High Speed Synchronous MOSFET Driver Advanced Digital Timing Filt

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High Speed Synchronous MOSFET Driver Advanced Digital Timing Filt

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SC1218 high speed, robust, dual output driver drive high-side low-side N-MOSFETs synchronous buck converters. Combined with Semtech's multi-phase controller SC2649, build high performance, versatile voltage regulators next generation microprocessors. SC1218 built upon CMOS technology which provides enough voltage capacity handle computer applications. addition, advanced timing circuitry adopted filter very narrow pulses input driver. latched UVLO enhanced adaptive shoot-through protection further enhance robustness SC1218. With integrated bootstrap diode, SC1218 offered both SOIC-8 package MLPQ-8 3x3mm package. These features further reduce thermal stress cost.
High Speed Synchronous MOSFET Driver
Advanced Digital Timing Filter Very Narrow Pulses +12V Gate Drive Voltage Integrated Bootstrap Diode High Peak Drive Current Adaptive Non-overlapping Gate Drives Provide Shootthrough Protection Support Dynamic operation Ultra-low Propagation Delay Floating Gate Drive Crowbar Function Over Voltage Protection High Frequency MHz) Operation Allows Small Inductors Cost Ceramic Capacitors Under Voltage Lockout Quiescent Current Enable Function Both Gate Shut Down Lead-free Part Fully WEEE RoHS Compliant
SC1218
Applications
Intel Next Generation Processor Power Supplies Athlonand AMD-K8Processor Power
Supplies
High Current Voltage DC-DC Converters
Typical Application Circuit
Cbst PGND
Mtop
Rdrn (optional) Mbot
Lout
VOUT
SC1218
Cout
Revision: October 2005
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SC1218
POWER MANAGEMENT Absolute Maximum Ratings
Exceeding specifications below result permanent damage device, device malfunction. Operation outside parameters specified Electrical Characteristics section implied.
Parameter Supply Voltage Pulse PGND PGND Pulse PGND PGND Pulse PGND PGND Pulse Input Enable Input Continuous Dissipation TA=25oC, TJ=125oC Thermal Resistance Junction Case Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering) Sec.
Symbol VBST-DRN VBST-VIN VTG-DRN VTG-DRN-PULSE VBST-PGND VBST-PGND-PULSE VDRN-PGND VDRN-PGND-PULSE VBG-PGND VBG-PGND-PULSE
Conditions
Maximum -0.3 -0.3 -0.3 -0.3
Units
VPEAK tPULSE 20ns(1)
-0.3 VIN+16
tPULSE <20ns VBST-VDRN VPEAK tPULSE 200ns(1) VPEAK tPULSE 20ns(1)
VIN+16 -0.3 VIN+0.3
VPEAK tPULSE 20ns(1)
-3.5 -0.3 VIN+0.3 -0.3 VIN+0.3
SOIC-8 MLPQ-8 SOIC-8 MLPQ-8
2.56
TSTG TLEAD
SOIC-8 MLPQ-8
Notes: Pulse width measured triangular spike waveform. This device sensitive. standard handling precautions required.
Electrical Characteristics
Unless specified: 25°C; 12V.
Parameter Power Supply Supply Voltage
Symbol
Conditions
Units
EN=5V; CO=0V
3.35 1.35
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Quiescent Current
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EN=5V; CO=5V EN=0V
SC1218
POWER MANAGEMENT Electrical Characteristics (Cont.)
Unless specified: 25°C; 12V.
Parameter Under Voltage Lockout Start Threshold Voltage Hysteresis Logic High Input Voltage Logic Input Voltage Logic High Input Voltage Logic Input Voltage Internal Pull-down Resistor High Side Driver (TG) Output Impedence
Symbol
Conditions
Units
VIN_START VhysUVLO
VEN_H VEN_L
2.65
VCO_H VCO_L
Kohm
RSRC_TG RSINK_TG ISRC_TG_PK ISINK_TG_PK tPDH_TG tPDL_TG tON_MIN_TG
VBST-VDRN= VIN=12V, CTG=10nF VIN=12V, CTG=10nF VBST-VDRN= VBST-VDRN= pulse width 40ns
1.68 0.52
0.78
Output Peak Current Propagation Delay, Going High Propagation Delay, Going Minimum On-time(1) Side Driver (BG) Output Impedence
RSRC_BG RSINK_BG ISRC_BG_PK ISINK_BG_PK tPDH_BG tPDL_BG tOFF_MIN_BG tDH_MAX_BG
VIN=12V, CBG=10nF VIN=12V, CBG=10nF pulse width 40ns From CO=Low, VDRN>1V
1.36 0.52
0.78
Output Peak Current Propagation Delay, Going High Propagation Delay, Going Minimum OFF-time(1) Maximum Turn Delay(1)
NOTE: (1). Guaranteed design.
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SC1218
POWER MANAGEMENT Timing Diagrams
VCO_HI
VCO_LO
tPDH_TG tPDL_BG
VIN>UVLO EN="HI"
tPDL_TG
1.4V
tPDH_BG
1.0V
Rising Edge Transition
Falling Edge Transition
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SC1218
POWER MANAGEMENT Configuration
SOIC-8 View MLPQ-8 3x3mm View
PGND
PGND
EXPOSED MUST SOLDERED POWER GROUND PLANE
Descriptions
SOIC-8 LPQ-8 Name PGND Function Bootstrap supply gate drive. Connect ceramic capacitor between develop floating bootstrap voltage high side driver. input signal from external controller. internal 40Kohm resistor connected from this PGND. When high, this enables internal circuitry device. When low, forced low. Supply power bottom gate driver internal control circuitry. Connect input power rail converter dcouple with ceramic with lead length more than 0.2" (5mm). Output gate drive bottom (synchronous) MOSFET. internal 20Kohm resistor connected from this PGND. Supply power ground return. Keep this close bottom MOSFET source during layout. Connect this power phase node synchronous buck converter (source MOSFET drain bottom MOSFET). provides return path gate drive. voltage deteced adaptive shoot-through protection. This subjected negative spike relative PGND without affecting operation. internal 20Kohm resistor connected from this PGND. Output gate drive (switching) MOSFET.
Ordering Information
Device SC1218STRT (1)(3) SC1218MLTRT (2)(3) Package SOIC-8 MLPQ-8 Temp Range (TJ) 150°C 150°C
Note: Only available tape reel packaging. reel contains 2500 devices. Only available tape reel packaging. reel contains 3000 devices. Devices lead-free fully WEEE RoHS compliant.
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SC1218
POWER MANAGEMENT Block Diagram
UVLO
CONTROL OVERLAP PROTECTION CIRCUIT
PGND
Typical Performance Characteristics
Fig. Rise Fall Times
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Fig. Fall Rise Times
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SC1218
POWER MANAGEMENT Typical Performance Characteristics (Cont.)
VIN=12V CLoad=3.3nF
VIN=12V TA=25°C
FALL TIME (ns)
RISE TIME (ns)
TEMPERATURE (°C)
LOAD CAPACITANCE (nF)
Fig. Rise Times Temperature.
Fig. Fall Times Load Capacitance.
VIN=12V CLoad=3.3nF
SUPPLY CURRENT (mA)
VIN=12V CLoad_TG=3.3nF CLoad_BG=3.3nF TA=25°C
FALL TIME (ns)
TEMPERATURE (°C)
1000 1200 1400 1600 FREQUENCY (KHz)
Fig. Fall Times Temperature.
Fig. Supply Current Frequency.
VIN=12V TA=25°C
SUPPLY CURRENT (mA)
VIN=12V CLoad_TG=3.3nF CLoad_BG=3.3nF Freq.=200KHz
RISE TIME (ns)
LOAD CAPACITANCE (nF)
TEMPERATURE (°C)
Fig. Rise Times Load Capacitance.
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Fig. Supply Current Temperature.
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SC1218
POWER MANAGEMENT Typical Performance Characteristics (Cont.)
ISRC_PK ISINK_PK CLOAD_TG=10nF CLOAD_BG=10nF TA=25°C LOAD_TG=10nF LOAD_BG=10nF TA=25°C
Fig. Peak Sourcing Current Supply Voltage.
Fig. Peak Sinking Current Supply Voltage.
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SC1218
POWER MANAGEMENT Applications Information
THEORY OPERATION THEORY OPERATION SC1218 high speed, robust, dual output driver designed drive bottom MOSFETs synchronous Buck converter. features internal bootstrap diode, adaptive delay shoot-through protection, gate drive voltage, disable shutdown. also supports dynamic operation CROWBAR function. This driver combined with controller SC2649 forms multi-phase voltage regulator advanced microprocessors. Startup UVLO Star UVLO startup driver, supply voltage applied SC1218. bottom gates held until exceeds UVLO threshold driver, typically 4.0V. UVLO threshold hysteresis, typically -250mV, improve nosie immunity from pin. Gate Transition Shoot-thr t-through Gate Transition Shoo t-through ection Refer Timing Diagrams section, rising edge input initiates turn-off bottom turn-on FET. After short propagation delay (tPDL_BG) from rising edge, bottom gate falls (tF_BG). adaptive circuit SC1218 detects bottom gate voltage. holds gate until bottom gate voltage drops below 1.4V preset delay time (tPDH_TG). This prevents from turning until bottom off. During transition, inductor current freewheeling through body diode either bottom FET, depended direction inductor current. phase node could (ground) high (VIN). falling edge input controls turn-off turn-on bottom FET. After short propagation delay (tPDL_TG) from falling edge, gate falls (tF_TG). inductor current commutates from body diode bottom FET, phase node falls. adaptive circuit SC1218 detects phase node voltage. holds bottom until phase node voltage drops below 1.0V. This prevents bottom FETs from conducting simultaneously (shoot-through). phase node voltage remains high during transition preset maximum turn delay (tDH_MAX_BG) then bottom gate will turned This supports CROWBAR function sinking current capacity required from dynamic operation. Narrow Pulse Filtering During load transient, soft start, soft shutdown voltage regulator, controller generate very
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narrow pulse driver. pulse narrow that reaches rising edge threshold SC1218 point then immediately falls below falling edge threshold. prevent SC1218 from reacting such narrow pulses, which cause driver output ringing shoot through, advanced timing circuitry added ease gate transitions. minimum off-time (typically 140ns) bottom gate minimum on-time (typically 40ns) gate enforced make operation safe under such conditions. Dynamic Operation Some processors changes dynamically during operation (Dynamic operation). dynamic occur under light load heavy load conditions. light load, force converter sink current. After turn-off FET, reversed inductor current flows through body diode instead bottom FET. result, phase node voltage remains high voids adaptive circuit. SC1218 features maximum turn delay (tDH_MAX_BG) override adaptive delay turn bottom preset maximum turn delay time (tDH_MAX_BG) from falling egde bottom gate turn-on 175ns. Frequency, Inductor requency MOSFETs Switching Freq uency, Inductor MOSFETs SC1218 capable providing more than 3.5A peak drive current, operating 2MHz frequency without causing thermal stress driver. selection switching frequency, together with inductor FETs trade-off between cost, size, thermal management multi-phase voltage regulator. Typically, these parameters could range Switching Frequency: 100kHz 500kHz phase Inductor Value: 0.2uH MOSFETs: 4mOhm 20mOhm RDS(ON) 20nC 100nC total gate charge Bootstrap Chip Decoupling Capacitors gate driver SC1218 refered gate drive whose supply voltage derived from bootstrap circuit comprising capacitor,CBST, built-in diode. capacitor value calculated based total gate charge FET, QTOP, allowed voltage ripple capacitor, VBST, cycle:
QTOP VBST
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SC1218
POWER MANAGEMENT Applications Information (Cont.)
POWER DISSIPATION (mW)
Typically, 1uF/16V ceramic capacitor used. addition, small resistor (one ohm) recommended between SC1218 phase node. resistor used alleviate stress SC1218, resulting from negative spike phase node, also control switching speed. negative spike could occur phase node during turn-off parasitic inductance switching loop. spike could minimized with careful layout. applications with TO-220 package FETs, suggested clamping diode mitigate impact excessive phase node negative spikes. SC1218, recommended 1uF/16V ceramic capacitor decoupling. Driver Dissipation Junction Temperature Driver emperature driver power dissipation function chip quiescent current switching frequency FSW, supply voltage VIN. approximated
QTOTAL
typical layout examples SC1218 based above guidelines shown Fig.12 Fig.13.
1000 Fsw=600kHz
Fsw=400kHz
Fsw=200kHz
TOTAL GATE CHARGE (nC)
Fig. Power dissipation.
RDRN
where QTOTAL total gate charge top-side bottom-side FETs. power dissipation total gate charge given switching frequency plotted Fig.11. driver junction temperature calculated based juntion case thermal resistance Printed Circuit Board (PCB) temperature. LAYOUT GUIDELINES switching regulator high di/dt dv/dt power circuit. layout critical. good layout achieve optimum circuit performance with minimized component stress, resulting better system reliability. multiphase voltage regulator, SC1218 driver, FETs, inductor, supply decoupling capacitors each phase have considered unit. SC1218 driver, following guidelines typically recommended during layout: Place SC1218 close FETs shortest gate drive traces ground return paths; Connect decoupling capacitor close possible PGND pin. trace length capacitor should more than 0.2" (5mm); Locate bootstrap capacitor close SC1218.
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phase node
bottom
Fig. Component placement SOIC-8
CBST
RVIN
Phase Node
RDRN CVIN
Bottom
Fig. Component placement MLPQ-8.
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SC1218
POWER MANAGEMENT Outline Drawing SOIC-8
DIMENSIONS INCHES MILLIMETERS
.069 .053 .010 .004 .065 .049 .012 .020 .007 .010 .189 .193 .197 .150 .154 .157 .236 .050 .010 .020 .016 .028 .041 (.041) .004 .010 .008 1.35 1.75 0.25 0.10 1.65 1.25 0.31 0.51 0.25 0.17 4.80 4.90 5.00 3.80 3.90 4.00 6.00 1.27 0.25 0.50 0.40 0.72 1.04 (1.04) 0.10 0.25 0.20
TIPS SEATING PLANE
GAGE PLANE 0.25
DETAIL SIDE VIEW
NOTES:
(L1) DETAIL
CONTROLLING DIMENSIONS MILLIMETERS (ANGLES DEGREES).
DATUMS DETERMINED DATUM PLANE -H3. DIMENSIONS "E1" INCLUDE MOLD FLASH, PROTRUSIONS GATE BURRS. REFERENCE JEDEC MS-012, VARIATION
Land Pattern SOIC-8
NOTES:
DIMENSIONS INCHES MILLIMETERS
(.205) .118 .050 .024 .087 .291 (5.20) 3.00 1.27 0.60 2.20 7.40
THIS LAND PATTERN REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES MET. REFERENCE IPC-SM-782A, 300A.
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SC1218
POWER MANAGEMENT Outline Drawing MLPQ-8,
View
INDICATOR (LASER MARK)
DIMENSIONS INCHES MILLIMETERS
.032 .040 .000 .002 .008 .012 .007 .118 .071 .059 .071 .059 .118 .026 .012 .016 .020 .008 .003 .008 0.08 1.00 0.00 0.05 0.20 0.19 0.30 3.00 1.50 1.80 1.50 1.80 3.00 0.65 0.30 0.40 0.50 0.20 0.08 0.20
SEATING PLANE
Bottom View
Land Pattern MLPQ-8,
DIMENSIONS INCHES MILLIMETERS
(.122) .089 .073 .073 .026 .014 .033 .156 (3.10) 2.25 1.85 1.85 0.65 0.35 0.85 3.95
NOTES: THIS LAND PATTERN REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES MET. VIAS CENTER SHOULD MAINTAIN GOOD THERMAL CONTACT DEVICE GROUND PLANE.
Contact Information
Semtech Corporation Power Management Products Division Flynn Road, Camarillo, 93012 Phone: (805)498-2111 (805)498-3804
2005 Semtech Corp. www.semtech.com

High Speed Synchronous MOSFET Driver Advanced Digital Timing Filt

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