Rainbow Electronics 71M6542G - Manual (Page 102)

102 © 2008–2011 Teridian Semiconductor Corporation v1.1
R
1
RESET
71M6533
DGND
100
Ω
R
1
RESET
71M6533
DGND
100
Ω
Figure 41: Connection for Optical Components
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
Figure 42 , left side. The RESET signal may be sourced from
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.
For a production meter, the RESET pin should be protected by the external components shown in
Figure 42 , right side. R1 should be in the range of 100
Ω and mounted as closely as possible to the IC.
Since the 71M6541D/F and 71M6542F generate their own power-on reset, a reset button or circuitry, as
shown in
Figure 42 , is only required for test units and prototypes.
Figure 42: External Components for the RESET Pin: Push-Button (Left), Production Circuit (Right)
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
Figure 43 . Production boards should have the ICE_E pin connected
to ground.
R
1
RESET
71M654x
GNDD
V3P3D
R
2
VBAT/
V3P3D
Reset
Switch
1k
Ω
0.1µF
10kΩ
OPT_TX
R
2
R
1
OPT_RX
71M654x
V3P3SYS
Phototransistor
LED
10 k
Ω
100 pF
V3P3SYS
71M654x
GNDD