Texas Instruments MSP50C6xx Calculator User Manual


 
Functional Description for the MSP50C614
1-8
Rounding out the MSP50C6xx periphery is a built in pulse-density-modulated
(PDM) digital-to-analog converter (DAC) with direct speaker-drive capability.
Typical connections to implement reset functionality are shown in Figure 13.
An external reset circuit is required to hold the reset pin low until the
MSP50C6xx power supply has stabilized in the specified voltage range. In
some cases, a simple reset circuit (as shown in Figure 13) can be used for
this purpose. However, this simple circuit may not be suitable for all applica-
tions. For example, if the power supply has an unpredictable rise time or has
intermittent voltage sags, the device may not initialize properly. The diode and
the switch shown in Figure 13 may be optional for some applications. The
diode provides a lower impedance path for the capacitor to discharge when
power is removed. This make the circuit more reliable when power is removed
and quickly reapplied.
Figure 13. RESET Circuit
Reset
Switch
1 µF
(20%)
Inside the
MSP50P614
MSP50C6xx
V
DD
V
SS
100 k
IN914
5 V
V
PP
To Pin 1 of Optional (Scanport)
Connector
RESET
1 k
To Pin 2 of optional (scan port) connector
IN914
(MSP50P614 only)
If it is necessary to use the software development tools to control the MSP50P614 in an application board, the 1 k resistor is
needed to allow the development tool to over drive the RESET circuit on the application board.
This Diode can be omitted (shorted) if the application does not require use of the scanport interface. See Section 7.1 regarding
scan port bond out.
Note:
This simple circuit may not be suitable for all applications. For example, if the
power supply has an unpredictable rise time or has intermittent voltage sags,
the device may not initialize properly.