DocID026226 Rev 1

11/17

UM1748

EVALSTPM34, EVALSTPM33, EVALSTPM32 board

2.2.6

UART connection

UART peripheral also communicates to the device. In this case, all SWC1 switches should

be in ON position when the device powers up. RS232 port is isolated from the board through

Si8621 transceiver to safely connect the board to PC; in this case, J3 jumper has to be

connected. UART isolated pins are also available on J2 connector (Table 5) for MCU

connection; in this case J3 jumper has to be disconnected. If UART connection is used, a

separate 3.3 VDC has to be provided to UART section.

2.2.7

Metrology

Current sensing is performed by CT or shunt, while voltage is sensed by voltage

dividers.The EVALSTPM34 board has two currents and two voltage channels, while the

EVALSTPM33 has two currents and one voltage channel, the EVALSTPM32 has one

current and one voltage channel available. Main design parameters are listed in Table 6.

Table 5. J2 UART connector

Name

Description

1RXD

2TXD

3

+3.3 VDC

4GND

Table 6. EVALSTPM3x evaluation board parameters

Channel

Parameter

Value

Primary current

(1)

1.

For the EVALSTPM34 board only.

2.4 mV/A

2.

For the EVALSTPM32 and EVALSTPM33 board only.

0.3 mV/A

Primary voltage

(3)

3.

R1, R2 names do not refer to specific resistors on the schematic, but these names indicate voltage divider

resistors.

810000

Ω

(3)

470

Ω

4.

For the EVALSTPM34 and EVALSTPM33 board.

2.4 mV/A

(3)

810000

Ω

(3)

470

Ω

Any

41600 pulses/kWh