9

TH6503 USB Low-Speed Interface

Application

Wiring Diagram

Figure 14 shows a sample Application circuitry with the TH6503 and a MC68HC05.

To stabilize the internal power supply the V3.3 pin must always be connected with an 10µ capaci-

tor.

Figure 14. Sample Wiring diagram to connect the TH6503 with an MC68HC05

WAKE Function

The USB specification defines that a device has to

go into suspend mode if no bus traffic was de-

tected for ca. 3 ms. After the device is set to

suspend mode, the WAKE pin can be used to

Wake up the device with an external event.

If the WAKE pin is connected with an RC-Element,

the TH6503 wakes up after the time defined by the

RC-Element. This feature can be used to check for

data in periodical time frames.

RESET Output

The reset output (/ORST) of the TH6503 can be

connected

with

the

reset

input

of

the

microcontroller. It’s a low active signal.

This signal has a minimum length of 31 clock

cycles with a default frequency of 1.5 MHz (see Pin

Description for details).

After this reset pulse the microcontroller can

reseted but it must wait to programming the

TH6503 until the USB reset is inactive.

All register of TH6503 will be held in reset state,

exept the StatusRegister, until the corresponding

bits HWR or RES is cleared.