User's Manual

Confidential
INTERFACE DESCRIPT
26(31)
Document number Revision
1/155 19-KRD 104 1025 Uen PA4
5.3 Data Communication and Control Interfaces
The serial data and control interfaces consist of the following :
• USB
• P_EN
5.3.1 USB Interface
Function: USB data communication port
Description: USB transmit and receive port for data communication between
modem and host.
Pin Numbers: 1, 2
Signal Names: USB_DP (2) [modem⇔host]
USB_DN (1) [modem⇔host]
If not used: Required
Details:
The USB interface is designed to USB 1.1 specifications. Details of the specific function
of the USB interface can be found in section 6.3.
Power to the USB interface is provided by the 3V3 input from the host.
5.3.2 P_EN
Function: Power Enable
Description: Modem power enable control from host
Pin Numbers: 24
Signal Names: P_EN [host⇒daughter card]
If not used: Required
Details:
The power enable signal is provided from the host application and is routed to the
switching regulator shutdown input and also to the REG_EN (regulator enable) pin on the
modem. Assertion of this pin will initiate power up. The P_EN pin is active high and has
to be maintained continually in order to keep the modem powered.