71M6521BE Datasheet, PDF (66/97 Pages) Teridian Semiconductor Corporation – Energy Meter IC

VBAT/
V3P3D
R₂
1kΩ
Reset
Switch
1nF
V3P3D
71M6521
10kΩ
R₁
RESET
DGND
71M6521BE
Energy Meter IC
DATA SHEET
JANUARY 2008
71M6521
100Ω
R₁
RESET
DGND
Figure 36: External Components for the RESET Pin: Push-Button (Left), EMI Circuit (Right)
Connecting the Emulator Port Pins
Capacitors to ground must be used for protection from EMI. Production boards should have the ICE_E pin connected to
ground.
If the ICE pins are used to drive LCD segments, the pull-up resistors should be omitted, as shown in Figure 37, and 22pF
capacitors to GNDD should be used for protection from EMI.
It is important to bring out the ICE_E pin to the programming interface in order to create a way for reprogramming
parts that have the flash SECURE bit (SFR 0xB2[6]) set. Providing access to ICE_E ensures that the part can be reset
between erase and program cycles, which will enable programming devices to reprogram the part. The reset required is im-
plemented with a watchdog timer reset (i.e. the hardware WDT must be enabled).
V3P3D
LCD Segments
(optional)
62Ω
62Ω
62Ω
22pF 22pF
71M6521B
ICE_E
E_RST
E_RXTX
E_TCLK
Figure 37: External Components for the Emulator Interface
Page: 66 of 97
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