WT11i-E-AI4 Bluegiga Technologies, WT11i-E-AI4 Datasheet - Page 19

• Manufacturer Part Number: WT11i-E-AI4
• Description: Bluetooth / 802.15.1 Modules WT11i Class1 2.1+EDR uFL Conn iWRAP 4
• Manufacturer: Bluegiga Technologies

Specifications of WT11i-E-AI4

• Rohs: yes
• Class: 1
• Sensitivity: - 83 dBm
• Operating Supply Voltage: 3.3 V
• Interface Type: UART, USB
• Antenna Connector Type: Chip
• Maximum Operating Temperature: + 85 C
• Dimensions: 35.75 mm x 14.5 mm x 2.6 mm
• Mounting Style: SMD/SMT

The terminal marked USB_ON can be any free PIO pin. The PIO pin selected must be registered by setting
PSKEY_USB_PIO_VBUS to the corresponding pin number.
**) WT11i has internal 22 ohm series resistors at the USB lines.
7.5 Bus-Powered Mode
In bus-powered mode, the application circuit draws its current from the 5V VBUS supply on the USB cable.
WT11i negotiates with the PC during the USB enumeration stage about how much current it is allowed to
consume. On power-up the device must not draw more than 100 mA but after being configured it can draw up
to 500 mA.
For WT11i, the USB power descriptor should be altered to reflect the amount of power required. This is
accomplished by setting PSKEY_USB_MAX_POWER (0x2c6). This is higher than for a Class 2 application
due to the extra current drawn by the Transmit RF PA. By default for WT11i the setting is 300 mA.
When selecting a regulator, be aware that VBUS may go as low as 4.4V. The inrush current (when charging
reservoir and supply decoupling capacitors) is limited by the USB specification. See the USB Specification.
Some applications may require soft start circuitry to limit inrush current if more than 10uF is present between
VBUS and GND. The 5V VBUS line emerging from a PC is often electrically noisy. As well as regulation down
to 3.3V and 1.8V, applications should include careful filtering of the 5V line to attenuate noise that is above the
voltage regulator bandwidth. Excessive noise on WT11i supply pins will result in reduced receiver sensitivity
and a distorted RF transmit signal.
Identifier
R
R
R
S
vb1
vb2
Figure 9: USB Connections for Self-Powered Mode
Value
0 to 10 (to be matched per design)**
22k 5%
47k 5%
Figure 10: USB Interface Component Values
Bluegiga Technologies Oy
Function
Impedance matching to USB cable
VBUS ON sense divider
VBUS ON sense divider
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