Datasheet

VOUT

GND

V+

Vin-

Vin+

Current Path

Rsense

INA196

3.3V

MONx

AVSS1

UCD90124A

Gain = 20V/V

UCD90124A

SLVSAN8 –JANUARY 2012

www.ti.com

IOUT_CAL_GAIN is a PMBus command that allows the scale factor of an external current sensor and any

amplifiers or attenuators between the current sensor and the MON pin to be entered by the user in milliohms.

IOUT_CAL_OFFSET is the current that results in 0 V at the MON pin. The combination of these PMBus

commands allows current to be reported in amperes. The example below using the INA196 would require

programming IOUT_CAL_GAIN to Rsense(mΩ)×20.

Figure 11. Current Monitoring Circuit Example Using the INA196

REMOTE TEMPERATURE MONITORING AND INTERNAL TEMPERATURE SENSOR

The UCD90124A has support for internal and remote temperature sensing. The internal temperature sensor

requires no calibration and can report the device temperature via the PMBus interface. The remote temperature

sensor can report the remote temperature by using a configurable gain and offset for the type of sensor that is

used in the application such as a linear temperature sensor (LTS) connected to the analog inputs.

External circuitry must be used in order to convert the temperature to a voltage within the range of the

UCD90124A MONx input being used.

If an input is configured as a temperature, the measurements are smoothed by a sliding average digital filter. The

temperature for 1 rail is measured every 100ms. If the device is programmed to support 10 rails (independent of

temperature not being monitored at all rails), then each rail's temperature will get measured every 1s. The

temperature calculation is done with a sliding average using the last 16 measurements. The filter reduces the

probability of false fault detections, and introduces a small delay to the temperature reading. The internal device

temperature is measured using a silicon diode sensor with an accuracy of ±5°C and is also monitored using the

ADC. Temperature monitoring begins immediately after reset and initialization.

The device supports multiple PMBus commands related to temperature, including READ_TEMPERATURE_1,

which reads the internal temperature; READ_TEMPERATURE_2, which reads external temperatures; and

OT_FAULT_LIMIT and OT_WARN_LIMIT, which set the overtemperature fault and warning limit. The UCD90xxx

Sequencer and System Health Controller PMBus Command Reference contains a detailed description of how

temperature-fault responses are implemented using PMBus commands.

TEMPERATURE_CAL_GAIN is a PMBus command that allows the scale factor of an external temperature

sensor (Figure 12) and any amplifiers or attenuators between the temperature sensor and the MON pin to be

entered by the user in °C/V. TEMPERATURE_CAL_OFFSET is the temperature that results in 0 V at the MON

pin. The combination of these PMBus commands allows temperature to be reported in degrees Celsius.

Product Folder Link(s) :UCD90124A