as5134 austriamicrosystems, as5134 Datasheet - Page 21

• Manufacturer Part Number: as5134
• Description: 360?programmable High Speed Bldc Magnetic Rotary Encoder
• Manufacturer: austriamicrosystems

AS5134
Data Sheet - D e t a i l e d D e s c r i p t i o n
Figure 15. Low/Mid Power Mode Connection
In Low/Mid Power Mode, the AS5134 is inactive. The last state, e.g. the angle, AGC value, etc. is frozen and the chip
starts from this frozen state when it resumes active operation. This method provides much faster start-up than a “cold
start” from zero. If the AS5134 is cycled between active and reduced current mode, a substantial reduction of the
average supply current can be achieved. The minimum dwelling time is <0.5 ms. The actual active time depends on
how much the magnet has moved while the AS5134 was in reduced power mode. The angle data is valid, when the
status bit LOCK has been set. Once a valid angle has been measured, the AS5134 can be put back to reduced power
mode. The average power consumption can be calculated as:
Where:
I
I
I
t
t
Reducing Power Supply Peak Currents
An optional RC-filter (R1/C1) may be added to avoid peak currents in the power supply line when the AS5134 is
toggled between active and reduced power mode. R1 must be chosen such that it can maintain a VDD voltage of 4.5 –
5.5V under all conditions, especially during long active periods when the charge on C1 has expired. C1 should be
chosen such that it can support peak currents during the active operation period. For long active periods, C1 should be
large and R1 should be small.
Power Cycling Mode
The power cycling method shown in
transistor high side switch. This mode provides the least power consumption of all three modes; when the sampling
interval is more than 400ms, as the current consumption in off-mode is zero. It also has the longest start-up time of all
modes, as the chip must always perform a “cold start“ from zero, which takes about 1.3 ms. The optional filter R1/C1
may again be added to reduce peak currents in the 5V power supply line.
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avg
active
power_down
on
off
= Time period during which the chip is operated in active mode
= Time period during which the chip is in reduced power mode
= Average current consumption
= Current consumption in active mode
= Current consumption in reduced power mode
I
avg
C1
=
I
-------------------------------------------------------------------- -
active
100n
∗ t
on
Figure 16
t
on
+
AS5134
I
+
powerdown
t
off
S
VDD
VSS
cycles the AS5134 by switching it on and off, using an external PNP
N
∗ t
off
C2
Revision 1.6
I
I
on
off
CS
DCLK
DIO
R1
sampling interval = t
t
on
t
off
on/off
Controller
VDD
VSS
Micro
on
+ t
off
VDD
+5V
VSS
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(EQ 5)