Exact function unknown, but seems to be part of a Motorola mobile handset chipset. This is likely the baseband processor. The other chip in the set is SC13890P23A.
(Logo) SC29343VKP M40B CTAG0710 CHINA
(Logo) PC29341VKPR2 DSP56640 M40B 2004
Top metal imaged under Nikon PlanApo 20x/0.75