Motorola ASTRO XTS 5000 Detailed Service Manual page 63

Theory of Operation
: VOCON Board
The Flipper IC contains a USB transceiver, switching logic between RS232 and boot data path, One-
Wire side connector support, and several clock generators. The Flipper IC is programmed by the
Patriot IC.
ESD protection devices include zener diodes and low-capacitance ESD suppressors.
Side connector interface circuitry includes current-limiting resistors and noise-suppressing shunt
capacitors.
3.2.4.1 Flipper IC U301
See Figure 8-64, "NTN9564B VOCON Flipper Circuit," on page 8-99
following discussion.
The Flipper IC U301 is an application-specific, integrated circuit (ASIC) device designed for the XTS-
radio product line. The Flipper IC is contained in a 64-pin µBGA package with 0.8 mm pitch solder
balls. The Flipper IC is supplied with 5 volts and the processor's GPIO voltage, and it uses the
16.8 MHz clock (C307) as its master clock. The Flipper IC is programmable by the Patriot IC through
the SPI bus.
The Flipper IC supports many functions including the radio side connector interface, bi-directional
logic level translation, boot data path control, USB transceiver, One-Wire option detect support,
watchdog timer, 32 kHz oscillator with CMOS output, 13 MHz reference generation for the GCAP II
IC, and SSI clock and frame sync generator.
3.2.4.1.1 Side Connector Interface, Logic Level Translation, and Boot Data Path Control
The Flipper IC facilitates the interface to the radio's side connector. Some of the side connector lines
are at 5 V logic levels, so the Flipper IC converts those lines to GPIO voltage logic levels to interface
to the Patriot IC, as well as the encryption module. These lines include the SB9600 bus busy line
LH_BUSY (TP207), the RS 232 CTS (TP208) and RTS (TP209) lines, the RS232 data-out line
(TP210), and the RS232 data-in line (TP211). The SB9600 data line uses an external, bi-directional,
voltage translation circuit that includes Q303, D301, R325, R326, and R327.
Another function that the Flipper IC provides with these lines is boot data path control. The boot data
path is as follows: boot data-in is multiplexed onto the RS232 data-out line while the boot data-out is
multiplexed with the SB9600 data line. This alternate data path is used only to Flash code into a
radio for the first time. The Patriot IC, through the SPI bus, controls this feature.
3.2.4.1.2 USB Transceiver
The USB transceiver, internal to the Flipper IC, is capable of transmitting and receiving serial data at
a rate of 12 megabits per second. The differential USB data comes from the side connector, through
the 22-ohm resistors R252 and R253 and the isolation switch Q301, and then to the USB_DPLUS
and USB_DMINUS pins on the Flipper IC. The USB receive interface from the Flipper IC to the
Patriot IC is as follows: USB_DPLUS routed to USB_VPI, USB_DMINUS routed to USB_VMI_RXD,
and the differential decoded data is output at the URXD_RTS pin and goes to the Patriot IC URTS1
pin.
The USB transmitter is enabled when the USB_SUSP and USB_TXENAB signals are both driven
low by the Patriot IC. The single-ended data is output from the Patriot IC on the UTXD1 pin and goes
to the Flipper TXD_USB_VPO pin. The data is driven out differentially on the USB_DPLUS and
USB_DMINUS pins, which go to the side connector. The Patriot IC sends the single-ended zero
signal from pin PC0_USB_VMOUT to the Flipper IC USB_FSEZ pin.
6881094C31-D
for schematic details of the
July 21, 2004
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