Features and Benefits
- Controls supply voltages from 16 V to 80 V (absolute maximum 120 V)
- High voltage (80 V) IPC-9592 compliant packaging
- <500 ns response time to short circuit
- FET energy monitoring for adaptable FET SOA protection
- Gate boost mode for fast recovery from OC transients
- Programmable random start mode to stagger power-on
- FET fault detection
- Remote temperature sensing with programmable warning and shutdown thresholds
- Programmable 2.5 mV to 30 mV system current-limit setting range
- ±0.85% accurate current measurement with 12-bit ADC
- ILOAD, VIN, VOUT, temperature, power, and energy telemetry
- Programmable start-up current limit
- Programmable linear output voltage soft start
- 1% accurate UV and OV thresholds
- Programmable hot swap restart function
- 2 programmable GPIO pins
- Reports power and energy consumption
- Peak detect registers for current, voltage, and power
- PMBus fast mode compliant interface
- 48-lead 7 mm × 8 mm LFCSP
The ADM1272 is a hot swap controller that allows a circuit board to be removed from or inserted into a live backplane. It also features current, voltage, and power readback via an integrated 12-bit analog-to-digital converter (ADC), accessed using a PMBus™ interface. This device is able to withstand up to 120 V, which makes it very robust in surviving surges and transients commonly associated with high voltage systems, usually clamped using protection devices such as transient voltage suppressors (TVSs) that can often exceed 100 V.
The load current, ILOAD, is measured using an internal current sense amplifier that measures the voltage across a sense resistor in the power path via the SENSE+ and SENSE− pins. A default current limit sense voltage of 30 mV is set, but this limit can be adjusted down, if required, using a resistor divider network from the VCAP regulator output voltage to the ISET pin. An additional resistor can also be placed from ISET to VIN (or VOUT) to allow the current limit to track inversely with the rail voltage. This resistor allows an approximate system power limit to be used.
The ADM1272 limits the current through the sense resistor by controlling the gate voltage of an external N channel field effect transistor (FET) in the power path. The sense voltage, and therefore the load current, is maintained below the preset maximum. The ADM1272 protects the external FET by monitoring and limiting the energy transfer through the FET while the current is being controlled. This energy limit is set by the choice of components connected to the EFAULT pin (for fault protection mode) and the ESTART pin during startup. Therefore, different energy limits can be set for start-up and normal fault conditions. During startup, inrush currents are maintained very low and different areas of the safe operating area (SOA) curve are of interest, whereas during fault conditions, the currents can be much higher.
The controller uses the drain to source voltage (VDS) across the FET to set the current profile of the EFAULT and ESTART pins and, therefore, the amount of much energy allowed to be transferred in the FET. This energy limit ensures the MOSFET remains within the SOA limits. Optionally, use a capacitor on the DVDT pin to set the output voltage ramp rate, if required. In case of a short-circuit event, a fast internal overcurrent detector responds in hundreds of ns and signals the gate to shut down. A 1.5 A pull-down device ensures a fast FET response. The gate then recovers control within 50 µs to ensure minimal disruption during conditions, such as line steps and surges. The ADM1272 features overvoltage (OV) and undervoltage (UV) protection, programmed using external resistor dividers on the UVH, UVL, and OV pins. The use of two pins for undervoltage allows independent accurate rising and falling thresholds. The PWRGD output pin signals when the output voltage is valid and the gate is sufficiently enhanced. The validity of VOUT is determined using the PWGIN pin.
The 12-bit ADC measures the voltage across the sense resistor, the supply voltage on the SENSE+ pin, the output voltage, and the temperature using an external NPN/PNP device. A PMBus interface allows a controller to read data from the ADC. As many as 16 unique I2C addresses can be selected, depending on how the two ADRx pins are connected. The ADM1272 is available in a custom 48-lead LFCSP (7 mm × 8 mm) with a pinstrap mode that allows the device to be configured for automatic retry or latchoff when an overcurrent (OC) fault occurs.
- 48 V/54 V systems
- Power monitoring and control/power budgeting
- Central office equipment
- Telecommunication and data communication equipment
- Industrial applications
Markets and Technologies
Product Lifecycle Not Recommended for New Designs
This designates products ADI does not recommend broadly for new designs.
Evaluation Kits (1)
The EVAL-ADM1272EBZ is a compact, full featured evaluation board for the ADM1272. The board layout provides a clear visual of all the peripheral components and the hot swap power path. The layout also maximizes the ability of the board to dissipate heat for some of the key components on the power path, allowing the evaluation of high current hot swap setups.
Two sense-resistor slots and four (two on the bottom side) multipackage FET slots provide great flexibility and allow a wide range of application setups.
Multiple test points allow easy access to all critical points and pins. Six LEDs provide direct visual indication on variations in the board status, such as supply input, output, GPIO1, GPIO2, power good, and fault.
The kit supports PMBus™ communication, allowing users to communicate with the ADM1272. The evaluation kit also supports cascade setup so that multiple evaluation boards can be connected together and share the same PMBus.
The boards are fully compatible with the ADM1272 evaluation software, which can be downloaded from the ADM1272 product page.
A USB-to-I2C dongle (USB-SDP-CABLEZ) is required to use the evaluation software.
The standard evaluation kit is prepopulated and tested with a 48 V, 30 A hot swap design capable of working with a 1 mF output capacitor.
Complete specifications for the ADM1272 are available in the ADM1272 data sheet, which must be consulted in conjunction with user guide (UG-990) when using the evaluation board.
Features & Benefits
- Fully functional support evaluation kit for the ADM1272
- Populated and tested with 48 V, 30 A, 1 mF design
- 40 V undervoltage and 60 V overvoltage settings
- Custom N-MOSFET footprint suits different packages
- Supports up to 2 sense resistors in parallel
- Supports up to 4 FETs in parallel
- LED indicated status outputs
- Wide input voltage range 16 V to 80 V
- 120 V absolute maximum
- FET temperature measurement capability
- Supports cascade setup for multiple boards
- Toggle and push-button switch for easy input control
- PMBus (I2C) communication supported
Software & Systems Requirements
Hot-Swap & Power Monitoring Evaluation Software
ADMxxxx Common Run-Time
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
Models for the following parts are available in LTspice:
Microsoft Excel download tool to walk through your hotswap design using the ADM1272. Includes instructions on how to configure each function and calculate the necessary circuit values.
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.