Data Sheet

AC4790
Datasheet
https://www.lairdconnect.com/
28
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10.7 Channel Warning
The OEM must prevent the end-user from selecting a channel not approved for use by the governing body in the country in
which this product is implemented.
11 REVISION 2.0 HARDWARE (AC4790-1000M, AC4790LR-1000M)
The Qorvo RF power amplifier (RF2173) used on old pre-revision 2.0 hardware is now EoL (End of Life) and the redesigned
revision 2.0 hardware uses a new Qorvo RF power amplifier (RF6886).
Additionally, revision 2.0 hardware has the following changes to help ease sourcing issues:
 Changed RF filters (LPF ceramic and BPF SAW) but with similar specifications.
 14.7456MHz crystal changed and body size reduction, but with similar specification.
 Passive component body size reduction
 and therefore, PCB layout changed.
Revision 2.0 hardware is form, fit, function equivalent to older pre-revision 2.0 hardware. See PCN 7B - 2022.
12 APPENDIX I: 5V TO 3.3V LEVELS
All inputs on the AC4790-200 & AC4790-1000, AC4790LR-1000 are weakly pulled high via 10k ohm resistors. The AC4790-
200 has 5 V inputs while the AC4790-1000, AC4470LR & AC4790-1x1 have 3.3 V inputs. The AC4790-200 uses an octal
buffer to drop the 5 V to the required 3.3 V level; the -1000 and -1x1 leave this to the OEM.
Some of the most common voltage conversion methods are described in the following sections.
12.1 Voltage Level Conversion IC’s
This is the easiest and most efficient method. Laird recommends the TI SN74LVC244A Octal Buffer/Driver. Inputs can be
driven from 3.3 or 5 V systems, allowing the device to be used in a mixed 3.3/5 V system.
Figure 10: 74LVC255 Integrated Circuits
12.2 Passive Resistor Voltage Divider
While a resistor voltage divider can successfully drop the 5 V to the required 3.3 V, it will draw static current all of the time.
Typically this method is only suitable for one-way 5 V to 3.3 V conversion. When choosing the resistor values, one needs to
include the radio’s internal 10kohm resistors on the input signals.