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Application Note EVB90609L-xx
Mixed mode small gyroscope PCB
Scope
This application note describes the schematic, the layout and the use of the series of small
breakout boards for MLX90609 angular rate sensor. It is fully applicable to EVB90609L-N2,
EVB90609L-E2 and EVB90609L-R2 boards and can be used as reference for populating the
EVB90609L board.
General Description
Figure 1. Top view of EVB90609L board.
EVB90609L-xx PCB is a small board, which
uses the MLX90609 chip in a typical
configuration. It can be directly connected to
customer’s system to ease the development
process. The EVB90609L-xx boards provide
the possibility to work both in analogue and in
digital mode. Both modes are available on
different connector pins of the board. Next to
the MLX90609 chip the board includes
several passive components which are
recommended according to the typical
schematic. The board communicates with
outside world through edge-type 14 pin
connector. Pin names, numbers and functions
are explained in table 1.
Detailed Description
Variants
There are 4 variants of the EVB90609L-xx board, which differs only in MLX90609 chip type used
(see Table 2).
Table 2. Board variants
Board
Order option “xx”
Chip type
Note
EVB90609L
No
Clear board
EVB90609L
N2
MLX90609N2
75 deg/s full range
EVB90609L
E2
MLX90609E2
150 deg/s full range
EVB90609L
R3
MLX90609R2
300 deg/s full range
For more information about the MLX90609 chip and its operation, check the MLX90609
datasheets at www.melexis.com.
ATTENTION: Breakout boards shipped before 2008 do not have the analog output available at
the edge connector. You are NOT concerned if:
• You intend to only use the digital SPI output.
• The carry boxes do have an additional sticker on the top “For the latest documentation check
out our website www.melexis.com”
• The OUTAR edge connector pin is sensitive to angular rate applied for instance by hand.
In all other cases, contact the Melexis representative, distributor or local sales engineer. A
rework instruction can also be found at the end of this document.
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Application Note EVB90609L-xx
Mixed mode small gyroscope PCB
Pinout
Table 1. Pin out of the edge connector
Pin Number
Pin Name Pin Function
1
VCC
Power pin +5V
2
VCC
Power pin +5V
3
VREF
Internal reference voltage
4
SCLK
Cock for SPI
5
OUTAR
Angular rate output voltage
6
-SS
Slave select for SPI (negative logic)
7
OUTTMP
Temperature output voltage
8
MISO
Master-input-slave-output signal for SPI
9
SLFT1
Self test selection pin 1
10
MOSI
Master-output-slave-input-signal for SPI
11
SLFT2
Self test selection pin 2
12
ERROR
Gyro internal error signalization
13
GND
Ground pin
14
GND
Ground pin
Dimensions
A top view of EVB90609L-xx boards is represented in Figure 1. The dimensions of the boards
are: 28 mm (length) x 18 mm (height) x 3.5 mm (thickness).
Schematics
Electrical schematic of the EVB90609L-xx board is presented at Figure 2 as it is based on the
typical schematic from MLX90609 datasheet.
The value of the capacitor C3 defines the output bandwidth of gyro. The –3dB bandwidth set by
C3 is:
fOUT =0.16 /(ROUT*C3), with ROUT = 200kΩ (typ.)
For instance, with C3=82nF the bandwidth is 50Hz.
VCC
C1
100n
R1
10k
SLFT1
SLFT2
R2
10k
1
3
5
7
9
11
13
2
4
6
8
10
12
14
SCLK
-SS
MISO
MOSI
ERROR
EDGIDC14
NC5
CASE
SCLK
VDDA
SS
VSSA
MISO
VREF
U1
MOSI
MLX90609BA OUTAR
TEST
FLT
ERROR
OUTTEMP
SELFTEST
HVIN
28
27
26
25
24
23
22
21
NC13
NC14
NC15
NC16
NC17
NC18
NC19
NC20
ERROR
VREF
OUTAR
OUTTMP
SLFT1
SLFT2
C2 100n
VREF
C3
82n
C5 100n
R3
0
OUTAR
OUTTMP
13
14
15
16
17
18
19
20
5
6
7
8
9
10
11
12
VDD
GND
NC2
TOPCAP4
TOPCAP5
NC31
TESTOUT
TESTIN
4
3
2
1
32
31
30
29
VCC
SCLK
-SS
MISO
MOSI
VCC
J1
Figure 2. Electrical schematic of the MLX90609 boards.
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Application Note EVB90609L-xx
Mixed mode small gyroscope PCB
Component placement and PCB Layout
Component placement at the board is presented at Figure 3.
Figure 3. Component placement.
The layouts of the top and bottom side of the board are presented at Figure 4.
Figure 4. Board top (blue) and bottom (red) side layout.
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Application Note EVB90609L-xx
Mixed mode small gyroscope PCB
Rework Instructions
Do you need to rework?
Rework instructions for breakout boards shipped before March 2008, which do not have the
analog output available at the edge connector. You are NOT concerned if:
• You intend to only use the digital SPI output.
• The carry boxes do have a sticker on the top:
• The OUTAR edge connector pin is sensitive to angular rate applied for instance by hand.
In all other cases, contact the Melexis representative, distributor or local sales engineer or follow
the following rework instruction.
How to rework?
An error had been detected on the first boards. The analog output was not routed correctly to
the output pin of the breakout board It is however quite easy to modify those boards. The
necessary modification is shown at Figure 5. The green square indicates and addition of a zero
Ohm resistor (short circuiting, R3 in Figure 2 and 3).
Figure 5. The modification of the PCB
Revision history
Rev.001 from July 2007. Initial release.
Rev.002 from January 2008. Figure 2 was corrected. The output signal “OUTAR” which had
been erroneously connected to pin 23 “FLT” of U1 was reconnected to pin 24 “OUTAR” of U1
trough jumper R3, which replaced capacitor C4. Figure 3 and Figure 4 were corrected too to
reflect changes of the schematic. Text at page 2 was corrected. The paragraph “Rework
Instructions” which contains explanations how customers themselves can modify boards was
added.
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