Dual 13A μModule Regulator with Digital Interface for Remote Monitoring & Control of Power Design Note 524 Jian Li and Gina Le standard I2C-based digital serial interface protocol. The LTM4676 combines best-in-class analog switching regulator performance with precision mixed signal data acquisition. It features ±1% maximum DC output voltage error and ±2.5% current read back accuracy over temperature (TJ = –40ºC to 125ºC), and integrated 16-bit delta-sigma ADC and EEPROM. Digital Power System Management: Set, Monitor, Change and Log Power Managing power and implementing flexibility in a high rail count circuit board can be challenging, requiring hands-on probing with digital voltmeters and oscilloscopes, and often rework of PCB components. To simplify power management, especially from a remote location, there is a trend to configure and monitor power via a digital communications bus. Digital power system management (PSM) enables on-demand telemetry capability to set, monitor, change and log power parameters. The LTM4676’s 2-wire serial interface allows outputs to be margined, tuned and ramped up and down at programmable slew rates with sequencing delay times. Input and output currents and voltages, output power, temperature, uptime and peak values are readable. The device is comprised of fast, dual analog control loops, precision mixed signal circuitry, EEPROM, power MOSFETs, inductors and supporting components housed in a 16mm × 16mm × 5.01mm BGA (ball grid array) package. Dual µModule® Regulator with Precision READ/WRITE of Power Parameters The LTM®4676 is a dual 13A output constant frequency switching mode DC/DC µModule (micromodule) regulator (Figure 1). In addition to delivering power at a point-of-load, the LTM4676 features configurability and telemetry-monitoring of power and power management parameters over PMBus— an open 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: 350kHz • NO GUI CONFIGURATION AND NO PART SPECIFIC PROGRAMMING REQUIRED * FOR 4.5VIN, CONNECT INTVCC TO VIN VIN0 VIN1 SVIN VOUT0 TSNS0a TSNS0b ISNS0a+ ISNS0b+ ISNS0a– ISNS0b– VOSNS0+ VOSNS0– VDD33 SCL SDA ALERT RUN0 RUN1 GPIO0 GPIO1 SYNC SHARE_CLK WP LTM4676 22.6k 1% ±50ppm/°C VOUT1 TSNS1a TSNS1b ISNS1a+ ISNS1b+ ISNS1a– ISNS1b– VOSNS1 SGND COUT0 100µF ×7 COUT1 100µF ×7 LOAD1 6.34k 1% ±50ppm/°C Figure 1. LTM4676: Dual 13A Output µModule Regulator with PMBus Interface 03/14/524 VOUT0, 1.0V ADJUSTABLE UP TO 13A LOAD0 GND CINL 220µF INTVCC VDD25 SW0 SW1 SNUB0 SNUB1 + COMP0a COMP0b COMP1a COMP1b ASEL FSWPHCFG VOUT0CFG VTRIM0CFG VOUT1CFG VTRIM1CFG VIN 5.75V* TO 26.5V L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks and LTpowerPlay is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. VOUT1, 1.8V ADJUSTABLE UP TO 13A The LTM4676 operates from a 4.5V to 26.5V input supply and steps down VIN to two outputs ranging from 0.5V to 5.4V. Two outputs can current share to provide up to 26A (i.e., 13A + 13A as one output). Internal or External Compensation The LTM4676 offers both internal or external compensation, which can optimize the transient response over a wide operating range. Figure 2 shows that the peak-to-peak output voltage is only 94mV with a 50% load step. ing among multiple phases. Paralleling modules can achieve much higher output current capability. For example, four LTM4676 µModule regulators can be paralleled to provide up to 100A output current. Figure 3 shows the thermal picture. With 300LFM of airflow, the hot spot temperature rise is only 64.3°C. The even thermal distribution among modules is due to excellent current sharing performance. Figure 4 is a photo of the demo board with four LTM4676 µModule regulators assembled to provide 100A at 1V. VPP = 94mV VO (50mV/DIV) IO = 6.5 ~ 13A IO (5A/DIV) dn4jlgl F02 Figure 2. Transient Response of the LTM4676 in Figure 1 at VIN = 12V, VOUT1 = 1.8V, IO = 6.5A ~ 13A Figure 4. Four LTM4676, Each in a 16mm × 16mm × 5.01mm LGA Package Deliver 100A at 1VOUT. Conclusion Linear Technology’s digital power system management (PSM) products provide users with critical power-related data. One can access load current, input current, output voltages, compute power consumption, efficiency, and access other power management parameters via a digital bus. This enables predictive analytics, minimizes operating costs, increases reliability and ensures smart energy management decisions can be made. Figure 3. Four LTM4676 Current Sharing: Thermal Picture at VIN = 12V, VOUT = 1.0V/100A, 300LFM Airflow Current Share for up to 100A at 1VOUT The LTM4676 uses a constant frequency peak current mode control architecture, which offers a cycle-by-cycle current limit and easy current sharData Sheet Download www.linear.com/LTM4676 Linear Technology Corporation On-demand digital control and monitoring of system power with the LTM4676 eliminates PCB layout and circuit component manipulation and accelerates system characterization, optimization and data mining during prototyping, deployment and field operation. For demo kits, free download of the LTPowerPlay™ GUI and PSM training videos, please visit www.linear.com and type “PSM” in the SEARCH box. For applications help, call (408) 432-1900, Ext. 3578 dn524 LT/AP 0314 111K • PRINTED IN THE USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2014