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ADE7912/ADE7913

Data Sheet

Rev. 0 | Page 34 of 44

Power-Up Procedure for Systems with Multiple Devices

That Use a Single Crystal

For the polyphase energy meters shown in Figure 35, Figure 37,

and Figure 38, in which one single crystal is used, the power-up

procedure is as follows (see Figure 53):

Supply VDD to the ADE7912/ADE7913 devices. To ensure

that the Phase A ADE7912/ADE7913 (labeled ADE7912A/

ADE7913A in Figure 53) device starts functioning correctly,

the supply must reach 3.3 V − 10% in less than 23 ms from

approximately a 2.6 V level. The ADE7912A/ADE7913A

device is clocked by the 4.096 MHz crystal and starts

functioning. The other ADE7912/ADE7913 devices are not

clocked yet.

The dc-to-dc converter powers up and supplies the isolated

side of the ADE7912A/ADE7913A. The Σ-Δ modulators

become functional. This process takes approximately

100 ms to execute when the recommended capacitors on

the VDDISO, LDO, and REF pins described in Table 9 are

used. After this time, the isolated side of the

ADE7912A/ADE7913A is fully functional.

To determine when the ADE7912A/ADE7913A device is

ready to accept commands, the STATUS0 register is read

until Bit 0 (RESET_ON) is cleared to 0. This happens

approximately 20 ms after the ADE7912A/ADE7913A start

to function and indicates that the nonisolated side of the

ADE7912A/ADE7913A is fully functional using the default

settings.

Initialize the CONFIG register of the ADE7912A/ADE7913A

with Bit 0 (CLKOUT_EN) set to 1. The CLKOUT signal is

provided at the CLKOUT/DREADY pin, and the ADE7912/

ADE7913 devices on the other phases are now clocked.

Initialize EMI_CTRL, the emissions control register, of the

ADE7912A/ADE7913A.

The dc-to-dc converters of the other ADE7912/ADE7913

devices power up and supply their isolated sides. The Σ-Δ

modulators become functional. This process takes

approximately 100 ms to execute when the recommended

capacitors on the VDDISO, LDO, and REF pins described in

Table 9 are used. The isolated sides of the ADE7912/

ADE7913 devices are now fully functional.

Read the STATUS0 registers of the other ADE7912/

ADE7913 devices until Bit 0 (RESET_ON) is cleared to 0,

indicating that their nonisolated sides are fully functional

with default settings. This happens approximately 20 ms

after the clock signal is provided.

Initialize the CONFIG register of all remaining ADE7912/

ADE7913 devices. Select one ADE7912/ADE7913 device

(Phase C ADE7912/ADE7913 in Figure 35, Figure 37, and

Figure 38 examples; labeled ADE7912C/ADE7913C in

Figure 53) and connect its CLKOUT/DREADY pin to an

external interrupt I/O pin of the microcontroller. ADE7912C/

ADE7913C must have Bit 0 (CLKOUT_EN) in the CONFIG

functionality of the CLKOUT/DREADY pin.

Initialize EMI_CTRL, the emissions control register, of all

remaining ADE7912/ADE7913 devices.

10. Execute a SYNC_SNAP = 0x01 write broadcast to synchro-

nize all the ADE7912/ADE7913 devices of the meter (see

the Synchronizing Multiple ADE7912/ADE7913 Devices

sections).

11. Execute a lock = 0xCA write broadcast to protect the

configuration registers of all ADE7912/ADE7913 devices.

See the Protecting the Integrity of Configuration Registers

section.

12. Every couple of seconds, disable the protection of the

configuration registers, execute a SYNC_SNAP = 0x02

write broadcast to read the CNT_SNAPSHOT register of

every ADE7912/ADE7913, and verify if resynchronization

is necessary. Resynchronize the ADE7912/ADE7913

devices that are out of synchronization (see the

Synchronizing Multiple ADE7912/ADE7913 Devices

section) and then reenable the protection of the

configuration registers.

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