Semiconductor device and liquid crystal panel driver device
View Patent ↗A semiconductor device carries out a test utilizing contact with a probe needle without being affected by narrowing of the pitch at which output pads are arranged. The device is equipped with test circuits provided between a plurality of output buffers via which signals are output and output pads corresponding thereto. The test circuit includes output switches caused to sequentially make connections by a controller in test and interpad switches involved in making connections of the output pads with a test pad by the controller in test. In test, probe needles are brought into contact with the test pad. The output pads are not used in test, and can be arranged at a narrowed pitch. Thus, the chip area can be reduced and are therefore so that the pitch for the output pads can be narrowed and the chip area can be decreased.
1. A liquid cristal driver device comprising:
a plurality of drive circuits for driving pixels of a liquid crystal panel; a plurality of output pads corresponding to the drive circuits;
a plurality of input pads used in test mode;
a test pad disposed in line with the input pads;
a plurality of output switches, one for each adjacent pair of nth and (n×1)th driver circuits, providing three operating states of: (a) connecting outputs of the nth and (n+1)th driver circuits straight to the nth and (n×1)th output pads, respectively, (b) cross-connecting the outputs of the nth and (n×1)th driver circuits to the (n×1)th and nth output pads, respectively, and (c) disconnecting the (n×1)th and nth output pads from the nth and (n×1)th driver circuits;
interpad switches connecting every other output pad to the test pad in test mode; and
a controller sequentially making connections via the output switches in the test mode, wherein the controller in the test mode causes the outputs of each adjacent pair of driver circuits to appear one by one at the test pad by setting the corresponding output switch to the operating state (a) or (b) while maintaining the other output switches in the operating state (c).