CS5467 datasheet(20/46 Pages) CIRRUS

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CS5467

DS714A1

ADVANCE RELEASE

rent registers. The maximum pulse frequency from the

E1 pin is (MCLK/K)/2048.

5.5.4 Voltage Channel Sign Mode

Setting bits E3MODE[1:0] = 2 (10b) in the Operational

Mode Register

outputs the sign of the voltage channel

on pin E3. Figure 8 illustrates the output format with volt-

age channel sign on E3

Output pin E3 is high when the line voltage is positive

and pin E3 is low when the line voltage is negative.

5.5.5 PFMON Output Mode

Setting bit E3MODE[1:0] = 1 (01b) in the Operational

Mode Register

outputs the state of the PFMON compar-

ator on pin E3. Figure 9 illustrates the output format with

PFMON on E3

When PFMON is greater than the threshold, pin E3 is

high and when PFMON is less than the threshold pin E3

is low.

5.6 Sag and Fault Detect Feature

Status bit VSAG (V2SAG) and IFAULT (I2FAULT) in the

Status Register,

indicates a sag occurred in the power

line voltage (voltage 2) and current (current 2), respec-

tively. For a sag condition to be identified, the absolute

value of the instantaneous voltage or current must be

less than the sag level for more than half of the sag du-

ration (see Figure 10).

To activate voltage sag detection, a voltage sag level

must be specified in the Voltage Sag Level Register

(VSAGlevel, V2SAGlevel), and a voltage sag duration

must be specified in the Voltage Sag Duration Register

(VSAGduration, V2SAGduration). To activate current fault

detection, a current sag level must be specified in the

Current Fault Level Register

(ISAGlevel, I2SAGlevel), and

a current sag duration must be specified in the Current

Fault Duration Register

(ISAGduration, I2SAGduration).

The voltage and current sag levels are specified as the

average of the absolute instantaneous voltage and cur-

rent, respectively. Voltage and current sag duration is

specified in terms of ADC cycles.

5.7 On-chip Temperature Sensor

The on-chip temperature sensor is designed to assist in

characterizing the measurement element over a desired

temperature range. Once a temperature characteriza-

tion is performed, the temperature sensor can be uti-

lized to assist in compensating for temperature drift.

Temperature measurements are performed when a one

is written to the Temperature Measurement (Tmeas) reg-

ister and stored in the Temperature Register. The Tem-

perature Register

(T) default is Celsius scale (°C). The

Temperature Gain Register

(Tgain) and Temperature

Offset Register

(Toff) are constant values allowing for

temperature scale conversions.

The temperature update rate is a function of the number

of ADC samples. With MCLK = 4.096 MHz and K = 1

the update rate is:

The Cycle Count Register (N) must be set to a value

greater than one. Status bit TUP in the Status Register,

indicates when the Temperature Register is updated.

The Temperature Offset Register sets the zero-degree

measurement. To improve temperature measurement

accuracy, the zero-degree offset may need to be adjust-

ed after the CS5467 is initialized. Temperature-offset

calibration is achieved by adjusting the Temperature

Offset Register

(Toff) by the differential temperature

(

∆T) measured from a calibrated digital thermometer

and the CS5467 temperature sensor. A one-degree ad-

justment to the Temperature Register (T) is achieved by

Figure 8. Voltage Channel Sign Pulse outputs

Above PFMON Threshold

Below PFMON Threshold

Figure 9. PFMON output to pin E3

Level

Duration

Figure 10. Sag and Fault Detect

2240 samples

MCLK K

⁄

() 1024

⁄

----------------------------------------

0.56 sec

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