MAX25256ATBA/V+

Click here for production status of specific part numbers. MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies General Description Benefits and Features The MAX25256 H-bridge transformer driver provides a simple solution for making isolated power supplies up to 10W. The device drives a transformer’s primary coil with up to 300mA of current from a wide 8V to 36V direct current (DC) supply. The transformer’s secondary-to-primary winding ratio defines the output voltage, allowing selection of virtually any isolated output voltage. • Simple, Flexible Design • 8V to 36V Supply Range • Up to 90% Efficiency • Provides Up to 10W to the Transformer • Undervoltage Lockout (UVLO) • 2.5V to 5V Compatible Logic Interface • Internal or External Clock Source • Adjustable Overcurrent Threshold The device features adjustable current limiting, allowing indirect limiting of secondary-side load currents. The current limit of the MAX25256 is set by an external resistor. A output asserts when the device detects an overtemperature or overcurrent condition. In addition, the device features a low-power mode to reduce the overall supply current to 0.65mA (typ) when the driver is not in use. • Integrated System Protection • Fault Detection and Indication • Overcurrent Limiting • Overtemperature Protection • Saves Space on Board • Small 10-Pin TDFN Package (3mm x 3mm) • AECQ-100 Qualified The device can be operated using the internal oscillator or driven by an external clock to synchronize multiple MAX25256 devices and precisely set the switching frequency. Internal circuitry guarantees a fixed 50% duty cycle to prevent DC flow through the transformer, regardless of which clock source is used. The device is available in a small 10-pin (3mm x 3mm) TDFN package and is specified over the -40°C to +125°C automotive temperature range. Applications • • • • Isolated Gate Driver Supplies Isolated Supplies for Motor Control Dual-Battery Systems Isolated Supplies for controller area network (CAN), serial peripheral interface (SPI), I2C, etc. 19-101087; Rev 0; 4/21 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Simplified Block Diagram VIN CIN 1µF VDD 4.6k VOUT n:1 FAULT ST1 EN CLK COUT 2-4µF MAX25256 ST2 ITH RLIM GND Absolute Maximum Ratings VDD, ...................................................... -0.3V to +40V Operating Temperature Range ...................... -40°C to +125°C ST1, ST2 ............................................... -0.3V to (VDD + 0.3V) Operating Junction Temperature (Note 1) .................... +150°C CLK, ITH, Storage Temperature Range ......................... -65°C to +150°C ........................................................ -0.3V to +6V Continuous Current .......................................... ±50mA ST1, ST2 Continuous Current .................................... ±850mA Lead Temperature (soldering, 10s) .............................. +300°C Soldering Temperature (reflow).................................... +260°C TDFN (Single-Layer Board) (Derate 18.5mW/°C above +70°C) ............................................................................... 1481.5mW 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. Package Information 10 TDFN-EP Package Code T1033+1C Outline Number 21-0137 Land Pattern Number 90-0003 Thermal Resistance, Single-Layer Board: www.maximintegrated.com Maxim Integrated | 2 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Junction-to-Ambient (θJA) 54°C/W Junction-to-Case Thermal Resistance (θJC) 9°C/W Thermal Resistance, Four-Layer Board: Junction-to-Ambient (θJA) 41°C/W Junction-to-Case Thermal Resistance (θJC) 9°C/W For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Electrical Characteristics (VDD = 8V to 36V, V = 0V, TA = -40°C to +125°C unless otherwise noted, Typical values are at TA = +25°C (Note 2)) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC CHARACTERISTICS Supply Voltage Range VDD (Note 3) Supply Current IDD V = 0.8V, VCLK = 0V, RLIM = 1000Ω, ST1/ST2 not connected 6 11 Disable Supply Current IDIS V = 3.3V, VCLK = 0V 0.7 1.1 ROH ST1 = ST2 = high, IST1, ST2 = +300mA, RLIM = 1000Ω 1 1.8 ROL ST1 = ST2 = low, IST1, ST2 = -300mA, RLIM = 1000Ω 0.6 1.0 6.3 6.9 Driver Output Resistance UndervoltageLockout Threshold VUVLO UndervoltageLockout Threshold Hysteresis VUVLO_HYST VDD rising ILIM ST1, ST2 Leakage Current LOGIC SIGNALS (CLK, ILKG RLIM = 3010Ω, VDD = 24V V = 3.3V, VCLK = 0V, VST1 = VST2 = 0V or VDD, TA = +25°C V mA mA Ω 5.9 500 650 V mV 800 mA 165 -1 215 265 +1 µA ) Input Logic-High Voltage VIH Input Logic-Low Voltage VIL www.maximintegrated.com 36 300 RLIM = 1000Ω, VDD = 24V ST1, ST2 Current Limit 8 2 V 0.8 V Maxim Integrated | 3 MAX25256 (VDD = 8V to 36V, V Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies = 0V, TA = -40°C to +125°C unless otherwise noted, Typical values are at TA = +25°C (Note 2)) PARAMETER Input Leakage Current Output LogicLow Voltage SYMBOL IIL CONDITIONS VCLK = V = 5.5V or 0V MIN TYP -1 MAX UNITS +1 µA 1 V 10 µA VOL I = 10mA ILKGF V = 36V, Switching Frequency fSW VCLK = 0V, measured at ST1/ST2 outputs 255 700 kHz CLK Input Frequency fEXT External clocking 200 2000 kHz Internal or external clocking, Fext1000kHz (Note 4) 48 49 50 Leakage Current deasserted AC CHARACTERISTICS ST1/ST2 Duty Cycle DTC % ST1/ST2 Rise Time tRISE ST1/ ST2 = 20% to 80% of VDD, RL = 1kΩ, CL = 50pF, Figure 1A 100 ST1/ST2 Fall Time tFALL ST1/ST2 = 80% to 20% of VDD, RL = 1kΩ, CL = 50pF, Figure 1A 100 Crossover Dead Time tDEAD Watchdog Timeout tWDOG (Note 5), VDD = 36V 20 32 55 Current-Limit Blanking Time tBLANK Figure 2, VDD = 36V 0.73 1.2 2.0 Current-Limit Autoretry Time tRETRY Figure 2, VDD = 36V 23.4 38.4 64.0 RL = 200Ω, Figure 1B ns ns ns 30 µs ms ms PROTECTION Thermal-Shutdown Threshold TSHDN Thermal-Shutdown Hysteresis TSHDN_HYS +160 °C 10 °C Note 1: Limits are 100% tested at TA = +25°C. Limits over the operating temperature range and relevant supply voltage are guaranteed by design and characterization. Typical values are at T A = +25°C. Note 2: If VDD is greater than 27V, see the Snubber section. Note 3: Guaranteed by design and simulation; not production tested. Note 4: See the Watchdog section. www.maximintegrated.com Maxim Integrated | 4 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Test Circuits/Timing Diagrams ST1/ST2 ST1 CL RL RL ST2 (B) (A) VDD 80% 80% ST1 0V 20% 20% tDEAD VDD tRISE tFALL ST2 0V (C) Figure 1. Test Circuits (A and B) and Timing Diagram (C) for Rise, Fall, and Dead Times ILIM IST1,ST2 50% tBLANK 50% tRETRY 50% 0mA Figure 2. Timing Diagram for Current Limiting www.maximintegrated.com Maxim Integrated | 5 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Typical Operating Characteristics VDD = 24V, TA = +25oC, unless otherwise stated www.maximintegrated.com Maxim Integrated | 6 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies VDD = 24V, TA = +25oC, unless otherwise stated Pin Configurations Pin Descriptions PIN 1,2 NAME VDD 3 CLK Power Supply. Bypass VDD to ground with a 1µF capacitor as close as possible to the device. Clock Input. Connect CLK to GND to enable internal clocking. Apply a clock signal to CLK to enable external clocking. Enable Input. Drive 4 5 FUNCTION ITH low to enable the device. Drive high to disable the device. Overcurrent Threshold Adjustment Input. Connect a resistor (RLIM) from ITH to GND to set the overcurrent threshold for the ST1 and ST2 outputs. Do not exceed 10pF of capacitance to GND on ITH. Open-Drain Output. The fault open-drain transistor turns on when there is either an overtemperature or overcurrent condition. 6 7,9 GND Ground 8 ST2 Transformer Drive Output 2 10 ST1 Transformer Drive Output 1 — EP Exposed Pad. Internally connected to GND. Connect EP to a large ground plane to maximize thermal performance; not intended as an electrical connection point. www.maximintegrated.com Maxim Integrated | 7 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Functional Diagrams VDD VDD MAX25256 UVLO P ST1 OSC VUVLO N CLK MUX FLIPFLOP MOSFET H-BRIDGE DRIVER VDD P WATCHDOG EN ITH ST2 CURRENT LIMIT FAULT N GND Detailed Description The MAX25256 is an integrated primary-side controller and H-bridge driver for isolated power-supply circuits. The device contains an on-board oscillator, protection circuitry, and internal metal-oxide semiconductor field-effect transistors (MOSFETs) to provide up to 300mA of current to the primary winding of a transformer. The device can be operated using the internal oscillator or driven by an external clock to synchronize multiple MAX25256 devices and control EMI behavior. Regardless of the clock source being used, an internal flip-flop stage guarantees a fixed 50% duty cycle to prevent DC flow in the transformer as long as the period of the clock is constant. The device operates from a wide single-supply voltage of 8V to 36V and includes UVLO for controlled startup. The device features break-before-make switching to prevent cross conduction of the H-bridge MOSFETs. An external resistor sets an overcurrent limit, allowing primary-side limiting of load currents on the transformer’s secondary side. The thermalshutdown circuitry provides additional protection against excessive power dissipation. Power-Up and Undervoltage Lockout The MAX25256 provides an undervoltage-lockout feature to both ensure a controlled power-up state and prevent operation before the oscillator has stabilized. On power-up and during normal operation if the supply voltage drops below VUVLO, the undervoltage-lockout circuit forces the device into disable mode. The ST1 and ST2 outputs are high impedance in disable mode. www.maximintegrated.com Maxim Integrated | 8 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Isolated Power Supply The MAX25256 allows a versatile range of secondary-side rectification circuits (see Figure 3). The primary-to-secondary transformer winding ratio can be chosen to adjust the isolated output voltage. The device delivers up to 300mA of current to the transformer with a supply up to +36V. The MAX25256 provides the advantages of the H-bridge converter topology, including multiple isolated outputs, stepup/step-down or inverted output, relaxed filtering requirements, and low-output ripple. n:1 VOUT = 1/(2 x n) x VIN/ - VD VIN VD=DIODE FORWARD VOLTAGE (A) PUSH-PULL RECTIFICATION n:1 VOUT = 2(VIN/n - VD) VIN (B) VOLTAGE DOUBLER n:1 VIN VOUT = VIN/n - 2VD (C) FULL-WAVE RECTIFIER Figure 3. Secondary-Side Rectification Topologies Clock Source Either the internal oscillator or an external clock provides the switching signal for the MAX25256. Connect CLK to ground to select the internal oscillator. Provide a clock signal to CLK to automatically select external clocking. Internal Oscillator Mode The MAX25256 includes an internal oscillator that drives the H-bridge when a watchdog timeout is detected on CLK. The outputs switch at 425kHz (typ) with a duty cycle of 50%, guaranteed by design, in the internal oscillator mode. Transients on ST1/ST2 During tDEAD When the MAX25256 switches, there is a period of time when both ST1 and ST2 are high impedance to ensure that there are no shoot-through currents in the H-bridge. During this dead time, the voltage at these pins may temporarily exceed the absolute maximum ratings due to the inductive load presented by the transformer. This transient voltage does not damage the device. www.maximintegrated.com Maxim Integrated | 9 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Disable Mode The MAX25256 provides a disable mode to reduce current consumption. The ST1 and ST2 outputs are high impedance in disable mode. Watchdog A stalled clock could cause excessive DC to flow through the primary winding of the transformer. The MAX25256 features an internal watchdog circuit to prevent damage from this condition. The internal oscillator provides the switching signal to the H-bridge whenever the period between edges on CLK exceeds the watchdog timeout period of 20µs (min). External Clock Mode The MAX25256 provides an external clock mode. When an external clock source is applied to CLK, the external clock drives the H-bridge. An internal flip-flop divides the external clock by two in order to generate a switching signal with a 50% duty cycle. As a result, the device outputs switch at one-half of the external clock frequency. The device switches on the rising edge of the external clock signal. Note: There is a fixed asymmetric delay which reduces the ON-time by 10ns and hence the actual duty cycle observed at the output will be slightly lower than 50%, depending on the clock frequency. Overcurrent Limiting The MAX25256 limits the ST1/ST2 output current. Connect an external resistor (RLIM) to ITH to set the current limit. When the current reaches the limit for longer than the blanking time of 1.2ms (typ), the drivers are disabled and is asserted low. The drivers are re-enabled after the autoretry time of 38.4ms (typ). If a continuous fault condition is present, the duty cycle of the fault current is approximately 3%. To set the current-limit threshold, use the following equation: 𝑅𝐿𝐼𝑀 (kΩ) = 650 𝐼𝐿𝐼𝑀 (𝑚𝐴) where ILIM is the desired current threshold in the range of 215mA < ILIM < 650mA (typ). For example, a 1kΩ resistor sets the current limit to 650mA. Use a 1% resistor for RLIM for increased accuracy. Ensure that the overcurrent threshold is set to at least twice the expected maximum operating current. For an expected maximum operating current of 300mA, set the ILIM to 650mA. For an expected operating current of 100mA, set the ILIM to 215mA. Thermal Shutdown The MAX25256 is protected from overtemperature damage by a thermal-shutdown circuit. When the junction temperature (TJ) exceeds +160°C, the device is disabled and is asserted low. stays low for the duration of an overtemperature fault. The device resumes normal operation when TJ falls below +150°C. FAULT Output The output is asserted low whenever the device is disabled due to a fault condition. is automatically deasserted when the device is enabled after the autoretry time following an overcurrent fault, resulting in toggling during a continuous overcurrent condition. is asserted for the entire duration of an overtemperature fault. is an open-drain output. Applications Information Snubber For VDD greater than 27V, use a simple resistor-capacitor (RC) snubber circuit on ST1 and ST2 to ensure that the peak voltage is less than 40V during switching (Figure 4). Recommended values for the snubber are R = 91Ω and C = 330pF. www.maximintegrated.com Maxim Integrated | 10 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies n:1 ST1 ST2 R=91Ω C=330pF C=330pF Figure 4. Output Snubber Power Dissipation The power dissipation of the device is approximated by: PD = (ROHL x IPRI2) + (IDD x VDD) where ROHL is the combined high-side and low-side on resistance of the internal field-effect transistors (FET) drivers, and IPRI is the load current flowing through ST1 and ST2. High-Temperature Operation When the MAX25256 is operated under high ambient temperatures, the power dissipated in the package can raise the junction temperature close to thermal shutdown. Under such temperature conditions, the power dissipation should be held low enough so that the junction temperature observes a factor of safety margin. The maximum junction temperature should be held below +150°C. Use the package’s thermal resistances to calculate the junction temperature. Alternatively, use the Maximum Output Current vs Temperature curves shown in the Typical Operating Characteristics section to determine the maximum ST1/ST2 load currents. Hot Insertion If the MAX25256 is inserted into a live backplane, it is possible to damage the device. Damage is caused by overshoot on VDD exceeding the absolute maximum rating. Limit the transient input voltage to the MAX25256 with an external protection device. Output Ripple Filtering Output-voltage ripple can be reduced with a low-pass LC filter (see Figure 5). The component values shown give a cutoff frequency of 21.5kHz by the following equation: 𝑓3𝑑𝐵 = 1 2𝜋√𝐿𝐶 Use an inductor with low DC resistance and sufficient saturation current rating to minimize the filter power dissipation. L=25µH FILTER OUTUT C=2.2µF Figure 5. Output Ripple Filtering Power Supply Decoupling Bypass VDD to ground with a 1µF ceramic capacitor as close as possible to the device. www.maximintegrated.com Maxim Integrated | 11 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Output Voltage Regulation For many applications, the unregulated output of the MAX25256 meets the output-voltage tolerances. This configuration represents the highest efficiency possible with the device. For applications requiring a regulated output voltage, Maxim provides several solutions. In the following examples, assume a tolerance of ±10% for the input voltage. When the load currents on the transformer’s secondary side are low, the output voltage can significantly increase. If operation under low-load currents is expected, output voltage limiting should be used to keep the voltage within the tolerance range of the subsequent circuitry. If the minimum output load current is less than approximately 5mA, connect a zener diode from the output node to ground as shown in Figure 6 to limit the output voltage to a safe value. Example 1: +24V to Isolated, +24V Output In Figure 6, the MAX25256 is used with a 1:1 transformer and a 4-diode bridge rectifier network (see Figure 3C) to supply +24V. Figure 6. +24V to Isolated, +24V Output Example 2: +24V to Isolated, +15V and -4V Output In Figure 7, the MAX25256 is used with a 6:4:1 center-tapped transformer and a 4-diode bridge rectifier network (see Figure 3C) to supply +15V and -4V outputs. www.maximintegrated.com Maxim Integrated | 12 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Figure 7. +24V to Isolated, +15V and -4V Output PCB Layout Guidelines As with all power-supply circuits, careful PCB layout is important to achieve low switching losses and stable operation. For thermal performance, connect the exposed pad to a solid copper ground plane. The traces from ST1 and ST2 to the transformer must be low-resistance and low-inductance paths. Place the transformer as close as possible to the MAX25256 using short, wide traces. When the device is operating with the internal oscillator, it is possible for highfrequency switching components on ST1 and ST2 to couple into the CLK circuitry through PCB parasitic capacitance. This capacitive coupling can induce duty-cycle errors in the oscillator, resulting in a direct current through the transformer. To ensure proper operation, ensure that CLK has a solid ground connection. Exposed Pad Ensure that the exposed pad has a solid connection to the ground plane for best thermal performance. Failure to provide a low thermal impedance path to the ground plane results in excessive junction temperatures when delivering maximum output power. Component Selection Input Bypass Capacitor Bypass the supply pin to GND with a 1µF ceramic capacitor as close as possible to the device. The equivalent series resistance (ESR) of the input capacitors is not as critical as for the output filter capacitors. Typically, ceramic X7R capacitors are adequate. Output Filter Capacitor In most applications, the actual capacitance rating of the output filter capacitors is less critical than the capacitor’s ESR. In applications sensitive to output-voltage ripple, the output filter capacitor must have low ESR. For optimal performance, the capacitance should meet or exceed the specified value over the entire operating temperature range. Capacitor ESR typically rises at low temperatures; however, OS-CON capacitors can be used at temperatures below 0°C to help reduce output-voltage ripple in sensitive applications. In applications where low output-voltage ripple is not critical, standard ceramic 0.1µF capacitors are sufficient. www.maximintegrated.com Maxim Integrated | 13 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Diode Selection The high switching speed of the MAX25256 necessitates high-speed rectifiers. Ordinary silicon signal diodes such as 1N914 or 1N4148 can be used for low output-current levels (less than 50mA.) But at higher output-current levels, their reverse recovery times might degrade efficiency. At higher output currents, select low forward-voltage Schottky diodes to improve efficiency. Ensure that the average forward-current rating for the rectifier diodes exceeds the maximum load current of the circuit. For surface-mount applications, Schottky diodes such as the BYS10-45HE3_A/H, MBRS140, and MBRS340 are recommended. Transformer Selection Transformer selection for the MAX25256 can be simplified by use of the ET product design metric. The ET product relates the maximum allowable magnetic flux density in a transformer core to the voltage across a winding and switching period. Inductor magnetizing current in the primary winding changes linearly with time during the switching period of the device. Transformer manufacturers specify a minimum ET product for each transformer. The transformer’s ET product must be larger than 𝐸𝑇 = 𝑉𝐷𝐷 ⁄(2 × 𝑓𝑆𝑊 ) where fSW is the minimum switching frequency of the ST1/ST2 outputs (255kHz (min)) when the internal oscillator is used, or one-half of the clock frequency when an external clock source is used. Choose a transformer with sufficient ET product in the primary winding to ensure that the transformer does not saturate during operation. Saturation of the magnetic core results in significantly reduced inductance of the primary, and therefore a large increase in the current flow. This can cause the current limit to be reached even when the load is not high. For example, when the internal oscillator is used to drive the H-bridge, the required transformer ET product for an application with VDD(MAX) = 36V is 70.6Vµs. An application with VDD(MAX) = 8.8V has a transformer ET product requirement of 17.3Vµs. In addition to the constraint on ET product, choose a transformer with a low DC-winding resistance. Power dissipation of the transformer due to the copper loss is approximated as follows: 𝑃𝐷_𝑇𝑋 = 𝐼𝐿𝑂𝐴𝐷 2 × (𝑅𝑃𝑅𝐼 ⁄𝑁 2 + 𝑅𝑆𝐸𝐶 ) where RPRI is the DC winding resistance of the primary, and RSEC is the DC winding resistance of the secondary. In most cases, an optimum is reached when RSEC = RPRI/N2. For this condition, the power dissipation is equal for the primary and secondary windings. As with all power-supply designs, it is important to optimize efficiency. In designs incorporating small transformers, the possibility of thermal runaway makes low transformer efficiencies problematic. Transformer losses produce a temperature rise that reduces the efficiency of the transformer. The lower efficiency, in turn, produces an even larger temperature rise. To ensure that the transformer meets these requirements under all operating conditions, the design should focus on the worst-case conditions. The most stringent demands on ET product arise for minimum input voltage, switching frequency, and maximum temperature and load current. Additionally, the worst-case values for transformer and rectifier losses should be considered. The primary should be a single winding; however, the secondary can be center tapped, depending on the desired rectifier topology. In most applications, the phasing between primary and secondary windings is not significant. Half-wave rectification architectures are possible with the MAX25256; however, these are discouraged. If a net DC results due to an imbalanced load, the average magnetic flux in the core is increased. This reduces the effective ET product and can lead to saturation of the transformer core. Transformers for use with the device are typically wound on a high-permeability magnetic core. To minimize radiated electromagnetic emissions, select a toroid, pot core, E/I/U core, or equivalent. A list of recommended transformers can be found in the table below: www.maximintegrated.com Maxim Integrated | 14 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies MANUFACTURER P/N TURNS RATIO MANUFACTURER WEBSITE Pulse PM2190.011NL 1:1 https://www.pulseelectronics.com/ Pulse PM2190.123NL 6:4:1 https://www.pulseelectronics.com/ Halo TGMR-511V6LF 1:1 https://www.haloelectronics.com/ Low-Voltage Operation The MAX25256 can be operated from a +8V supply by decreasing the turns ratio of the transformer, or by designing a voltage doubler circuit as shown in Figure 3B. Optimum performance at +8V is obtained with fewer turns on the primary winding since the ET product requirement is lower than for a +24V supply. However, any of the transformers for use with a +24V supply can operate properly with a +8V supply. For a given power level, the transformer currents are higher with a +8V supply than with a +24V supply. Therefore, the DC resistance of the transformer windings has a larger impact on the circuit efficiency. Ordering Information PART NUMBER TEMP RANGE PIN-PACKAGE MAX25256ATBA/V+ -40°C to +125°C T1033+1C +Denotes a lead(Pb)-free/RoHS-compliant package. -Denotes a package containing lead(Pb). /V denotes an automotive qualified part. Devices are also available in a lead(Pb)-free/RoHS-compliant package. Specify lead-free by adding “+” to the part number when ordering. Devices are also available in tape-and-reel packaging. Specify tape and reel by adding “T” to the part number when ordering. www.maximintegrated.com Maxim Integrated | 15 MAX25256 Automotive, 36V H-Bridge Transformer Driver for Isolated Supplies Revision History REVISION NUMBER 0 REVISION DATE 04/21 DESCRIPTION Initial release PAGES CHANGED — For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. 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