Data Sheet 71M6531D/F-71M6532D/F
FDS 6531/6532 005
Power
Supply
V3P3SYS
V3P3A
DIO
VBAT
+
Batteryor
Super-Cap
-
71M6531/71M6532
Figure 40: Connecting a Battery
As mentioned in section 2.3, meters equipped with batteries need to contain code that transitions
the chip to SLEEP mode as soon as the battery is attached in production. Otherwise, remaining
in BROWNOUT mode would add unnecessary drain to the battery.
3.14 Flash Programming
Operational or test code can be programmed into the flash memory using either an in-circuit emulator or
the Flash Programmer Module (TFP2) available from Teridian. The flash programming procedure uses
the E_RST, E_RXTX and E_TCLK pins. The FL_BANK[2:0] register must be set to the value corresponding
to the bank that is being programmed.
3.15 MPU Firmware
All application-specific MPU functions mentioned in the Application Information section are featured in the
demonstration source code supplied by Teridian. The code is available as part of the Demonstration Kit
for the 71M6531D/F and 71M6532D/F. The Demonstration Kits come with the 71M6531D/F or 71M6532D/F
preprogrammed with demo firmware and mounted on a functional sample meter Demo Board. The Demo
Boards allow for quick and efficient evaluation of the IC without having to write firmware or having to
supply an in-circuit emulator (ICE).
3.16 Crystal Oscillator
The oscillator drives a standard 32.768 kHz watch crystal. The oscillator has been designed specifically
to handle these crystals and is compatible with their high impedance and limited power handling capability.
The oscillator power dissipation is very low to maximize the lifetime of any battery backup device attached
to VBAT.
Board layouts with minimum capacitance from XIN to XOUT will require less battery current. Good
layouts will have XIN and XOUT shielded from each other.
For best rejection of electromagnetic interference, connect the crystal body and the ground
terminals of the two crystal capacitors to GNDD through a ferrite bead. No external resistor
should be connected across the crystal, since the oscillator is self-biasing.
70
© 2005-2010 TERIDIAN Semiconductor Corporation
v1.3
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
