NSD-2101_07 Datasheet, PDF (9/23 Pages) ams AG – Piezo Motor Driver ASIC for SQL-RV Series Reduced Voltage SQUIGGLE RV and UTAF Motors

NSD-2101
Datasheet - Detailed Description
The rise and fall time definition is shown in Figure 5. Time between crossing 10% and 90% threshold of minimum VDD is measured, 10% to 90%
for rise time and 90% to 10% for fall time. A full bridge switching cycle will take longer.
Figure 5. Rise / Fall Time Definition
V(half-bridge)
VDD = 2.3V
90%
10%
0V
tr
t
tf
In Figure 6, the effect of current limit in the output drivers is shown. Each half-bridge output can deliver 1000mA.
Figure 6. Output Driver Current Limit
ill ^{I(half-bridge)}
t _{Ilim = 1600mA}
G _{s Ilim = 1000mA}
A ^t _0mA
typ 1300mA
t
ms ^{ten 7.2 Power Dissipation Control}
Following techniques are implemented to keep the system and on-chip power dissipation low.
a ^{n Selectable half bridge mode depending on input supply voltage}
Selective charge control for full bridge mode
o _{Hybrid Control for full bridge mode}
c _{Table 7. Power Dissipation Control}
l ^Symbol
Parameter
Conditions
Min Typ Max
Selectable half-bridge
a _HBthr
Rising Threshold
When half-bridge mode is enabled then the output driver 4.3 4.5
4.7
will switch to half-bridge drive depending on input supply
ic^{voltage. Typical system power dissipation can be reduced}
down to 25% of standard full-bridge drive. When VDD is
n ^HBthf
Falling Threshold
higher than 5.0V only half bridge mode should be used to
avoid exceeding max total power dissipation of 1W. A
4.2
4.4
4.6
typical hysteresis of 100mV is implemented to increase
immunity against supply disturbances.
h _{Selective charge control for full-bridge}
c By adding an additional state in the full bridge switching
SCC_PDS Power dissipation saving scheme the power dissipation can be reduced due to the 30
50
e ^{fact that the effective voltage on the capacitor is reduced.}
T^{Hybrid Control for full-bridge}
With this technique the power dissipation can be reduced
by switching periodically from full-bridge to half-bridge
PS_PDS
Power dissipation saving
mode. Power saving in comparison to standard full-bridge
drive is mainly depending on duty cycle between half-
75
bridge and full-bridge. Hybrid Control is also used for
speed control.
valid
Units
V
V
%
%
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