ADP1046ACPZ-R7 datasheet(28/96 Pages) AD

28 / 96 page

ADP1046

Data Sheet

Rev. 0 | Page 28 of 96

POWER READINGS

The output power value register (Register 0x19) is the product

of the VS3 voltage value and the CS2 current value. Therefore,

a combination of the formulas in the Voltage Readings section

and the CS2+, CS2− Pins section is used to calculate the power

reading in watts. This register is a 16-bit word. It multiplies two

12-bit numbers and discards the eight LSBs.

POUT = VOUT × IOUT

For example,

POUT = 12 V × 4.453 A = 53.436 W

POWER MONITORING ACCURACY

The ADP1046 power monitoring accuracy is specified relative

to the full-scale range of the signal that it is measuring.

FIRST FLAG FAULT ID AND VALUE REGISTERS

When the ADP1046 registers several fault conditions, it stores

the value of the first fault in a dedicated register. For example,

if the overtemperature (OTP) fault is registered followed by an

OVP fault, the OTP flag is stored in the first flag ID register

(Register 0x10). This register gives the user more information

for fault diagnosis than a simple flag. The contents of this register

are latched, meaning that they are stored until read by the user.

The contents are also reset by toggling PSON. If a flag is set to

be ignored, it does not appear in the first flag register.

EXTERNAL FLAG INPUT (FLAGIN PIN)

The FLAGIN pin can be used to send an external fault signal

into the ADP1046. Register 0x0A[3:0] can be used to program

the FLAGIN flag to trigger an action.

TEMPERATURE READINGS (RTD PIN)

The RTD pin is set up for use with an external negative tempera-

ture coefficient (NTC) thermistor. The RTD pin has an internal

programmable current source. An ADC monitors the voltage

on the RTD pin.

The RTD temperature value register, Register 0x1A, is updated

every 10 ms. The ADP1046 stores every ADC sample for 10 ms

and then outputs the average value at the end of the 10 ms period.

The RTD ADC has an input range of 1.6 V and a resolution of

12 bits, which means that the LSB size is 1.6 V/4096 = 390.625 μV.

The user is limited to an input range of 1.3 V, which means that the

maximum ADC output code is limited to 1.3 V/390.6 μV = 3328.

The output of the RTD ADC is linearly proportional to the vol-

tage on the RTD pin. However, thermistors exhibit a nonlinear

function of resistance vs. temperature. Therefore, the user must

perform postprocessing on the RTD ADC reading to accurately

read the temperature.

By connecting an external resistor (REXT) in parallel with the

NTC thermistor (TH), a constant current can be used to

achieve linearization (see Figure 36).

ADC

DAC

RTD

REXT

Figure 36. Temperature Measurement Using Thermistor

An internal, precision current source of 10 μA, 20 μA, 30 μA,

or 40 μA can be selected in Register 0x11. This current source

can be trimmed by means of an internal DAC to compensate

for thermistor accuracy (see the RTD/OTP Trim section). The

user can select the output current source using Bits[7:6] of

The ADP1046 implements a linearization scheme based on a

preselected combination of external components and current

selection for best performance when measuring linearized

temperatures in degrees Celsius in the industrial range.

For more information about the required thermistor and

selecting and trimming the precision current sources, see

the Temperature Linearization Scheme section.

Optionally, the user can process the RTD reading and perform

postprocessing in the form of a lookup table or polynomial

equation to match the specific NTC thermistor used. With the

internal current source set to 46 μA, the equation to calculate

the ADC code at a specified NTC thermistor value (Rx) is given

by the following formula:

ADC CODE = 46 μA × Rx/1.6 × 4096

For example, at 60°C, the NTC thermistor at the RTD pin is

21.82 kΩ.

RTD_ADC_CODE = 46 μA × 21.82 kΩ/1.6 × 4096 = 2570

FLAGS

OTP

FLAG

OTP

THRESHOLD

REG 0x2F[7:0]

RTD TEMPERATURE

VALUE REGISTER

REG 0x1A[15:4]

RTD TEMPERATURE

VALUE IN °C

REG 0x1B[7:0]

SIGNAL

CONDITIONING

10µA/20µA/30µA/40µA

RTD

100kΩ

NTC

16.5kΩ

RTD

ADC

Figure 37. RTD Pin Internal Details

ADP1046ACPZ-R7 数据表(PDF) 28 Page - Analog Devices

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