize body diode conduction. R1, Q1 D1 and C1 in Figure 1 are only required as a series drop-down regulator to maintain a stable Vcc around 10V from a power supply output voltage greater than 15V. External gate resistors are optional. They can be inserted to control the rise and fall time which may help with EMI issues. The proper selection of external resistors RREF and RBIAS is important to the optimum device operation. Select a value for resistor RREF and RBIAS from Table 1 based on the desired Vcc value. This provides the typical ZXGD3103’s detection threshold voltage of 10mV. Table 1. Recommended resistor values for various supply voltages VCC 5V 10V 12V 15V ZXGD3103N8 Document number: DS32255 Rev. 1 - 2 RBIAS 1K6 3K3 3K9 5K1 10 of 12 www.diodes.com RREF 2K0 4K3 5K1 6K8 July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 Package Outline and Dimensions ZXGD3103N8 Document number: DS32255 Rev. 1 - 2 11 of 12 www.diodes.com July 2010 © Diodes Incorporated A Product Line of Diodes Incorporated ZXGD3103N8 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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