Dual 9A, Step-Down µModule Regulator with Digital Power System Management Design Note 542 Jian Li, Yingyi Yan and Marvin Macairan CINL 220µF CINH 22µF ×3 10k ×9 SMBus INTERFACE WITH PMBus COMMAND SET ON/OFF CONTROL, FAULT MANAGEMENT, POWER SEQUENCING PWM CLOCK SYNCH. TIME BASE SYNCH. • SLAVE ADDRESS = 1001111_R/W (0X4F) • SWITCHING FREQUENCY: 500kHz • NO GUI CONFIGURATION AND NO PART SPECIFIC PROGRAMMING REQUIRED IN MULTI-MODULE SYSTEMS, CONFIGURING RAIL_ADDRESS IS RECOMMENDED *FOR VIN ≤ 5V, SET: VIN_OFF < VIN_UV_WARN_LIMIT < VIN_ON < 4.3V VIN0 VIN1 SVIN The LTM4675 facilitates the design of high efficiency, high power density and high reliability solutions for telecom, datacom and storage systems, plus industrial and instrumentation power supplies. The LTM4675 is offered in a 16mm × 11.9mm × 3.51mm BGA package available with SnPb or RoHS compliant terminal finish. Dual 9A µModule Regulator with Digital Power System Management Figure 1 shows a typical LTM4675 application. The input voltage range is 5.75V to 17V, and the outputs are 1V/9A and 1.8V/9A. Figure 2 shows the efficiency L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. VOUT0 TSNS0 LTM4675 VORB0+ VOSNS0+ VOSNS0– VORB0– VORB1 VOUT1 TSNS1a TSNS1b VOUT0, 1.0V ADJUSTABLE UP TO 9A COUT0 100µF ×4 VDD33 SCL SDA ALERT RUN0 RUN1 GPIO0 GPIO1 SYNC SHARE_CLK WP VOSNS1 SGND GND + COMP0a COMP0b COMP1a COMP1b ASEL FSWPHCFG VOUT0CFG VTRIM0CFG VOUT1CFG VTRIM1CFG VIN* 5.75V TO 17V temperature, running peak values, uptime, faults and warnings. Current read back accuracy is ±2.5% at 9A load over temperature. INTVCC VDD25 SW0 SW1 Introduction The LTM4675 is a dual 9A or single 18A step-down µModule® (micromodule) DC/DC regulator featuring remote configurability and telemetry monitoring of power system management (PSM) parameters over PMBus—an open standard I2C-based digital interface protocol. Its 16mm × 11.9mm × 3.51mm BGA package includes analog control loops, precision mixed-signal circuitry, EEPROM, power MOSFETs, inductors and supporting components. It features a wide 4.5V to 17V input voltage range, and a 0.5V to 5.5V output voltage range with ±0.5% DC accuracy over temperature. LTM4675’s power outputs can be digitally adjusted, margined and powered up/down at programmable slew rates and sequencing delay times. Maximum turn-on time is 70ms. Telemetry read back parameters include VIN, IIN, VOUT, IOUT, LOAD0 VOUT1, 1.8V ADJUSTABLE UP TO 9A COUT1 100µF ×4 LOAD1 dn4jym F01 6.34k 1% ±50ppm/°C Figure 1. 9A, 1V and 9A, 1.8V Output DC/DC µModule Regulator with Serial Interface 09/15/542 for each output of the LTM4675 for a variety of output voltages vs load current. The LTM4675 can achieve high efficiency over a wide operating range, with high reliability. Figure 3 shows that the maximum case temperature is 84.1°C when the module is running with a 12V input, 1V/9A and 1.8V/9A outputs, without airflow. 95 90 EFFICIENCY (%) 85 80 75 VO = 2.5V, 650kHz VO = 1.5V, 575kHz VO = 1.0V, 500kHz VO = 3.3V, 650kHz VO = 1.8V, 650kHz VO = 1.2V, 500kHz VO = 0.9V, 425kHz 70 65 60 0 1 2 3 5 7 4 6 LOAD CURRENT (A) 8 9 dn4jym F02 Figure 2. LTM4675 Single Channel Efficiency at VIN = 12V Figure 3. Thermal Performance of LTM4675 at VIN = 12V, VOUT0 = 1V/9A, VOUT1 = 1.8V/9A, No Airflow, Tested on DC2053A. Maximum Temperature Rise = 61.1°C, TA = 23°C The LTM4675 offers internal compensation or external compensation, which can be used to optimize the transient response to load current steps over a wide operating range. The LTM4675 supports a PMBus-compliant SMBus serial interface up to 400kHz. Readable data includes input and output voltages, currents, temperatures, Data Sheet Download www.linear.com/LTM4675 Linear Technology Corporation running peak values, uptime, faults, warnings and an onboard EEPROM fault log record. Writable data and configurable parameters include output voltage, voltage sequencing and margining, digital soft-start/ stop ramp, OV/UV/OT, UVLO, frequency and phasing. The LTM4675 guarantees high accuracy telemetry read back with an integrated 16-bit ∆∑ ADC. Multi-Module Operation for High Current Applications The LTM4675 utilizes a constant frequency peak current mode control architecture, which enables cycle-by-cycle current limit and easy current sharing among phases when the channels are operated in parallel. For higher output current capability, it’s easy to parallel multiple LTM4675 modules. Furthermore, the LTM4675 can be used as a master to drive nonPSM power modules to provide much higher output current. For example, the LTM4675 can drive three LTM4630s to provide up to 125A output current. Figure 4 shows the thermal picture of this application. With 400LFM of airflow, the hot spot temperature rise is only 66.2°C. The uniform thermal distribution among the modules is due to excellent current sharing performance. Figure 4. Thermal Picture at VIN = 12V, VO = 1.0V/125A, 400LFM Airflow, Maximum Temperature Rise = 66.2°C, TA = 23°C Conclusion LTM4675 is a high efficiency and high power density µModule regulator with built-in digital power system management. With all of the features mentioned above, the LTM4675 is ideal for telecom, datacom and storage systems, industrial and instrumentation applications. For applications help, call (408) 432-1900 dn542f LT/AP 0915 111K REV A • PRINTED IN THE USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2015