ADP1043A datasheet(22/72 Pages) AD

22 / 72 page

ADP1043A

Rev. 0 | Page 22 of 72

POWER SUPPLY SYSTEM AND FAULT MONITORING

The ADP1043A has extensive system and fault monitoring

capabilities. The system monitoring functions include voltage,

current, power, and temperature readings. The fault conditions

include out-of-limit values for current, voltage, power, and tem-

perature. The limits for the fault conditions are programmable.

The ADP1043A has an extensive set of flags that are set when

certain thresholds or limits are exceeded. These thresholds and

limits are described in the Fault Registers section.

FLAGS

The ADP1043A has an extensive set of flags that are set when

certain limits, conditions, and thresholds are exceeded. The

real-time status of these flags can be read in Register 0x00 to

programmable. Flags can be ignored or used to trigger tasks

such as turning off certain PWM outputs or the OrFET GATE

output. Flags can also be used to turn off the power supply. The

ADP1043A can be programmed to respond when these flags are

reset. For more information, see Register 0x08 to Register 0x0D.

The ADP1043A also has a set of latched fault registers

(Register 0x04 to Register 0x07). The latched fault registers

have the same flags as Register 0x00 to Register 0x03, but the

flags in the latched registers remain set so that intermittent

faults can be detected. Reading a latched register resets all the

flags in that register.

MONITORING FUNCTIONS

The ADP1043A monitors and reports several signals, including

voltages, currents, power, and temperature. All these values are

stored in individual registers and can be read through the I2C

interface. See the Value Registers section for more details.

VOLTAGE READINGS

The VS1, VS2, and VS3 ADCs have an input range of 1.55 V.

The outputs of the ADCs are 12-bit values, which means that

the LSB size is 1.55 V/4096 = 378.4 μV. The user is limited to an

input range of 1.5 V, which means that the ADC output code is

limited to 1.5 V/378.4 μV = 3964.

The equation to calculate the ADC code at a certain voltage

(Vx) is given by the following formula:

ADC Code

= Vx/378.4 μV

For example, when there is 1 V on the input of the ADC

ADC Code

= 1 V/378.4 μV

ADC Code

= 2643

In a 12 V application, the 12 V reading is divided down using

a resistor divider network to provide 1 V at the sense pin.

Therefore, to convert the register value to a real voltage, use

the following formula:

VOUT

= (VSx_Voltage_Value/2643) × ((R1 + R2)/R2)

In a 12 V system, this equates to

VOUT

= (VSx_Voltage_Value/2643) × 12 V

CURRENT READINGS

CS1 Pin

DC Input Voltage

The CS1 ADC is identical in design to the VS1, VS2, and VS3

ADCs. Therefore, the description in the Voltage Readings section

also applies to the CS1 ADC. When there is exactly 1 V on the

CS1 pin, the value in the CS1 value register (Register 0x13)

CS1 has an input range of 1.38 V. The ADC performs a 12-bit

reading conversion on this value, which means that the LSB size

is 1.38 V/4096 = 337 μV.

The equation to calculate the ADC code at a certain CS1 input

voltage (Vx) is given by the following formula:

ADC Code

= Vx/337 μV

For example, when there is 1 V on the CS1 input pin

ADC Code

= 1 V/337 μV

ADC Code

= 2968

AC Input Voltage

CS1 often receives a rectified ac signal through a current

transformer. In this case, the ADC has a frequency response

(see Figure 27).

105

103

101

10k

100k

CS1 INPUT FREQUENCY (Hz)

Figure 27. CS1 ADC Frequency Response

To compensate for this frequency response, the multiplication

factor (M) should be used, as shown in the following equation:

= (−2 × 10−18 × fSW3) + (2 × 10−12 × fSW2) + (2 × 10−8 × fSW) + 0.9998

where fSW is the switching frequency of the power supply.

Using the multiplication factor (M) results in a more accurate

reading. This formula can be used by an MCU or other system

monitoring device. The ADP1043A GUI has the option to use

this formula.

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