Integration Guide

4117336 Rev 1.0 May 18, 2015 20
Hardware Integration Guide
Routing Constraints and
Recommendations
5.4. Interface Circuit Recommendations
The recommended interface implementation is to use open-drain non-inverting buffers with pull-ups to
the appropriate voltage reference. This allows a host processor operating at a different voltage to
communicate with the AirPrime AR7552 using the appropriate voltage levels.
The figure below is a reference circuit for a digital input signal to the AirPrime AR7552 device.
OVT
VCC
Output from
App
Input to AirPrime AR module
VCC_1V8
Vref of APP
Figure 5. AirPrime AR7552 Input Reference Circuit
The figure below is a reference circuit for a digital output signal from the AirPrime AR7552 device.
OVT
VCC
Output from
AirPrime AR moduleInput to App
Vref of APP
VCC_1V8
Figure 6. AirPrime AR7552 Output Reference Circuit
The open-drain non-inverting buffer used in the reference circuits above is the OnSemi NL17SZ07.
Tip: The NL17SZ07 is over-voltage tolerant on the inputs. It may be possible to power all the buffers
from the 1.8V reference voltage output. Review the digital output characteristics of the applications
drivers and the Input characteristics of the buffer selected to determine if this would work in your
application.
If a Digital IO signal is used bidirectional in the application then a bidirectional buffer or bidirectional
level translator is needed.
Note: The AR7552 modem is granted with a modular approval for mobile applications. During FCC/IC
testing, the antenna trace of the AirPrime AR7552 embedded module which located on the CCB are
defined in the table below.