AS5311-ASST austriamicrosystems, AS5311-ASST Datasheet - Page 12

• Manufacturer Part Number: AS5311-ASST
• Description: IC ENCODER LINEAR 20-TSSOP
• Manufacturer: austriamicrosystems
• Type: Linear, Rotary Encoder - Programmabler

Specifications of AS5311-ASST

• Voltage - Supply: 3 V ~ 3.6 V, 4.5 V ~ 5.5 V
• Current - Supply: 21mA
• Current - Output (max): 4mA
• Output Type: Digital, PWM, 12-Bit Serial
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 20-TSSOP (0.173", 4.40mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sensing Range: -
• Features: -

AS5311
Data Sheet
7.2 Incremental Output Hysteresis
Figure 7. Hysteresis Illustration
To avoid flickering incremental outputs at a stationary magnet position, a hysteresis is introduced.
In case of a movement direction change, the incremental outputs have a hysteresis of 2 LSB. For constant
movement directions, every magnet position change is indicated at the incremental outputs (see Figure 6). If for
example the magnet moves from position „x+3“ to „x+4“, the incremental output would also indicate this position
accordingly.
A change of the magnet’s movement direction back to position „x+3“ means, that the incremental output still
remains unchanged for the duration of 2 LSB, until position „x+2“ is reached. Following this movement, the
incremental outputs will again be updated with every change of the magnet position.
7.3 Synchronous Serial Interface (SSI)
The Serial interface allows data transmission of the 12-bit absolute linear position information (within one pole
pair = 2.0mm). Data bits D11:D0 represent the position information with a resolution of 488nm (2000µm / 4096)
per step.
CLK must be high at the falling edge of CSn.
Figure 8. Synchronous Serial Interface with Absolute Angular Position Data
If CLK is low at the falling edge of CSn, the first 12 bits represent the magnitude information, which is
proportional to the magnetic field strength. This information can be used to detect the presence and proper
distance of the magnetic strip by comparing it to a known good value (depends on the magnet material and
distance).
The automatic gain control (AGC) maintains a constant MAGnitude value of 3F hex (=”green” range). If the MAG
value is <>3F hex, the AGC is out of the regulating range (“yellow” or “red” range). See Table 5 for more details.
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CSn
CLK
DO
t
DO active
t
CLK FE
1
D11
T
t
CLK/2
DO valid
D10
D9
D8
D7
Angular Position Data
D6
Movement left -> right
Movement right -> left
D5
8
D4
2 steps
D3
Revision 1.04
D2
D1
D0
OCF
COF
Status Bits
LIN
Mag
INC
DEC
Mag
18
Even
PAR
t
DO Tristate
t
CSn
t
CLK FE
1
D11
12 - 24