2–3

2.1.13

FIR Overflow Flag

The decimator FIR filter provides an overflow flag to the control 2 register to indicate that the input to the

filter has exceeded the range of the internal filter calculations. When this bit is set in the register, it remains

set until the register is read by the user. Reading this value always resets the overflow flag.

2.2

Terminal Descriptions

The following sections describe the terminal functions.

2.2.1

Reset and Power-Down

2.2.1.1

Reset

As shown in Figure 2–1, the TLC320AD55C resets both the internal counters and registers, including the

programmed registers, in two ways:

•

By appling a low-going reset pulse to the RESET terminal

•

By writing to the programmable software reset bit (D07 in control 1 register)

PWRDWN resets the counters only and preserves the programmed register contents. The DAC resets to

the 15-bit mode.

RESET

D

TRESET

RESET

Software RESET Control

Register 1, Bit 7

MCLK

To Circuitry

NOTE A: RESET to circuitry is at least 6 MCLK periods long and releases on the positive edge of MCLK.

Internal TLC320AD55C

Figure 2–1. Reset Function

2.2.1.2

Conditions of Reset

The two internal reset signals used for the reset and synchronization functions are:

•

Counter reset

– This signal resets all flip-flops and latches that are not externally programmed,

with the exception of those generating the reset pulse itself. Additionally, this

signal resets the software power-down bit.

Counter reset

=RESET terminal or reset bit or PWRDWN terminal

•

Register reset

– This signal resets all flip-flops and latches that are not reset by the counter

reset, except those generating the reset pulse itself.

Register reset

=RESET terminal or reset bit