User's Manual
Table Of Contents
- 1. Introduction
- 2. General Specification
- 3. Pin Definition
- 4. Physical Interfaces
- 5. Electrical Characteristic
- 6. Reference Design
- 7. Mechanical Characteristic
- 8. Recommended PCB Layout and Mounting Pattern
- 9. Recommended Reflow Profile
- 10. Ordering Information
FLC-BTM403 Series User Manual
Flaircomm Technologies Confidential
-20-
Parameter Possible Values
1200 baud (≤2%Error)
Baud Rate Minimum
9600 baud (≤1%Error)
Maximum 3M baud (≤1%Error)
Flow Control RTS/CTS or None
Parity None, Odd or Even
Number of Stop Bits 1 or 2
Bits per Byte 8
Table 7: Possible UART Settings
4.7.2 USB
There is a full speed (12M bits/s) USB interface for communicating with other compatible digital
devices. The module acts as a USB peripheral, responding to request from a master host controller,
such as a PC.
The module features an internal USB pull-up resistor. This pulls the USB_DP pin weakly high when
module is ready to enumerate. It signals to the USB master that it is a full speed (12Mbit/s) USB
device. The USB internal pull-up is implemented as a current source, and is compliant with section
7.1.5 of the USB specification v1.2. The internal pull-up pulls USB_DP high to at least 2.8V when
loaded with a 15kΩ ±5% pull-down resistor (in the hub/host) when VDD =3.1V. This presents a
Thevenin resistance to the host of at least 900Ω. Alternatively, an external 1.5kΩ pull-up resistor can
be placed between a PIO line and DP on the USB cable.
4.7.2.1 Self-Powered Mode
In self-powered mode, the module is powered from its own power supply and not from the VBUS
(5V) line of the USB cable. It draws only a small leakage current (below 0.5mA) from VBUS on the
USB cable. This is the easier mode for which to design, as the design is not limited by the power that
can be drawn from the USB hub or root port. However, it requires that VBUS be connected to
module via a resistor network (Rvb1 and Rvb2), so the module can detect when VBUS is powered
up. The module will not pull USB_DP high when VBUS is off.
Self-powered USB designs (powered from a battery or LDO) must ensure that a PIO line is allocated
for USB pull-up purposes. A 1.5KΩ 5% pull-up resistor between USB_DP and the selected PIO line
should be fitted to the design. Failure to fit this resistor may result in the design failing to be USB
compliant in self-powered mode. The internal pull-up in the module is only suitable for bus-powered
USB devices, e.g., dongles.