MAX15018AASA

19-4146; Rev 1; 9/08 125V/3A, High-Speed, Half-Bridge MOSFET Drivers General Description The MAX15018A/MAX15018B/MAX15019A/MAX15019B high-frequency, 125V half-bridge, n-channel MOSFET drivers drive high- and low-side MOSFETs in high-voltage applications. These drivers are independently controlled, and their 35ns (typ) propagation delay, from input to output, are matched to within 2ns (typ). The high-voltage operation with very low and matched propagation delay between drivers, and high source-/sink-current capabilities in a thermally enhanced package make these devices suitable for high-power, high-frequency telecom power converters. The 125V maximum input voltage provides plenty of margin over the 100V input transient requirement of telecom standards. A reliable on-chip bootstrap diode connected between VDD and BST eliminates the need for an external discrete diode. The MAX15018A/MAX15019A both offer noninverting drivers. The MAX15018B/MAX15019B offer a noninverting high-side driver and an inverting low-side driver (see the Selector Guide.) The MAX15018_ feature CMOS (VDD/2) logic inputs. The MAX15019_ feature TTL-logic inputs. The drivers are available in the industry-standard 8-pin SO footprint and pin configuration with a thermally enhanced 8-pin SO package. All devices operate over the -40°C to +125°C automotive temperature range. Features o HIP2100IB/HIP2101IB Pin Compatible (MAX15018A/MAX15019A) o Up to 125V VIN Operation o 8V to 12.6V VDD Input Supply Range o 3A Peak Source and Sink Current o 35ns Propagation Delay o Guaranteed 8ns or Less Propagation Delay Matching Between High- and Low-Side Drivers o Both Noninverting/Noninverting and Noninverting/Inverting Logic-Input Versions Available o Up to 15V Logic Inputs, Independent of VDD Supply Voltage o Low 8pF Input Capacitance o Available in CMOS (VDD/2) or TTL Logic-Level Inputs with Hysteresis o Available in a Space-Saving, Thermally Enhanced 8-Pin SO-EP Package MAX15018/MAX15019 Ordering Information PART MAX15018AASA+ MAX15018BASA+ MAX15019AASA+ MAX15019BASA+ TEMP RANGE -40°C to +125°C -40°C to +125°C -40°C to +125°C -40°C to +125°C PIN-PACKAGE 8 SO-EP* 8 SO-EP* 8 SO-EP* 8 SO-EP* Applications Telecom Power Supplies Synchronous Buck DC-to-DC Converters Half-Bridge, Full-Bridge, and Two-Switch Forward Converters Power-Supply Modules Motor Control +Denotes a lead-free/RoHS-compliant package. *EP = Exposed pad. Internally connected to GND. Typical Operating Circuit VIN = 0 TO 125V Pin Configuration MAX15018A MAX15019A VDD = 8V TO 12.6V BST TOP VIEW + VDD 1 BST 2 DH 3 HS 4 8 DL PWM1 IN_H CBST N VOUT DH HS MAX15018A MAX15018B MAX15019A MAX15019B 7 GND 6 IN_L 5 IN_H PWM2 IN_L VDD DL GND CVDD N SO-EP ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 125V/3A, High-Speed, Half-Bridge MOSFET Drivers MAX15018/MAX15019 ABSOLUTE MAXIMUM RATINGS VDD to GND ............................................................-0.3V to +15V IN_H, IN_L to GND .................................................-0.3V to +15V DL to GND ..................................................-0.3V to (VDD + 0.3V) DH to HS.....................................................-0.3V to (VDD + 0.3V) BST to HS ...............................................................-0.3V to +15V HS to GND (repetitive transient)..............................-5V to +130V HS dv/dt to GND................................................................50V/ns *As per JEDEC Standard 51 (Single-Layer Board). 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. Continuous Power Dissipation (TA = +70°C) Single and Multilayer Board 8-Pin SO-EP (derate 23.8mW/°C above +70°C)*..........1.904W θJC ...................................................................................6°C/W Operating Temperature .....................................-40°C to +125°C Maximum Junction Temperature .....................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C ELECTRICAL CHARACTERISTICS (VDD = VBST = 8V to 12.6V, VHS = VGND = 0V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = VBST = 12V and TA = +25°C.) (Note 1) PARAMETER POWER SUPPLY Operating Supply Voltage VVDD IN_H and IN_L are unconnected (no switching) fSW = 500kHz, VDD = 12V, no capacitive load IN_H and IN_L are unconnected (no switching) fSW = 500kHz, VBST - VHS = 12V, no capacitive load VDD rising 6.5 6.2 MAX15018A/ MAX15018B MAX15019A/ MAX15019B 8.0 65 95 2.75 95 2.75 7.3 6.9 0.5 0.67 x VDD 2 0.33 x VDD 0.8 1.65 0.4 V V 12.6 130 µA 190 3.75 190 3.75 8 7.6 mA µA mA V V V V SYMBOL CONDITIONS MIN TYP MAX UNITS VDD Quiescent Supply Current IDDQ VDD Operating Supply Current BST Quiescent Supply Current BST Operating Supply Current UVLO (VDD to GND) UVLO (BST to HS) UVLO Hysteresis LOGIC INPUT Input-Logic High IDDO IBSTQ IBSTO VDD_UVLO VBST_UVLO VBST rising VIH MAX15018A/MAX15018B (CMOS) MAX15019A/MAX15019B (TTL) V Input-Logic Low VIL MAX15018A/MAX15018B (CMOS) MAX15019A/MAX15019B (TTL) Logic-Input Hysteresis VHYS MAX15018A/MAX15018B (CMOS) MAX15019A/MAX15019B (TTL) 2 _______________________________________________________________________________________ 125V/3A, High-Speed, Half-Bridge MOSFET Drivers ELECTRICAL CHARACTERISTICS (continued) (VDD = VBST = 8V to 12.6V, VHS = VGND = 0V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = VBST = 12V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS IN_H = IN_L = GND (MAX15018A/MAX15019A) Logic-Input Current IIN_ -1 IN_H = GND, IN_L = VDD (MAX15018B/MAX15019B) IN_L to GND (MAX15018A/MAX15019A) Input Resistance Input Capacitance HIGH-SIDE GATE DRIVER HS Maximum Voltage BST Maximum Voltage VHS_MAX VBST_MAX RON_HP Driver Output Resistance RON_HN Power-Off Pulldown Clamp Voltage Peak Output Current LOW-SIDE GATE DRIVER RON_LP Driver Output Resistance RON_LN Power-Off Pulldown Clamp Voltage Peak Output Current INTERNAL BOOTSTRAP DIODE Forward Voltage Drop Turn-On and Turn-Off Time VF tRR IBST = 100mA IBST = 100mA 0.9 40 1.1 V ns IPK_LP IPK_LN VDD = 12V, IDL = 100mA (sourcing) VDD = 12V, IDL = 100mA (sinking) TA = +25°C TA = +125°C TA = +25°C TA = +125°C 1.75 2.3 1.1 1.6 0.88 3 3 2.4 3.0 1.75 2.25 1.2 V A Ω IPK_HP IPK_HN (VBST - VHS) = 12V, IDH = 100mA (sourcing) (VBST - VHS) = 12V, IDH = 100mA (sinking) TA = +25°C TA = +125°C TA = +25°C TA = +125°C 125 140 1.75 2.3 1.1 1.6 0.88 3 3 2.4 3.0 1.75 2.25 1.2 V A Ω V V RIN_ CIN_ IN_L to VDD (MAX15018B/MAX15019B) IN_H to GND 8 pF 5001 kΩ +1 µA MIN TYP MAX UNITS MAX15018/MAX15019 VBST = 0V or unconnected, IDH = 1mA (sinking) VDH = 0V VDH = 12V VDD = 0V or unconnected, IDL = 1mA (sinking) VDL = 0V VDL = 12V _______________________________________________________________________________________ 3 125V/3A, High-Speed, Half-Bridge MOSFET Drivers MAX15018/MAX15019 ELECTRICAL CHARACTERISTICS (continued) (VDD = VBST = 8V to 12.6V, VHS = VGND = 0V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = VBST = 12V and TA = +25°C.) (Note 1) PARAMETER SYMBOL No CL Rise Time tR CL = 1000pF CL = 5000pF CL = 10,000pF No CL Fall Time tF CL = 1000pF CL = 5000pF CL = 10,000pF Figure 1, CL = 1000pF (Note 2) MAX15018A/ MAX15018B (CMOS) MAX15019A/ MAX15019B (TTL) MAX15018A/ MAX15018B (CMOS) MAX15019A/ MAX15019B (TTL) MAX15018A/ MAX15018B (CMOS) MAX15019A/ MAX15019B (TTL) MAX15018A/ MAX15018B (CMOS) MAX15019A/ MAX15019B (TTL) MAX15018A/ MAX15018B (CMOS) MAX15019A/ MAX15019B (TTL) MAX15018A/ MAX15018B (CMOS) MAX15019A/ MAX15019B (TTL) CONDITIONS MIN TYP 1 5 25 50 1 5 20 40 33 36 30 36 1 1 1 1 2 1 2 1 20 60 ns 66 55 ns 66 5 ns 6 5 ns 6 8 ns 6 8 ns 6 ns ns ns MAX UNITS SWITCHING CHARACTERISTICS FOR HIGH- AND LOW-SIDE DRIVERS (VDD = VBST = +12V) Turn-On Propagation Delay Time tD_ON Turn-Off Propagation Delay Time tD_OFF Figure 1, CL = 1000pF (Note 2) Delay Matching Between High-Side Turn-On to Low-Side Turn-On tMATCH1 CL = 1000pF (Note 2) Delay Matching Between High-Side Turn-Off to Low-Side Turn-Off tMATCH2 CL = 1000pF (Note 2) Delay Matching Between High-Side Turn-Off to Low-Side Turn-On tMATCH3 CL = 1000pF (Note 2) Delay Matching Between High-Side Turn-On to Low-Side Turn-Off Minimum Input Pulse Width for Output Change tMATCH4 CL = 1000pF (Note 2) tPW Note 1: All devices are 100% production tested at TA = TJ = +125°C. Limits over temperature are guaranteed by design and characterization. Note 2: Guaranteed by design, not production tested. 4 _______________________________________________________________________________________ 125V/3A, High-Speed, Half-Bridge MOSFET Drivers Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) MAX15018/MAX15019 VDD AND BST UNDERVOLTAGE LOCKOUT vs. TEMPERATURE MAX15018 toc01 VDD AND BST UNDERVOLTAGE LOCKOUT HYSTERESIS vs. TEMPERATURE MAX15018 toc02 UNDERVOLTAGE LOCKOUT RESPONSE (VDD RISING) 12V 7.5 7.4 7.3 7.2 VUVLO (V) 7.1 7.0 6.9 6.8 6.7 6.6 6.5 VBST - VHS RISING VDD RISING 0.60 0.58 0.56 HYSTERESIS (V) 0.54 0.52 0.50 0.48 0.46 0.44 0.42 0.40 VBST - VHS VDD MAX15018 toc03 VDD 2V/div 7.3V 4V VDH 5V/div VDL 5V/div -40 -25 -10 5 20 35 50 65 80 95 110 125 AMBIENT TEMPERATURE (°C) -40 -25 -10 5 20 35 50 65 80 95 110 125 AMBIENT TEMPERATURE (°C) 40µs/div UNDERVOLTAGE LOCKOUT RESPONSE (VDD FALLING) 12V MAX15018A IDDO + IBSTO CURRENT vs. VDD (250kHz SWITCHING) MAX15018 toc05 INTERNAL BOOTSTRAP DIODE I-V CHARACTERISTICS 180 160 DIODE CURRENT (mA) 140 120 100 80 60 40 20 0 TA = +125°C TA = +150°C TA = -40°C TA = 0°C TA = +25°C MAX15018 toc06 MAX15018 toc04 5.0 4.5 4.0 IDD + IBST (mA) VDD 2V/div VDD = VBST 200 6.8V 4V 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 VDD (V) VDD FALLING VDD RISING VDH 5V/div VDL 5V/div 40µs/div 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 VDD - VBST (V) MAX15018A VDD QUIESCENT CURRENT vs. VDD (NO SWITCHING) MAX15018 toc07 MAX15018A BST QUIESCENT CURRENT vs. VBST (NO SWITCHING) MAX15018 toc08 MAX15018A IDD AND IBST vs. SWITCHING FREQUENCY VDD = VBST = 12V NO LOAD IDD MAX15018 toc09 160 140 120 IDD (µA) 100 80 60 40 20 0 VDD FALLING 140 120 100 IBST (µA) 80 60 40 20 VBST FALLING 6 5 SUPPLY CURRENT (mA) 4 3 2 1 0 TA = +150°C TA = +125°C TA = +125°C TA = +25°C TA = 0°C IBST TA = -40°C TA = -40°C, 0°C, +25°C 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 VDD (V) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 VBST (V) 0 200 400 600 800 1000 SWITCHING FREQUENCY (kHz) _______________________________________________________________________________________ 5 125V/3A, High-Speed, Half-Bridge MOSFET Drivers MAX15018/MAX15019 Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) DH OR DL OUTPUT LOW VOLTAGE vs. TEMPERATURE MAX15018 toc10 DH AND DL OUTPUT HIGH VOLTAGE vs. TEMPERATURE MAX15018 toc11 PEAK OUTPUT CURRENT vs. OUTPUT VOLTAGE 3.5 3.0 MAX15018 toc12 200 180 OUTPUT VOLTAGE (mV) 160 140 120 100 80 60 300 280 260 OUTPUT VOLTAGE (mV) 240 SINKING 100mA SOURCING 100mA 4.0 200 180 160 140 120 100 VBST - VDH IOUT (A) 220 VDD - VDL 2.5 2.0 1.5 1.0 SINK (NMOS) 0.5 0 SOURCE (PMOS) -40 -25 -10 5 20 35 50 65 80 95 110 125 AMBIENT TEMPERATURE (°C) -40 -25 -10 5 20 35 50 65 80 95 110 125 AMBIENT TEMPERATURE (°C) 01 2 34 5 6 7 8 9 10 11 12 VDH OR VDH (V) DH OR DL OUTPUT RISE TIME vs. TEMPERATURE 90 80 70 FALL TIME (ns) RISE TIME (ns) 60 50 40 30 20 10 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 AMBIENT TEMPERATURE (°C) 10,000pF LOAD MAX15018 toc13 DH OR DL OUTPUT FALL TIME vs. TEMPERATURE MAX15018 toc14 DH OR DL RISING PROPAGATION DELAY vs. TEMPERATURE MAX15018 toc15 100 100 90 80 70 60 50 40 30 20 10 0 10,000pF LOAD 60 50 PROPAGATION DELAY (ns) 40 30 MAX15018 20 10 0 MAX15019 -40 -25 -10 5 20 35 50 65 80 95 110 125 AMBIENT TEMPERATURE (°C) -40 -25 -10 5 20 35 50 65 80 95 110 125 AMBIENT TEMPERATURE (°C) DH OR DL FALLING PROPAGATION DELAY vs. TEMPERATURE MAX15018 toc16 DELAY MATCHING (DH AND DL RISING) MAX15018 toc17 60 50 PROPAGATION DELAY (ns) 40 30 20 10 MAX15018 MAX15019 VIN_ 10V/div VDH AND VDL 10V/div CL = 0pF 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 AMBIENT TEMPERATURE (°C) 10ns/div 6 _______________________________________________________________________________________ 125V/3A, High-Speed, Half-Bridge MOSFET Drivers Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) MAX15018/MAX15019 DELAY MATCHING (DH AND DL RISING) MAX15018 toc18 RESPONSE TO VDD GLITCH MAX15018 toc19 VIN_ 10V/div 10V/div VDH_ VDL VDH AND VDL 10V/div VDD 10V/div 10V/div CL = 0pF 10ns/div VIN_ 40µs/div 10V/div Pin Description PIN 1 2 3 4 5 6 7 8 — NAME VDD BST DH HS IN_H IN_L GND DL EP FUNCTION Input Supply Voltage. Valid supply voltage ranges from 8V to 12.6V. Bypass VDD to GND with a parallel combination of 0.1µF and 1µF ceramic capacitors as close to the IC as possible. Boost Flying Capacitor Connection. Connect a 0.22µF ceramic capacitor from BST to HS as close to the IC as possible for the high-side MOSFET driver supply. High-Side Gate Driver Output. Driver output for the high-side MOSFET gate. Source Connection for High-Side MOSFET. Also serves as the return for the high-side driver. High-Side Noninverting Logic Input Low-Side Noninverting (MAX15018A/MAX15019A) or Low-Side Inverting (MAX15018B/MAX15019B) Input Ground. Use GND as a return path to the DL driver output and the IN_H, IN_L inputs. Must be connected to ground. Low-Side Gate Driver Output. Driver output for the low-side MOSFET gate. Exposed Pad. Internally connected to GND. Externally connect the exposed pad to a large ground plane to aid in heat dissipation. Grounding EP does not substitute the requirement to connect GND to ground. _______________________________________________________________________________________ 7 125V/3A, High-Speed, Half-Bridge MOSFET Drivers MAX15018/MAX15019 Detailed Description The MAX15018A/MAX15018B/MAX15019A/MAX15019B half-bridge, n-channel MOSFET drivers control highand low-side MOSFETs in high-voltage, high peak-current applications and offer a high 125V voltage range that allows ample margin above the 100V transient specification of telecom standards. These drivers operate with an IC supply voltage of 8V to 12.6V, and consume only 2.75mA of supply current during typical switching operations. The MAX15018_/MAX15019_ provide 3A (typ) sink/source peak current per output and are capable of operating with large capacitive loads and with switching frequencies near 1MHz. These drivers are intended to be used to drive the high-side MOSFET without requiring an isolation device such as an optocoupler or a drive transformer. The high-side driver is controlled by a TTL/CMOS logic signal referenced to ground and is powered by a bootstrap circuit formed by an integrated diode and an external capacitor. Undervoltage lockout (UVLO) protection is provided for both the high- and low-side driver supplies (BST and V DD ) and includes a UVLO hysteresis of 0.5V (typ). The drivers are independently controlled and feature exceptionally fast switching times, very short propagation delays (35ns typ), and matched propagation delaytimes (2ns typ) between drivers, making them ideally suited for high-frequency applications. Internal logic circuitry prevents shoot-through during output state changes and minimizes package power dissipation. These devices are available with CMOS (VDD/2) or TTL logic-level inputs. The MAX15018A/MAX15018B accept CMOS input logic levels, while the MAX15019A/ MAX15019B accept TTL input logic levels. For both versions, the logic inputs are protected against voltage spikes up to +15V, regardless of VDD. See the Driver Logic Inputs (IN_H, IN_L) section. The MAX15018_/MAX15019_ are available with both high-side and low-side noninverting logic inputs or with noninverting high-side and inverting low-side logic inputs. See the Functional Diagrams and Selector Guide. The MAX15018A and MAX15019A are pin-for-pin replacements for the HIP2100IB and HIP2101IB, respectively. The MAX15018_/MAX15019_ are available in a spacesaving, high-power, 8-pin SO-EP package that can dissipate up to 1.95W at +70°C. All devices operate over the -40°C to +125°C automotive temperature range. Undervoltage Lockout Both the high- and low-side drivers feature separate UVLO protection that monitors each driver’s input supply voltage (BST and VDD). The low-side driver UVLO threshold (VDD_UVLO) is referenced to GND and pulls both driver outputs low when VDD falls below 7.3V (typ). The high-side driver UVLO threshold (VBST_UVLO) is referenced to HS, and only pulls DH low when VBST falls below 6.9V (typ) with respect to HS. After the IC is first energized, and once VDD rises above its UVLO threshold, DL starts switching and either follows the IN_L logic input (MAX15018A/MAX15019A) or is inverted with reference to the IN_L logic input (MAX15018B/ MAX15019B). At this time, the bootstrap capacitor is not charged, and DH does not switch since the BST-to-HS voltage is below VBST_UVLO. Within a short time following engagement of low-side switching, CBST charges through VDD and causes VBST to exceed VBST_UVLO. DH then starts switching and follows IN_H. For synchronous buck and half-bridge converter topologies, the bootstrap capacitor can charge up in one cycle. Normal operation then begins in a few microseconds after the BST-to-HS voltage exceeds V BST_UVLO. In the twoswitch forward topology, CBST takes more time (a few hundred microseconds) to charge and increase its voltage above VBST_UVLO. The typical hysteresis for both UVLO thresholds is 0.5V. The bootstrap capacitor value should be selected carefully to avoid oscillations during turn-on and turn-off at the DH output. Choose a capacitor value 20 times greater than the total gate capacitance of the MOSFET. Use a low ESR-type X7R dielectric ceramic capacitor at BST (typically a 0.1µF ceramic is adequate) and a parallel combination of 1µF and 0.1µF ceramic capacitors from VDD to GND. The high-side MOSFET’s continuous on-time is limited due to the charge loss from the high-side driver’s quiescent current. The maximum on-time is dependent on the size of CBST, IBST (190µA, max), and VBST_UVLO. 8 _______________________________________________________________________________________ 125V/3A, High-Speed, Half-Bridge MOSFET Drivers Output Driver The MAX15018_/MAX15019_ drivers contain low onresistance p-channel and n-channel devices in a totem pole configuration for the driver output stage. This allows for rapid turn-on and turn-off of high gate-charge (Qg) external switching MOSFETs. The drivers exhibit low drain-to-source resistance (RDS_ON), which decreases for higher values of VDD and for lower operating temperatures. Lower RDS_ON means higher source and sink currents from the IC, and results in faster switching speeds, since the external MOSFET gate capacitance will charge and discharge at a quicker rate. The peak source and sink current provided by the drivers is typically 3A. Propagation delay from the logic inputs to the driver outputs is matched to within 8ns (max) between the low-side and high-side drivers. Turn-on and turn-off propagation delays are typically 35ns and 36ns. See Figure 1. The internal drivers also contain break-beforemake logic to eliminate shoot-through conditions that would cause unnecessarily high operating supply currents, efficiency reduction, and voltage spikes at VDD. Voltage at DL is approximately equal to VDD when in a high state, and zero when in a low state. Voltage from DH to HS is approximately equal to V DD minus the diode drop of the integrated bootstrap diode when in a high state, and zero when in a low state. The high-side MOSFET’s continuous on-time is limited due to the charge loss from the high-side driver’s quiescent current. The maximum on-time is dependent on the size of the bootstrap capacitor (CBST), IBST (190µA max), and VBST_UVLO. MAX15018/MAX15019 Integrated Bootstrap Diode An integrated diode between VDD and BST is used in conjunction with an external bootstrap capacitor (CBST) to provide the voltage required to turn on the high-side MOSFET (see the Typical Operating Circuit). The internal diode charges the bootstrap capacitor from VDD when the low-side switch is on, and isolates VDD when HS is pulled high when the high-side driver turns on. The internal bootstrap diode has a typical forward voltage drop of 0.9V and has a 40ns (typ) turn-off/-on time. The turn-off time (reverse recovery time) depends on the reverse-recovery current and can be as low as 10ns. If a lower diode voltage-drop between VDD and BST is needed, connect an external Schottky diode between VDD and BST. VIH IN_L VIL 90% DL 10% tD_OFF1 tF VIH IN_H VIL tD_ON1 tR 90% DH tD_OFF1 tF tD_ON2 tR 10% tMATCH = (tD_ON2 - tD_ON1) OR (tD_OFF2 - tD_OFF1) Figure 1. Timing Characteristics of Logic Inputs (MAX15018A/MAX15019A) _______________________________________________________________________________________ 9 125V/3A, High-Speed, Half-Bridge MOSFET Drivers MAX15018/MAX15019 Bootstrap Capacitor The bootstrap capacitor is used to ensure adequate charge is available to switch the high-side MOSFET. This capacitor is charged from VDD through the internal bootstrap diode when the low-side MOSFET is on. The bootstrap capacitor value should be selected carefully to avoid oscillations during turn-on and turn-off at the DH output. Choose a capacitor value approximately 20 times greater than the total gate capacitance of the MOSFET being switched. Use a low-ESR, X7R-type dielectric ceramic capacitor (typically a 0.1µF ceramic is adequate). The high-side MOSFET’s continuous ontime is limited due to the charge loss from the high-side driver’s quiescent current. The maximum on-time is dependent on the size of CBST, IBST (190µA max), and VBST_UVLO. Note that the bootstrap capacitor requires time to charge up to VDD, according to the time constant of the charging loop through the lower MOSFET (see the Typical Operating Circuit ). Ensure that the lower MOSFET is on for at least the minimum time required to charge CBST. exceed 6A when both drivers are simultaneously driving large external capacitive loads in phase. Supply drops and ground shifts create forms of negative feedback for inverterting topologies and may degrade the delay and transition times. Ground shifts due to insufficient device grounding may also disturb other circuits sharing the same AC ground return path. Any series inductance in the VDD, DH, DL, and/or GND paths can cause oscillations due to the very high di/dt when switching the MAX15018_/MAX15019_ with any capacitive load. Place one or more 0.1µF ceramic capacitors in parallel from V DD to GND as close as possible to the device to bypass the input supply. Use a ground plane to minimize ground return resistance and series inductance. Place the external MOSFETs as close as possible to the MAX15018_/MAX15019_ to reduce trace length and further minimize board inductance and AC path resistance. Power Dissipation Power dissipation in the MAX15018_/MAX15019_ is primarily due to power loss in the internal boost diode and the internal nMOS and pMOS FETS. For capacitive loads, the total power dissipation for the device is: PD = (CL x VDD2 x fSW) + (IVDDO + IBSTO) x VDD where CL is the combined capacitive load at DH and DL, VDD is the supply voltage, and fSW is the switching frequency of the IC. PD includes the power dissipated in the internal bootstrap diode (P DIODE ). The internal power dissipation reduces by PDIODE, if an external bootstrap Schottky diode is used. The power dissipation in the internal boost diode (when driving a capacitive load) will be the charge through the diode per switching period multiplied by the maximum diode forward voltage drop (VF = 1V) as given in the following equation. PDIODE = CDH x (VDD - 1) x fSW x VF where CDH is the capacitive load at DH, VDD is the supply voltage, fSW is the switching frequency of the converter, VF is the maximum diode forward voltage drop. The total power dissipation when using the internal boost diode will be PD and, when using an external Schottky diode, will be PD - PDIODE. The total power dissipated in the device must be kept below the maximum of 1.95W for the 8-pin SO with exposed pad at TA = +70°C ambient. Driver Logic Inputs (IN_H, IN_L) The MAX15018_ are CMOS (VDD/2) logic-input drivers, and the MAX15019_ are TTL-compatible logic-input drivers. The required logic-input levels are independent of VDD. For example, the IC can be powered by a 10V supply while the logic inputs are provided from 12V CMOS logic. Additionally, the logic inputs are protected against voltage spikes up to 15V, regardless of VDD voltage. The TTL and CMOS logic inputs have 400mV and 1.6V hysteresis, respectively, to avoid double pulsing during signal transition. The logic inputs are high-impedance pins (500k Ω typ) and should not be left unconnected to ensure the input logic state is at a known level. With the logic inputs unconnected, the DH and DL outputs pull low as VDD rises up above the UVLO threshold. The PWM output from the controller must assume a proper state while powering up the device. Applications Information Supply Bypassing and Grounding Careful attention is required when choosing the bypassing and grounding scheme of the MAX15018_/ MAX15019_. Peak supply and output currents may 10 ______________________________________________________________________________________ 125V/3A, High-Speed, Half-Bridge MOSFET Drivers Layout Information The MAX15018_/MAX15019_ drivers source and sink large currents to create very fast rise and fall edges at the gates of the switching MOSFETs. The high di/dt can cause unacceptable ringing if the trace lengths and impedances are not well controlled. Use the following PCB layout guidelines when designing with the MAX15018_/MAX15019_: • It is important that the VDD voltage (with respect to ground) or BST voltage (with respect to HS) does not exceed 15V. Voltage spikes higher than 15V from V DD to GND or from BST to HS can damage the device. Place one or more low-ESL 0.1µF decoupling ceramic capacitors from VDD to GND and from BST to HS as close as possible to the part. The ceramic decoupling capacitors should be at least 20 times the gate capacitance being driven. • There are two AC current loops formed between the IC and the gate of the MOSFET being driven. The MOSFET looks like a large capacitance from gate to source when the gate is being pulled low. The active current loop is from the MOSFET driver output (DL or DH) to the MOSFET gate, to the MOSFET source, and to the return terminal of the MOSFET driver (either GND or HS). When the gate of the MOSFET is being pulled high, the active current loop is from the MOSFET driver output, (DL or DH), to the MOSFET gate, to the MOSFET source, to the return terminal of the drivers decoupling capacitor, to the positive terminal of the decoupling capacitor, and to the supply connection of the MOSFET driver. The decoupling capacitor will be either CBST for the high-side MOSFET or the VDD decoupling capacitor for the low-side MOSFET. Care must be taken to minimize the physical distance and the impedance of these AC current paths. • Solder the exposed pad of the 8-pin SO-EP package to a large copper plane to achieve the rated power dissipation. MAX15018/MAX15019 Typical Application Circuits VDD = 8V TO 12.6V VIN = 0 TO 125V VDD BST DH N PWM1 IN_H MAX15018A HS N VOUT PWM2 IN_L GND DL N N Figure 2. Half-Bridge Converter Application with Secondary-Side Synchronous Rectification ______________________________________________________________________________________ 11 125V/3A, High-Speed, Half-Bridge MOSFET Drivers MAX15018/MAX15019 Typical Application Circuits (continued) VDD = 8V TO 12.6V VIN = 0 TO 125V VDD BST DH N HS IN_H PWM VOUT MAX15018A MAX15019A IN_L DL GND N Figure 3. Two-Switch Forward Application 12 ______________________________________________________________________________________ 125V/3A, High-Speed, Half-Bridge MOSFET Drivers Functional Diagrams MAX15018/MAX15019 MAX15018A VDD/2 CMOS BST IN_H DH HS VDD IN_L DL GND IN_L MAX15018B VDD/2 CMOS BST IN_H DH HS VDD DL GND IN_L MAX15019A TTL BST IN_H DH HS VDD DL GND IN_L MAX15019B TTL BST IN_H DH HS VDD DL GND SO-EP SO-EP SO-EP SO-EP Selector Guide PART MAX15018AASA+ MAX15018BASA+ MAX15019AASA+ MAX15019BASA+ HIGH-SIDE DRIVER Noninverting Noninverting Noninverting Noninverting LOW-SIDE DRIVER Noninverting Inverting Noninverting Inverting LOGIC LEVEL CMOS (VDD/2) CMOS (VDD/2) TTL TTL PIN COMPATIBLE HIP 2100IB — HIP 2101IB — Chip Information PROCESS: BiCMOS PACKAGE TYPE 8 SO Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE CODE S8E-14 DOCUMENT NO. 21-0111 ______________________________________________________________________________________ 13 125V/3A, High-Speed, Half-Bridge MOSFET Drivers MAX15018/MAX15019 Revision History REVISION NUMBER 0 1 REVISION DATE 5/08 9/08 Initial release Removed future product asterisk for the MAX15018B. DESCRIPTION PAGES CHANGED — 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.