Operating Modes; I 2 C Control Mode; Alc Mode; Gain Select Mode - Analog Devices SSM2380 User Manual

Evaluation Board User Guide

OPERATING MODES

The SSM2380 has three operating modes: I
ALC mode, and gain select mode. These modes are described
in detail in the SSM2380 data sheet. On the evaluation board,
the 3-pin JP11 jumper allows the user to change between the
available operating modes.
2
I C CONTROL MODE
To operate the SSM2380 in I
shown in Figure 5, connecting the MODE pin to GND. While
2
in I C control mode, JP9 and JP10 are not used and the jumpers
should be left unconnected.
Figure 5. Jumper Connections for I

ALC MODE

The proper connections for ALC mode are shown in Figure 6.
For this setting, JP11 is open and the middle and bottom pins
of JP9 are shorted. This floats the MODE pin and makes a
connection from the SSM2380
R24 to GND, setting the SSM2380
is used to activate the radiated emissions reduction mode in
this configuration.
Figure 6. Jumper Connections for ALC Mode Operation
The limiting percentage of the ALC feature is determined by the
value of an external resistor, R24, which should be placed on the
secondary side of the board. The resistor value can be calculated
using the curve shown in Figure 7.
2
C control mode,
2
C control mode, connect JP11 as
2
C Mode Operation
ALCTH pin with Resistor
ALC limiting range. JP10
95
90
85
80
75
70
65
60
TYPICAL CONDITION
55
INTERNAL RESISTOR – 20%
INTERNAL RESISTOR + 20%
50
45
100
Figure 7. Output Voltage Limit (V

GAIN SELECT MODE

The proper connections for gain select mode are shown in
Figure 8. A jumper must be inserted on JP11 from center pin
to top pin. JP9 and JP10 allow the user to select the
gain from 6 dB to 24 dB. To connect the appropriate gain select
pin to VDD, place a jumper from the center pin to the top pin
of the header. To select GND, simply move the jumper connec-
tion to the center pin and bottom pin of the header. A gain
select table shows all possible settings in Table 2. All other
features (ALC, emissions control, and mixer) are deactivated
while the SSM2380
Figure 8. Jumper Connections for Gain Select Mode Operation
Table 2. Gain Select Mode Settings for JP9 and JP10
GAIN1 (JP9)
GND
GND
VDD
VDD
Rev. 0 | Page 5 of 20
1k 10k 100k
RESISTOR (Ω)
) vs. R
TH
is in gain select mode.
GAIN0 (JP10) Gain Setting
GND 6 dB
VDD 12 dB
GND 18 dB
VDD 24 dB
UG-248
1M
TH
SSM2380