71M6531F-IM/F Maxim Integrated Products, 71M6531F-IM/F Datasheet - Page 69

• Manufacturer Part Number: 71M6531F-IM/F
• Description: IC ENERGY METER 256KB 68-QFN
• Manufacturer: Maxim Integrated Products

Specifications of 71M6531F-IM/F

• Mounting Style: SMD/SMT
• Package / Case: QFN-68
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

FDS 6531/6532 005
3.11
Even though a functional meter will not necessarily need a reset switch, it is useful to have a reset push-
button for prototyping as shown in
(functional in MISSION mode only), V3P3D (MISSION and BROWNOUT modes), or VBAT (all modes, if
a battery is present), or from a combination of these sources, depending on the application.
For a production meter, the RESET pin should be protected by the by the external components shown in
Figure
3.12
Even when the emulator is not used, small shunt capacitors to ground (22 pF) should be used for protection
from EMI as illustrated in
3.13
It is important that a valid voltage is connected to the VBAT pin at all times. For meters without a battery,
VBAT should be connected directly to V3P3SYS. Designs for meters with batteries need to ensure that
the meter functions even when the battery voltage decreases below the specified voltage for VBAT. This
can be achieved by connecting a diode from V3P3SYS to VBAT. However, the battery test will yield
inaccurate results if that technique is used, since the voltage at V3P3SYS will feed current to the VBAT
pin. A better solution is shown in Figure 40: During the battery test, a DIO pin is activated as an output
and applies a low voltage to the anode of the diode. This prevents the voltage at the power supply to in-
fluence the voltage at the VBAT pin.
v1.3
Figure 38: External Components for the RESET Pin: Push-button (Left), Production Circuit (Right)
V3P3D
VBAT/
Since the 71M6531 generates its own power-on reset, a reset button or circuitry, as shown in
is only required for test units and prototypes.
38, right side. R1 should be in the range of 100 Ω and mounted as closely as possible to the IC.
Connecting the Reset Pin
Connecting the Emulator Port Pins
Connecting a Battery
1k Ω
R
2
0.1µF
Switch
Reset
Figure 39: External Components for the Emulator Interface
62 Ω
© 2005-2010 TERIDIAN Semiconductor Corporation
Figure
62 Ω
V3P3D
62 Ω
39. Production boards should have the ICE_E pin connected to ground.
Figure
V3P3D
R
22 pF
10k Ω
1
LCD Segments
22 pF
38, left side. The RESET signal may be sourced from V3P3SYS
(optional)
71M6531D/F
71M6532D/F
RESET
GNDD
22 pF
71M6531D/F
71M6532D/F
ICE_E
E_RST
E_RXT
E_TCLK
Data Sheet 71M6531D/F-71M6532D/F
R
R
100Ω
100Ω
1
1
71M6531D/F
71M6532D/F
RESET
RESET
DGND
DGND
71M6533
71M6533
Figure
38,
69