AC4790-200A-485 Laird Technologies, AC4790-200A-485 Datasheet - Page 51

• Manufacturer Part Number: AC4790-200A-485
• Description: TXRX 900MHZ 3.3-5.5V FHSS 200MW
• Manufacturer: Laird Technologies
• Series: AeroCommr

Specifications of AC4790-200A-485

• Frequency: 902MHz ~ 928MHz
• Data Rate - Maximum: 115.2kbps
• Modulation Or Protocol: FHSS, FSK
• Applications: AMR, Fire & Security Alarms, Telemetry
• Power - Output: 5mW ~ 200mW
• Sensitivity: -110dBm
• Voltage - Supply: 3.3V, 5V
• Current - Transmitting: 68mA
• Data Interface: Connector, 2 x 10 Header
• Antenna Connector: On-Board, Chip
• Operating Temperature: -40°C ~ 85°C
• Package / Case: Module
• Wireless Frequency: 900 MHz
• Interface Type: 20-pin mini connector
• Board Size: 49 mm x 42 mm x 5 mm
• Modulation: FHSS, FSK
• Security: 1 byte System ID, DES
• Operating Voltage: 3.3 V to 5.5 V
• Output Power: 200 mW
• Antenna: Integral and External Dipole
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Memory Size: -
• Current - Receiving: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

A
All inputs on the AC4790-200 & AC4790-1000 are weakly pulled high via 10 kohm resistors. The AC4790-200 has 5V
inputs while the AC4790-1000 & AC4790-1x1 have 3.3V inputs. The AC4790-200 uses an octal buffer to drop the 5V to
the required 3.3V level; the -1000 and -1x1 leave this to the OEM.
Some of the most common voltage conversion methods are described below.
V O L T A G E L E V E L C O N V E R S I O N I C ’ S
This is the easiest and most efficient method. Laird Technology recommends the TI SN74LVC244A Octal
Buffer/Driver. Inputs can be driven from either 3.3 or 5V systems, allowing the device to be used in a mixed 3.3/5V
system.
P A S S I V E R E S I S T O R V O L T A G E D I V I D E R
While a resistor voltage divider can successfully drop the 5V to the required 3.3V, it will draw static current all of the
time. Typically this method is only suitable for one-way 5V to 3.3V conversion. When choosing the resistor values, one
needs to include the radio’s internal 10 kohm resistors on the input signals.
PPENDIX
II - 5V
10
1
2
3
4
5
6
7
8
9
1OE
1A0
2Y3
1A1
2Y2
1A2
2Y0
2Y1
GND
1A3
2Y0
GND
74LVC244
VCC
2OE
1Y0
2A3
1Y1
2A2
1Y3
1Y2
2A0
2A1
1Y3
2A0
20
19
18
17
16
15
14
13
12
11
TO
3.3V L
www.lairdtech.com\wireless
18
16
14
12
EVELS
Y0
Y1
Y2
Y3
74LVC244
OE
1
A0
A1
A2
A3
2
4
6
8
Input A
Input B
Input C
Input D
II