Si9912 Vishay Siliconix Half-Bridge MOSFET Driver for Switching Power Supplies FEATURES D D D D D D D D D D APPLICATIONS 4.5- to 5.5-V Operation Undervoltage Lockout 250-kHz to 1-MHz Switching Frequency Shutdown Quiescent Current <5 mA One Input PWM Signal Generates Both Drive Bootstrapped High-Side Drive Operates from 4.5- to 30-V Supply TTL/CMOS Compatible Input Levels 1-A Peak Drive Current Break-Before-Make Circuit D D D D D Multiphase Desktop CPU Supplies Single-Supply Synchronous Buck Converters Mobile Computing CPU Core Power Converters Standard-Synchronous Converters High Frequency Switching Converters DESCRIPTION The Si9912 is a dual MOSFET high-speed driver with break-before-make. It is designed to operate in high frequency dc-dc switchmode power supplies. The high-side driver is bootstrapped to handle the high voltage slew rate associated with “floating” high-side gate drivers. Each driver is capable of switching a 3000-pF load with 60-ns propogation delay and 25-ns transition time. The Si9912 comes with an internal break-before-make feature to prevent shoot-through current in the external MOSFETs. A shutdown pin is used to enable the driver. When disabled, the quiescent current of the driver is less than 5 mA. The Si9912 is available in both standard and lead (Pb)-free, 8-pin SOIC packages for operation over the industrial operation range (−40_C to 85_C). FUNCTIONAL BLOCK DIAGRAM AND TRUTH TABLE BOOT VDD D1 VDC Q1 Level Shift TRUTH TABLE CBOOT OUTH VS SD Undervoltage OUTPUT VS VDD SD OUTL IN Q2 IN VOUTL VOUTH L L L L L L L H L L L H L H L L H H L H H L L L L H L H L L H H L L L H H H L H + − Document Number: 71311 S-40134—Rev. B, 16-Feb-04 VBBM GND www.vishay.com 1 Si9912 Vishay Siliconix ABSOLUTE MAXIMUM RATINGS (TA = 25_C UNLESS OTHERWISE NOTED) Parameter Symbol Limit VDD 7.0 Input Voltage on IN VIN −0.3 to VDD +0.3 Shutdown Pin Voltage VSD −0.3 to VDD +0.3 VBOOT 35.0 Low Side Driver Supply Voltage Bootstrap Voltage High Side Driver (Bootstrap) Supply Voltage Unit V VBOOT − VS 7.0 Operating Junction Temperature Range TJ −40 to 125 Storage Temperature Range Tstg −40 to 150 Power Dissipation (Note a and b) PD 830 mW Thermal Impedance qJA 125 °C/W 300 °C Lead Temperature (soldering 10 Sec) _C Notes a. Device mounted with all leads soldered to P.C. Board b. Derate 8.3 W/_C above 25_C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS Parameter Bootstrap Voltage (High-Side Drain Voltage) Logic Supply Bootstrap Capacitor Ambient Temperature Symbol Limit Unit VBOOT 4.5 to 30 VDD 4.5 to 5.5 CBOOT 100 n to 1 m F TA −40 to 85 _C V SPECIFICATIONS Test Conditions Unless Specified Parameter Symbol VDD = 4.5 to 5.5 V VBOOT = 4.5 to 30 V, TA = −40 to 85_C Limits Mina Typb Maxa Unit Power Supplies VDD Supply VDD IDD Supply IDD1(en) SD = H, IN = H, VS = 0 V 1000 IDD Supply IDD2(en) SD = H, IN = L, VS = 0 V 500 IDD Supply IDD3(dis) SD = L, IN = X, VS = 0 V 5 IDD Supply IDD4(en) SD = H, IN = X, VS = 25 V, VBOOT = 30 V 200 IDD Supply IDD5(dis) SD = L, IN = X, VS = 25 V, VBOOT = 30 V IDD(en) FIN = 300 kHz, SD = High, Driving Si4412DY 9 mA IDD(dis) FIN = 300 kHz, SD = Low, Driving Si4412DY 3 mA IBOOT VBOOT = 30 V, VS = 25 V, VOUTH = High IDD Supply Boot Strap Current 4.5 mA 5 0.9 3 mA VBBM 1.1 3 V Input High VIH 0.7 VDD VDD + 0.3 Input Low VIL −0.3 0.3 VDD Reference Voltage Break-Before-Make Reference Voltage Logic Inputs (SD, IN) V Undervoltage Lockout VDD Undervoltage VDD Undervoltage Hysteresis www.vishay.com 2 VUVL VHYST VDD Rising 3.7 4.3 0.4 V Document Number: 71311 S-40134—Rev. B, 16-Feb-04 Si9912 Vishay Siliconix SPECIFICATIONS Test Conditions Unless Specified Parameter Symbol VDD = 4.5 to 5.5 V VBOOT = 4.5 to 30 V, TA = −40 to 85_C VFD1 Forward Current = 100 mA Limits Mina Typb Maxa Unit 0.8 1 V Bootstrap Diode Diode Forward Voltage Output Drive Current OUTH Source Current IOUT(H+) VBOOT − VS = 3.7 V, VOUTH − VS = 2 V OUTH Sink Current IOUT(H−) VBOOT − VS = 3.7 V, VOUTH − VS = 1 V OUTL Source Current IOUT(L+) VDD = 4.5 V, VOUTL = 2 V OUTL Sink Current IOUT(L−) VDD = 4.5 V, VOUTL = 1 V −0.4 0.4 −0.4 A 0.6 Timing (CLOAD = 3 nF) OUTL Off Propagation Delay tpdl(OUTL) OUTL On Propagation Delay tpdh(OUTL) OUTH Off Propagation Delay tpdl(OUTH) OUTH On Propagation Delay tpdh(OUTH) OUTL Turn On Time 30 VDD = 4.5 45V 20 30 VBOOT − VS = 4.5 45V tr(OUTL) 20 OUTL = 10 to 90% 25 OUTL Turn Off Time tf(OUTL) OUTL = 90 to 10% 25 OUTH Turn On Time tr(OUTH) OUTH − VS = 10 to 90% 30 OUTH Turn Off Time tf(OUTH) OUTH − VS = 90 to 10% 20 ns Notes a. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum, is used in this data sheet. b. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. TIMING WAVEFORMS IN 50% 50% tpdh(OUTL) tf(OUTL) 90% OUTL 90% 10% 10% tr(OUTL) tpdl(OUTH) tpdl(OUTL) OUTH tf(OUTH) tr(OUTH) tpdh(OUTH) 90% 10% 90% 10% VS Document Number: 71311 S-40134—Rev. B, 16-Feb-04 www.vishay.com 3 Si9912 Vishay Siliconix PIN CONFIGURATION SO-8 OUTH 1 8 VS GND 2 7 BOOT IN 3 6 VDD SD 4 5 OUTL Top View PIN DESCRIPTION Pin Number Name Function 1 OUTH Output drive for upper MOSFET. 2 GND Ground supply 3 IN CMOS level input signal. Controls both output drives. 4 SD Shutdown pin 5 OUTL 6 VDD 7 BOOT 8 VS Output drive for lower MOSFET. Input power supply Floating bootstrap supply for the upper MOSFET Floating GND for the upper MOSFET. VS is connected to the buck switching node and the source side of the upper MOSFET. ORDERING INFORMATION Part Number Temperature Range Si9912DY Si9912DY-T1 Package Bulk −40 to 85_C Si9912DY-T1—E3 (Lead (Pb)-Free) Tape and Reel Eval Kit Temperature Range Board Type Si9912DB −40 to 85_C Surface Mount TYPICAL WAVEFORMS Driver On Switch Delay VS CL = Si4412DY Driver Off Switch Delay OUTH OUTH See Figure 1 OUTL IN IN Si9912 tr, tf, tpd 4 See Figure 1 OUTL www.vishay.com CL = Si4412DY VS Si9912 tr, tf, tpd Document Number: 71311 S-40134—Rev. B, 16-Feb-04 Si9912 Vishay Siliconix TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) IDD Supply Current vs. Frequency Rise and Fall Time vs. CLOAD 30 50 See Figure 2 40 Rise and Fall times (ns) See Figure 1 Current (mA) 10 tr(OUTH) tf(OUTL) 30 tf(OUTH) 20 tr(OUTL) 10 1 0 1 10 100 1000 0.3 1 Frequency (kHz) VOUT(H+) vs. Supply 5 See Figure 3 0.5 A 4 Output Voltage Drop (V) Output Voltage Drop (V) −1 −2 1A −3 1.5 A −5 3.0 3 1.5 A 2 1A 1 See Figure 3 3.5 2A 4.0 4.5 5.0 5.5 0 3.0 6.0 0.5 A 3.5 4.0 Supply Voltage (V) 0.5 A 6.0 See Figure 3 2.0 1A 1.5 A −3 −4 2A −6 4.0 5.5 VOUT(L−) vs. Supply −2 −5 5.0 2.5 Output Voltage Drop (V) Output Voltage Drop (V) −1 4.5 Supply Voltage (V) VOUT(L+) vs. Supply 0 10 VOUT(H−) vs. Supply 0 −4 3 Load Capacitance (nF) 5.0 Supply Voltage (V) Document Number: 71311 S-40134—Rev. B, 16-Feb-04 1.5 A 1.0 1A 0.5 See Figure 3 4.5 2A 1.5 5.5 6.0 0.0 4.0 0.5 A 4.5 5.0 5.5 6.0 Supply Voltage (V) www.vishay.com 5 Si9912 Vishay Siliconix TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) VOUT(H+) vs. Temperature VOUT(H−) vs. Temperature 0 5 See Figure 3 0.5 A −2 4 Output Voltage Drop (V) Output Voltage Drop (V) −1 1A −3 See Figure 3 −4 −5 −50 3 2A 1.5 A 2 1A 1 −25 0 25 50 75 0 −50 100 0.5 A −25 0 Temperature (_C) VOUT(L+) vs. Temperature 0 −1 75 100 75 100 VOUT(L−) vs. Temperature See Figure 3 1A Output Voltage Drop (V) Output Voltage Drop (V) 50 2.0 0.5 A −2 1.5 A −3 −4 1.5 1.0 2A 1.5 A 1A 0.5 0.5 A 2A −5 −50 25 Temperature (_C) −25 0 See Figure 3 25 50 75 100 Temperature (_C) 0.0 −50 −25 0 25 50 Temperature (_C) THEORY OF OPERATION Break-Before-Make Function Under Voltage Lockout Function The Si9912 has an internal break-before-make function to ensure that both high-side and low-side MOSFETs are not turned on at the same time. The high-side drive (OUTH) will not turn on until the low-side gate drive voltage (measured at the OUTL pin) is less than VBBM, thus ensuring that the low-side MOSFET is turned off. The low-side drive (OUTL) will not turn on until the voltage at the MOSFET half-bridge output (measured at the VS pin) is less than VBBM, thus ensuring that the high-side MOSFET is turned off. The Si9912 has an internal under-voltage lockout feature to prevent driving the MOSFET gates when the supply voltage (at VDD) is less than the under-voltage lockout specification (VUVL). This prevents the output MOSFETs from being turned on without sufficient gate voltage to ensure they are fully on. There is hysteresis included in this feature to prevent lockout from cycling on and off. www.vishay.com 6 Document Number: 71311 S-40134—Rev. B, 16-Feb-04 Si9912 Vishay Siliconix Bootstrap Supply Operation (see Functional Block Diagram) Layout Considerations There are a few critical layout considerations for these parts. Firstly, the IC must be decoupled as closely as possible to the power pins. Secondly the IC should be placed physically close to the high- and low-side MOSFETs it is driving. The major consideration is that the MOSFET gates must be charged or discharged in a few nanoseconds, and the peak current to do this is of the order of 1 A. This current must flow from the decoupling and bootstrap capacitors to the IC, and from the output driver pin to the MOSFET gate, returning from the MOSFET source to the IC. The aim of the layout is to reduce the parasitic inductance of these current paths as much as possible. This is accomplished by making these traces as short as possible, and also running trace and its current return path adjacent to each other. The power to drive the high-side MOSFET (Q2) gate comes from the bootstrap capacitor (CBOOT). This capacitor charges through D1 during the time when the low-side MOSFET is on (VS is at GND potential), and then provides the necessary charge to turn on the high-side MOSFET. CBOOT should be sized to be greater than ten times the high-side MOSFET gate capacitance, and large enough to supply the bootstrap current (IBOOT) during the high-side on time, without significant voltage droop. Shutdown (SD) (shutdown input, active low) When this pin is high, the IC operates normally. When this pin is low, both high- and low-side MOSFETs are turned off . APPLICATIONS 5 6 7 8 +VDC Q1 4 Enable 3 4 OUTH GND VS BOOT IN SD VDD OUTL 7 6 L1 1 2 3 8 C1 0.1 mF 15 mH 5 6 7 8 PWM IN Si4412 5 C2 0.1 mF GND 1 mF C5 RLOAD Q2 4 Si9912 Si4412 1 2 3 2 15 mF C4 + +5 V U1 1 0.1 mF C3 GND GND FIGURE 1. Document Number: 71311 S-40134—Rev. B, 16-Feb-04 Typical Applications Schematic Circuit Used to Obtain Typical Rising and Falling Switching Waveforms www.vishay.com 7 Si9912 Vishay Siliconix +5 V +5 V U1 U1 1 2 PWM IN 3 4 OUTH GND VS BOOT IN SD VDD OUTL Si9912 8 7 1 CLOAD C9 6 2 3 Input 4 5 CLOAD C8 FIGURE 2. Capacitive Load Test Circuit Used to Measure Rise and Fall Times vs. Capacitance www.vishay.com 8 GND BOOT VDD IN SD OUTL Si9912 8 ISRC 7 6 5 ISRC C2 0.1 mF C2 0.1 mF GND VS OUTH GND FIGURE 3. Load Test Schematic Circuit Used to Measure Driver Output Impedance Document Number: 71311 S-40134—Rev. B, 16-Feb-04