CS5490-ISZR View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS5490-ISZR

Two Channel Energy Measurement IC

Cirrus Logic 

CS5490

EPG_ON

(Config1)

MCLK

PAVG

PSUM

0000

Reserved 0001

0010

Q AVG

Q SUM

0011

Reserved 0100

0101

S

SSUM

0110

Reserved 0111

1000

PULSE RATE

0000

Reserved 0001

Reserved 0010

Reserved 0011

P Sign 0100

Reserved 0101

PSUM Sign 0110

Q Sign 0111

Reserved 1000

QSUM Sign 1001

Reserved 1010

V Crossing 1011

I Crossing 1100

Reserved 1101

Hi-Z 1110

Interrupt 1111

DO_OD

(Config1)

DO

(PulseCtrl) EPGIN[3:0] 4

(PulseWidth) FREQ_RNG[3:0] 4

(PulseWidth) PW[7:0] 8

DOMODE[3:0] 4

(Config1)

Figure 10. Energy Pulse Generation and Digital Output Control

After reset, the energy pulse generation block is

disabled (DOMODE[3:0] = Hi-Z). To output a desired

energy pulse to a DO pin, it is necessary to follow the

steps below:

1. Write to register PulseWidth (page 0, address 8) to

select the energy pulse width and pulse frequency

range.

2. Write to register PulseRate (page 18, address 28) to

select the energy pulse rate.

3. Write to register PulseCtrl (page 0, address 9) to

select the input to the energy pulse generation block.

4. Write ‘1’ to bit EPG_ON of register Config1 (page 0,

address 1) to enable the energy pulse generation

block.

5. Wait at least 0.1s.

6. Write bits DOMODE[3:0] of register Config1 to select

DO to output pulses from the energy pulse

generation block.

7. Send DSP instruction (0xD5) to begin continuous

conversion.

5.5.1 Pulse Rate

Before configuring the PulseRate register, the full-scale

pulse rate needs to be calculated, and the frequency

range needs to be specified through FREQ_RNG[3:0]

bits in the PulseWidth register. For example, if a meter

has the meter constant of 1000imp/kWh, a maximum

voltage (UMAX) of 240V, and a maximum current (IMAX)

of 100A, the maximum pulse rate is:

[1000x(240x100/1000)]/3600 = 6.6667Hz.

Assume the meter is calibrated with UMAX and IMAX,

and the Scale register contains the default value of 0.6.

After gain calibration, the power register value will be

0.36, which represents 240 x 100 = 24kW or 6.6667Hz

pulse output rate. The full-scale pulse rate is:

Fout = 6.6667/0.36 = 18.5185Hz.

Refer to section 6.6.6 Pulse Output Width (PulseWidth)

– Page 0, Address 8 on page 35. The FREQ_RNG[3:0]

bits should be set to b[0110].

20

DS982F2

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