71M6541D Maxim, 71M6541D Datasheet - Page 102

• Manufacturer Part Number: 71M6541D
• Description: The 71M6541D/71M6541F/71M6541G/71M6542F/71M6542G are Teridian™ 4th-generation single-phase metering SoCs with a 5MHz 8051-compatible MPU core, low-power RTC with digital temperature compensation, flash memory, and LCD driver
• Manufacturer: Maxim

to ground.
71M6541D/F/G and 71M6542F/G Data Sheet
If operation in BRN mode is desired, the external components should be connected to V3P3D. However,
it is recommended to limit the current to a few mA.
4.12 Connecting the Reset Pin
Even though a functional meter does not necessarily need a reset switch, it is useful to have a reset
pushbutton for prototyping as shown in
V3P3SYS (functional in MSN mode only), V3P3D (MSN and BRN modes), or VBAT (all modes, if a
battery is present), or from a combination of these sources, depending on the application.
Since the 71M6541D/F/G and 71M6542F/G generate their own power-on reset, a reset button or circuitry, as
shown in
4.13 Connecting the Emulator Port Pins
Even when the emulator is not used, small shunt capacitors to ground (22 pF) should be used for
protection from EMI as illustrated in
102
Figure 42: External Components for the RESET Pin: Push-Button (Left), Production Circuit (Right)
V3P3D
VBAT/
For a production meter, the RESET pin should be protected by the external components shown in
Figure
Figure
42, right side. R1 should be in the range of 100Ω and mounted as closely as possible to the IC.
1k Ω
42, is only required for test units and prototypes.
R
2
0.1µF
Switch
Reset
71M654x
Figure 41: Connection for Optical Components
OPT_RX
OPT_TX
R
Figure
V3P3D
10kΩ
1
Figure
100 pF
43. Production boards should have the ICE_E pin connected
42, left side. The RESET signal may be sourced from
RESET
GNDD
71M654x
10 kΩ
R
2
V3P3SYS
R
LED
Phototransistor
1
V3P3SYS
GNDD
71M654x
Rev 2