Apalis Carrier Board Design Guide
Toradex AG l Altsagenstrasse 5 l 6048 Horw l Switzerland l +41 41 500 48 00 l
l
Page | 45
2.9.2
Reference Schematics
The horizontal and vertical sync signals need to be level shifted on the baseboard. The same is true
for the DDC I
2
C signals. In the VGA connector standard, the carrier board needs to provide 5V
power supply for the EDID memory on the DDC. This allows the system to read out the EDID
information of an attached display even if it is not powered. Unfortunately, some displays source
the 5V internally and also provide internal pull-up resistors to the I
2
C lines. This can cause back-
feeding problems. Therefore, we recommend connecting the display and pull-up resistor 5V supply
over a diode to the module supply.
It is mandatory to place a 150
Ω
resistor to ground on every analogue RGB signal. Place this
resistor as close to the VGA connector as possible. Before this resistor, the signal trace can be
routed with 50
Ω
impedance. After the resistor, the signal should be routed with 75
Ω
impedance.
Depending on the layer stack up, 75
Ω
traces cannot be reached due to the width becoming too
small. In this case, lower traces impedance (e.g. 50
Ω)
can be used but the trace length should be
kept short.
All signals on the VGA D-SUB connector need to be ESD protected. TSR diodes can be used. It is
recommended that a PI-filter is added to the analogue RGB signals. The values for the capacitors
and inductors depend on the maximum display resolution required. The PI-filter reduces EMI
problems, but also limits the maximum bandwidth of the VGA signal.
Figure 41: VGA reference schematic
2.9.3
Unused VGA Interface Signal Termination
All unused VGA interface signals can be left unconnected.
2.10 Display Serial Interface (MIPI/DSI)
The MIPI/DSI interface is not a standard interface in the Apalis module family. If a module features
DSI, the according signals are located in the type-specific area of the MXM3 module edge
connector. Toradex tries to keep the position of the signals compatible between the different
modules but as it is not a standard interface it is not guaranteed. For more information to the
interface, please consult the according datasheet of the Apalis module.
VGA1_B_C
VGA1_G_C
VGA1_R_C
GND
SHIELD
1
1
2
3
4
5
6
7
8
9
2
3
4
5
6
7
8
9
HDR15SN-H
10
11
12
13
14
15
10
11
12
13
14
15
X24A
SHIELD
HDR15SN-H
X24B
SHIELD
47pF
50V
C11
GND
500mA
220R@100MHz
L6
SN74LVC1G17DCKR
NC
1
A
2
GND
3
Y
4
VCC
5
IC2
33R
R13
100nF
16V
C12
GND
47pF
50V
C13
GND
500mA
220R@100MHz
L7
SN74LVC1G17DCKR
NC
1
A
2
GND
3
Y
4
VCC
5
IC3
33R
R15
100nF
16V
C14
RCLAMP0504S
D1
10pF
50V
C5
10pF
50V
C6
GND
600mA
40R@100MHz
L3
10pF
50V
C7
10pF
50V
C8
GND
600mA
40R@100MHz
L4
10pF
50V
C9
10pF
50V
C10
GND
600mA
40R@100MHz
L5
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
SHIELD
150R
R10
150R
R11
150R
R12
MM70-314-310B1
VGA1_R
208
Apalis - VGA
23 of 25
VGA1_G
210
VGA1_B
212
VGA1_HSYNC
214
VGA1_VSYNC
216
X1W
VGA1_R
VGA1_G
VGA1_B
VGA1_HSYNC
VGA1_VSYNC
VGA1_HSYNC_C
VGA1_VSYNC_C
5V_SW
5V_SW
PLACE D1, D2 NEAR THE DVI-I CONNECTOR
PCA9306DCTT
GND
1
VREF1
2
SCL1
3
EN
8
SDA1
4
SDA2
5
SCL2
6
VREF2
7
IC1
GND
R1
100K
100nF
16V
C2
GND
R3
1.8K
R2
1.8K
500mA
220R@100MHz
L1
500mA
220R@100MHz
L2
4.7pF
C4
4.7pF
C3
R4
1.8K
R5
1.8K
GND
I2C2_SCL
I2C2_SDA
I2C2_DDC_SDA_C
I2C2_DDC_SCL_C
100nF
16V
C1
I2C2_DDC[0..1]
3.3V_SW
22R
R6
22R
R8
MXM3_205
MXM3_207
MM70-314-310B1
Apalis - Display DDC
25 of 25
I2C2_SDA
205
I2C2_SCL
207
X1Y
I2C2_SDA
I2C2_SCL
22R
R7
22R
R9
5V_SW
V_DISP
RCLAMP0504S
D2
SHIELD
V_DISP
1
2
3
JP1
GND
R14
120R
PIN9
PIN9
I2C2_DDC_SDA_C
I2C2_DDC_SCL_C
I2C2_DDC_C[0..1]
BAT54
D6
V_DISP
5V_SW