TLC32044C Datasheet, PDF (16/39 Pages) Texas Instruments – VOICE-BAND ANALOG INTERFACE CIRCUITS

TLC32044C, TLC32044E, TLC32044I, TLC32044M, TLC32045C, TLC32045I
VOICE-BAND ANALOG INTERFACE CIRCUITS
SLAS017F – MARCH 1988 – REVISED MAY 1995
test modes^†
The TLC32044 or TLC32045 can be operated in special test modes. These test modes are used by Texas
Instruments to facilitate testing of the device during manufacturing. They are not intended to be used in real
applications; however, they allow the filters in the A/D and D/A paths to be used without using the A/D and D/A
converters.
In normal operation, the nonusable (NU) terminals are left unconnected. These NU terminals are used by the
factory to speed up testing of the TLC32044 or TLC32045 analog interface circuits (AIC). When the device is
used in normal (non-test mode) operation, the NU terminal (terminal 1) has an internal pulldown to – 5 V.
Externally connecting 0 V or 5 V to terminal 1 puts the device in test-mode operation. Selecting one of the
possible test modes is accomplished by placing a particular voltage on certain terminals. A description of these
modes is provided in Table 2 and Figures 5 and 6.
Table 2. List of Test Modes
TEST
TERMINALS
5
D/A PATH TEST (TERMINAL 1 to 5 V)
A/D PATH TEST (TERMINAL 1 to 0)
TEST FUNCTION
TEST FUNCTION
The low-pass switched-capacitor filter clock is brought out to The bandpass switched-capacitor filter clock is brought out to
DR. This clock signal is normally internal.
DR. This clock signal is normally internal.
11
No change from normal operation. The EODX signal is The pulse that initiates the A/D conversion is brought out here.
brought out to EODX.
This signal is normally internal.
3
The pulse that initiates the D/A conversion is brought out here. No change from normal operation. The EODR signal is
brought out.
27 and 28
There are no test output signals provided on these terminals.
The outputs of the A/D path low-pass or bandpass filter
(depending upon control bit d2 – see AIC DX data word format
section) are brought out to these terminals. If the high-pass
section is inserted, the output will have a (sin x) / x droop. The
slope of the droop is determined by the ADC sampling
frequency, which is the high-pass section clock frequency
(see diagram of bandpass or low-pass filter test for receive
section). These outputs drive small (30-pF) loads.
15 and 16
D/A PATH LOW-PASS FILTER TEST: (WORD/BYTE) to – 5 V
TEST FUNCTION
The inputs of the D/A path low-pass filter are brought out to terminals 15 and 16. The D/A input to this filter is removed. If (sin x) / x
correction filter is inserted, the OUT + and OUT – signals have a flat response (see Figure 2). The common-mode range of these
inputs must not exceed ± 0.5 V.
† _{In the test mode, the AIC responds to the setting of WORD/BYTE to – 5 V, as if WORD/BYTE were set to 0 V. Thus, the byte mode is selected}
for communicating between DSP and AIC. Either of the path tests (D/A or A/D) can be performed simultaneously with the D/A low-pass filter test.
In this situation, WORD/BYTE must be connected to – 5 V, which initiates byte-mode communications.
16
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