TLV5590

2-BIT ANALOG-TO-DIGITAL CONVERTER

FOR FLEX

t PAGER CHIPSET

SLAS134B – NOVEMBER 1995 – REVISED NOVEMBER 1996

13

POST OFFICE BOX 655303

PRINCIPLES OF OPERATION

test mode 1 – switched-capacitor filter test

Test mode 1 places the output of the switched-capacitor low-pass filter directly on EXTS1. Note that the filter

output is not capable of driving an external load and, therefore, must be buffered externally at the EXTS1

terminal of the TLV5590. The BW input selects the filter cut-off frequency. The peak and valley DAC counters,

the decay counters, and the 2-bit ADC are all disabled during this test mode. Table 7 contains a terminal function

summary of this test mode.

Table 7. Test Mode 1 Selection

TEST = HIGH, CON1 = LOW, CON2 = HIGH

TEST INPUT

TERMINAL

INPUT

RESULT/MODE

BW

Low

1-kHz cutoff frequency (–3 dB)

BW

High

2-kHz cutoff frequency (–3 dB)

TEST OUTPUT

TERMINAL

OUTPUT SIGNAL

EXTS1

Switched-capacitor filter output (unbuffered)†

† The filter output must be buffered externally for testing.

test mode 2 – peak and valley DAC output test

Test mode 2 allows direct access to the peak and valley comparators and can be used for the pager system

debug. The peak and valley comparator outputs are accessible on the EXTS0 and EXTS1 terminals

respectively. The peak and valley counters are held at a constant value using the hold mode. Table 8 contains

a terminal function summary of this test mode.

Table 8. Test Mode 2 Selection

TEST = HIGH, CON1 = HIGH, CON2 = LOW

TEST OUTPUTS

TERMINAL

OUTPUT SIGNAL

EXTS1

Peak DAC voltage

EXTS2

Valley DAC voltage