DEMO MANUAL DC102 50V N-CHANNEL HALF BRIDGE LT1336 Half-Bridge N-Channel Power MOSFET Driver with Boost/Flyback Regulator U DESCRIPTIO This demonstration circuit is an N-channel half-bridge for general purpose applications. The half-bridge can be driven with TTL/CMOS level signals into an LT ® 1336, which drives the N-channel MOSFETs. A self-contained highside driver regulator allows PWM operation to 100% duty cycle without discontinuities. By adding a controller IC and WW U W PERFORMANCE SUMM ARY SYMBOL PARAMETER VIN LT1336 Input Voltage Range some other components in the space provided for prototyping, this demo board can be turned into a complete system solution. The half-bridge consists of four power MOSFETs, two paralleled topside MOSFETs and two paralleled bottom side MOSFETs. , LTC and LT are registered trademarks of Linear Technology Corporation. Operating Temperature Range 0°C to 50°C, VIN = 12V unless otherwise noted. CONDITION VALUE 10V to 15V IQ LT1336 Typical Supply Current HV High Voltage Range INTOP = INBOTTOM = 0V 15mA RDS(ON) Power MOSFETs RDS(ON) VGS = 10V 0.09Ω ESR ESR of Bypass Capacitor 100kHz 0.03Ω IPK Max Ripple Current PIN Max Power Input fMAX Max Operating Frequency 0V to 50V (60V Abs Max) 4.5A (Note 1) 150W 100kHz Note 1: For applications requiring higher input power, attach heat sinks to all power MOSFETs. BOARD PHOTOS Demo Board with a Flyback High-Side Driver Regulator Demo Board with a Boost High-Side Driver Regulator 1 DEMO MANUAL DC102 50V N-CHANNEL HALF BRIDGE W W U PACKAGE AND SCHEMATIC DIAGRAMS TOP VIEW D2 1N4148 E3 VIN 10V TO 15V SV R2,2Ω 1/4W, 5% + C1 10µF 25V R1 24k 1/4W 5% C11 0.1µF 50V + SWGND BOOST INTOP T1* D1 1N4148 R7 6.2k 1/4W D3 5% 1N4148 C9 1000pF 25V SW ISENSE INBOTTOM TGATEDR UVOUT TGATEFB SGND TSOURCE PGND PV + BGATEDR BGATEFB E4 UVOUT 1 I SENSE 2 SV+ 3 INTOP E5 INTOP E6 INBOTTOM 4 5 6 7 8 N PACKAGE 16-LEAD PDIP SW 16 15 SWGND BOOST 14 INBOTTOM U1 LT1336 UVOUT TGATEDR TGATEFB SGND TSOURCE PGND PV+ BGATEFB BGATEDR LT1336CN E1 HV 0V TO 50V 13 C2 1µF 25V 12 R3 10Ω 1/4W 5% 11 10 R4 10Ω 1/4W 5% + Q2 MTP50N06V Q1 MTP50N06V C3 TO C8 330µF 63V ×6 E2 OUT 9 D5 1N5819 E7 GND R5 10Ω 1/4W 5% R6 10Ω 1/4W 5% Q3 MTP50N06V Q4 MTP50N06V *T1 = CTX100-1P BOLD LINES INDICATE HIGH CURRENT PATHS FOR BOOST TOPOLOGY REPLACE COMPONENTS IN DASHED AREA WITH THE INDUCTOR AS SHOWN IN FIGURE 2 DM102A • F01 Figure 1. Demonstration Circuit with a Flyback HIgh-Side Driver Regulator D2 1N4148 L1 REPLACES THE DASHED COMPONENTS IN FIGURE 1 C1 10µF 25V + R2 2Ω 1/4W 5% E3 VIN 10V TO 15V E5 INTOP E6 INBOTTOM E4 UVOUT L1* 200µH 1 I SENSE 2 SV+ 3 INTOP 4 R1, 24k 1/4W, 5% 13 INBOTTOM TGATEDR U1 LT1336 5 12 UVOUT TGATEFB 6 7 8 SGND TSOURCE PGND PV+ BGATEFB D1 1N4148 SW 16 15 SWGND BOOST 14 BGATEDR + C2 1µF 25V 11 10 R4 10Ω 1/4W 5% Q1 MTP50N06V R5 10Ω 1/4W 5% R6, 10Ω 1/4W 5% Q3 MTP50N06V BOLD LINES INDICATE HIGH CURRENT PATHS * SUMIDA RCH-664D-221 KC Figure 2. Demonstration Circuit with a Boost High-Side Driver Regulator 2 + Q2 MTP50N06V C3 TO C8 330µF 63V ×6 E2 OUT 9 D5 1N5819 E7 GND R3 10Ω 1/4W 5% E1 HV 0V TO 40V Q4 MTP50N06V DM102A • F02 DEMO MANUAL DC102 50V N-CHANNEL HALF BRIDGE PARTS LIST REFERENCE DESIGNATOR PART NUMBER DESCRIPTION VENDOR C1 QUANTITY 1 25SC10M 10µF 25V 20% Electrolytic Capacitor Sanyo (619) 661-6835 TELEPHONE C2 1 25SC1M 1µF 25V 20% Electrolytic Capacitor Sanyo (619) 661-6835 C3 to C8 6 63MV330CZ 330µF 63V Aluminum Capacitor Sanyo (619) 661-6835 C9 1 FKC02 1000pF 25V 10% Mylar Capacitor WIMA (914) 347-2474 C10 1 25SC10M Option Capacitor Sanyo (619) 661-6835 C11 1 MKS2 0.1µF 63V 5% Mylar Capacitor WIMA (914) 347-2474 D1 to D3 3 1N4148 Diode Philips (800) 774-4547 D5 1 1N5819 Diode Motorola (602) 244-3576 L1 1 RCR-664D-221KC 0.99Ω 0.30A Inductor (Optional) Sumida (847) 956-0666 Q1 to Q4 4 MTP50N06V 50A 60V TO-220 MOSFET Motorola (602) 244-3576 R1 to R7 7 1/4W 5% Resistor Any T1 1 CTX100-1P Transformer Coiltronics (407) 241-7876 U1 1 LT1336 IC LTC (408) 432-1900 QUICK START GUIDE Demonstration board 102 is easily set up for evaluation of the LT1336 IC. Please follow the procedure below for error-free operation. • Connect the positive lead of a low power supply to VIN (E3) and the negative lead to GND (E7). The voltage range of this supply must be between 10V – 15V. • Connect the positive lead of a high power supply to HV (E1) and the negative lead to GND (E7). The recommended maximum operating voltage is 50V. The capacitors, the MOSFETs and the IC are rated at 60V absolute maximum. • Connect the driving signals into INTOP (E5) and INBOTTOM (E6). Taking INTOP high and INBOTTOM low turns the top MOSFETs on and the bottom MOSFETs off. Taking INTOP low and INBOTTOM high reverses these states. When both inputs are either high or low, all the MOSFETs are off. These inputs are TTL/CMOS compatible and can withstand input voltages as high as VIN. • Connect the load between OUT (E2) and GND (E7). U OPERATION A general purpose half-bridge is implemented using the LT1336. Figure 1 is the schematic for this demonstration board. The half-bridge can be used as a building block for a number of different applications, including synchronous switching regulators, motor control and class-D amplifiers. By adding the appropriate controller IC in the prototyping space, a complete system solution can be created. This demonstration unit is intended for the evaluation of the LT1336 half-bridge driver and was not designed for any other purpose. To power this demo board, connect a low power 10V to 15V supply to VIN (E3) and a high power supply, up to 50V to HV (E1). To evaluate the LT1336 driving the half-bridge, connect two complementary signals from a function 3 DEMO MANUAL DC102 50V N-CHANNEL HALF BRIDGE U OPERATION generator to INTOP (E5) and INBOTTOM (E6). These inputs to the LT1336 are TTL/CMOS compatible and can withstand input voltages as high as VIN. Both driver channels are noninverting. The internal logic of the LT1336 prevents the top MOSFETs and bottom MOSFETs from turning on simultaneously under any input conditions. For instance, when both inputs are high both outputs are actively held low. The LT1336 incorporates a small switching regulator to charge the floating high-side driver supply above the high voltage rail. This regulator can provide enough charge to the floating supply capacitor to allow the top driver to drive several power MOSFETs in parallel at 100kHz, its maxi- mum operating frequency. The regulator voltage across VBOOST – VTSOURCE is 10.6V. Unlike bootstrapping techniques with internal charge pumps, the built-in regulator enables the half-bridge to operate from PWM to DC without discontinuities. In conventional half-bridge drivers using bootstrapping techniques and internal charge pumps, approaching DC may cause some serious problems. When the duty cycle approaches 100%, the output pulse width becomes too narrow for the floating capacitor to recharge. This capacitor is being continuously depleted by the gate charging currents of the top MOSFETs. The internal charge pump is too weak to provide the currents needed to replenish the Functional Diagram for the LT1336 V+ ISENSE + 1 16 SW – 15 SWGND 14 BOOST 6V 480mV TRIP = 10.6V TRIP = 8.7V V+ 2 TOP UV DETECT BIAS 13 TGATEDR – 3k 3 12 TGATEFB + INTOP 5V 2.9V 11 T SOURCE 10 PV + 3k INBOTTOM 4 5V BOTTOM UV LOCK 5 SGND 6 PGND 7 BGATEFB 8 – UVOUT 9 + 2.5V DC102 FD 4 BGATEDR DEMO MANUAL DC102 50V N-CHANNEL HALF BRIDGE U OPERATION floating capacitor. Thus, at a point between 90% and 100% duty cycles, the floating capacitor will be depleted, causing a discontinuity and potential overdissipation of the top MOSFETs. In this demo board the built-in switching regulator of the LT1336 comes configured as a flyback regulator, as shown in Figure 1. To configure a flyback regulator, a resistor, a diode, a small 1:1 turns ratio transformer and a capacitor are needed. The maximum voltage across the switch, assuming an ideal transformer, will be about VIN + 11.3V. Leakage inductance in nonideal transformers will induce an overvoltage spike at the switch the instant that it opens. These spikes are clamped using the snubbing network D3, C9 and R7. Using the components as shown in Figure 1, the flyback regulator will run at around 800kHz. To lower the frequency, increase the value of C11; to raise the frequency, decrease the value of C11. The flyback regulator works as follows: when the switch is on, the primary current ramps up as the magnetic field builds up. The magnetic field in the core induces a voltage on the secondary winding equal to VIN. However, no power is transferred to VBOOST because the rectifier diode D1 is reverse biased. The energy is stored in the transformer’s magnetic field. When the primary inductor peak current is reached, the switch is turned off. Energy is no longer transferred to the transformer, causing the magnetic field to collapse. The collapsing magnetic field induces a change in voltage across the transformer’s windings. During this transition the Switch pin’s voltage flies to 10.6V plus a diode above VIN, the secondary forward biases the rectifier diode D1 and the transformer’s energy is transferred to VBOOST. Meanwhile, the primary inductor current goes to zero and the voltage at ISENSE decays to the lower inductor current threshold with a time constant of (R2)(C11), thus completing the cycle. Using the flyback regulator allows the maximum voltage (50V) to be applied at the high voltage rail, HV. In applica- tions where the high voltage rail does not exceed 40V, the boost topology can be used. The advantage, as shown in Figure 2, is simplicity . Only a resistor, a small inductor, a diode and a capacitor are needed; there is no need for a snubber circuit. The current drawn from VIN will be higher, however, by a factor of VBOOST/VIN. To reconfigure the demo board’s flyback regulator into a boost regulator, remove the snubber circuit’s components, C9, R7, D3 and the transformer T1. Reconnect diode D1 and insert the optional inductor as shown in the Board Photos. Using the components provided with the demo board (2Ω sense resistor, 200µH inductor and 1µF capacitor) the boost regulator will run at around 700kHz. To lower the frequency increase the inductor value; to increase the frequency decrease the inductor value. The boost regulator works as follows: when the switch is on, the inductor current ramps up as the magnetic field builds up. During this interval energy is being stored in the inductor and no power is transferred to VBOOST. When the 2Ω resistor senses that the peak inductor current has been reached, the switch is turned off. Energy is no longer transferred to the inductor, causing the magnetic field to collapse. The collapsing magnetic field induces a change in voltage across the inductor. The Switch pin’s voltage rises until diode D1 starts conducting. As the inductor current ramps down, the lower inductor current threshold is reached and the switch is turned on, starting the next cycle. Current drawn from VIN is delivered to VBOOST. Some of this current (~1.5mA) flows through the topside driver to E2. This current is typically returned to ground via the bottom MOSFETs or the output load. If the bottom MOSFETs are off and the output load is returned to HV, E2 will return the current to HV through the top MOSFET or the output load. If the HV supply cannot sink current and no load drawing greater than 1.5mA is connected to the supply, a resistor from HV to ground may be needed to prevent voltage buildup on the HV supply. 5 DEMO MANUAL DC102 50V N-CHANNEL HALF BRIDGE W U PC LAYOUT AND FILM 6 Component Side Silkscreen Component Side Component Side Pastemask Component Side Solder Mask DEMO MANUAL DC102 50V N-CHANNEL HALF BRIDGE W U PC LAYOUT AND FILM Solder Side Solder Side Soldermask Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7 DEMO MANUAL DC102 50V N-CHANNEL HALF BRIDGE U PC FAB DRAWING 4.975 H B B C C C C C C C C C C C C E D C E D E E E C C A G E E E E F E E E E E 3.975 E E D D C C D D C C D G E D A G C C E E G E E E F A A F D D D D B B E E NOTES: 1. MATERIAL: FR4 OR EQUIVALENT EPOXY, 2 OZ COPPER CLAD THICKNESS 0.062 ±0.006 TOTAL OF 2 LAYERS 2. FINISH: ALL PLATED HOLES 0.001 MIN/0.0015 MAX COPPER PLATE ELECTRODEPOSITED TIN-LEAD COMPOSTION BEFORE REFLOW, SOLDER MASK OVER BARE COPPER (SMOBC) 3. SOLDER MASK: BOTH SIDES USING GREEN PC-401 OR EQUIVALENT 4. SILKSCREEN: USING WHITE NONCONDUCTIVE EPOXY INK 5. ALL DIMENSIONS ARE IN INCHES 8 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 ● (408) 432-1900 FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com H DM102A • PC FAB DWG SYMBOL DIAMETER NUMBER OF HOLES A 0.095 4 B 0.125 4 C 0.028 21 D 0.032 180 E 0.040 24 F 0.205 3 G 0.156 4 H 0.072 2 TOTAL HOLES 242 LT/GP 0197 500 • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1997