LTM4673Y

The LTM4673Y is a quad-output step-down μModule regulator with digital power system management from Analog Devices. As part of ADI’s LTM46xx family of μModule (power module) regulators, the LTM4673 integrates the switching controllers, power MOSFETs, inductors, and support components into a single compact BGA package. What distinguishes the LTM4673 is its PMBus digital interface, enabling full digital control and monitoring of all four output rails.

Each of the four channels provides up to 5A of output current with independently programmable output voltages from 0.6V to 5.5V. The 4.5V to 17V input range covers typical 5V, 12V, and intermediate bus architectures. Synchronous rectification achieves high efficiency up to 92%, reducing thermal requirements and improving energy efficiency.

The PMBus interface is the key feature of the LTM4673, enabling digital power system management (DPSM). Through the PMBus, designers can program output voltages, set overvoltage/undervoltage/overcurrent fault thresholds, configure power-up sequencing and soft-start, and read telemetry data including input voltage, output voltage, output current, and die temperature for each channel. This enables sophisticated power management, margining for system testing, and real-time monitoring for predictive maintenance.

The LTM4673Y is supplied in a 144-ball BGA package measuring 15mm × 9mm × 3.42mm. The package includes both the controller IC and four shielded inductors, providing high power density. The device supports frequency synchronization, allowing multiple modules to be synchronized to reduce system noise. All parameters can be configured via PMBus or pin-strapped resistors for default operation without software.

The LTM4673 is a quad-channel synchronous buck μModule with PMBus digital control:

1. Four Independent Buck Converters: Each of the four channels is a complete synchronous buck converter with its own controller, power MOSFETs (high-side and low-side), and integrated shielded inductor. Each channel can be independently configured for different output voltages and current limits.

2. PMBus Interface: An I²C-compatible PMBus serial interface provides digital access to all control and monitoring functions. The PMBus address is set via pin-strapping (ADDR_SEL pin), allowing multiple modules on the same bus. The interface supports standard PMBus commands for voltage setting, fault configuration, status reading, and telemetry.

3. Voltage Mode Control: Each channel uses voltage-mode control with Type III compensation optimized for the integrated inductor and typical output capacitance. The switching frequency is 500kHz default and can be synchronized to an external clock between 500kHz and 1MHz for multi-module interleaved operation.

4. Digital Telemetry: An integrated 12-bit ADC measures input voltage, each output voltage, each output current (via DCR sensing), and die temperature. These measurements are available through PMBus read commands, enabling real-time monitoring of the power system health.

5. Output Voltage Programming: Output voltages are programmed either via PMBus (VOUT_COMMAND) or through external feedback resistors for default startup values. The PMBus can override the resistor-programmed voltage during operation, enabling dynamic voltage scaling (DVS) or margining.

6. Fault Management: Each channel has programmable overvoltage (OV), undervoltage (UV), and overcurrent (OC) fault thresholds. Fault response (latch-off, retry, ignore) is also programmable via PMBus. A fault log records fault events for diagnostic purposes.

7. Sequencing and Soft-Start: Power-up and power-down sequencing can be programmed via PMBus, with each channel assigned a turn-on delay and ramp time. This enables precise power sequencing for FPGAs, ASICs, and processors that require specific power-up order. Soft-start limits inrush current during startup.

Note: Exact BGA ball layout should be referenced from the LTM4673 datasheet. This table summarizes functional groups. The BGA-144 package has a 1.0mm ball pitch.

• Server motherboard and blade server power supplies
• Multi-rail FPGA and ASIC core power with digital management
• Telecom line cards and network processor power
• Data storage and SSD array power systems
• Industrial automation and test equipment with power monitoring
• Any system requiring power telemetry and digital power management