GSD200 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
GSD200 Datasheet PDF : 17 Pages
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GS-D200/GS-D200S
Figure 19: Multimotor Synchronization. Large and Small Motor. Slow Current Decay
THERMAL OPERATING CONDITIONS
In many cases the modules do not require any
additional cooling because the dimensions and the
shape of the metal box are studied to offer the
minimum possible thermal resistance case-to-am-
bient for a given volume.
It should be remembered that these modules are a
power device and, depending on ambient tempera-
ture, an additional heath-sink or forced ventilation
or both may be required to keep the unit within safe
temperature range. (Tcasemax < 85 °C during op-
eration).
The concept of maximum operating ambient tem-
perature is totally meaningless when dealing with
power components because the maximum operat-
ing ambient temperature depends on how a power
device is used.
What can be unambiguously defined is the case
temperature of the module.
To calculate the maximum case temperature of the
module in a particular applicative environment the
designer must know the following data:
– Input voltage
– Motor phase current
– Motor phase resistance
– Maximum ambient temperature
From these data it is easy to determine whether an
additional heath-sink is required or not, and the
relevant size i.e. the thermal resistance.
The step by step calculation is shown for the follow-
ing example (GS-D200).
Vin = 40 V, Iphase = 1 A, Rph Phase resistance =
=10Ω, max. TA = 50 °C
q Calculate the power dissipated from the indexer
logic and the level shifter (see electrical charac-
teristics):
Plogic = (5 V • 60 mA) + (40 V • 20 mA) = 1.1 W
q Calculate the average voltage across the winding
resistance:
Vout = (Rph • Iout) = 10Ω ζ 1 A = 10 V
qCalculate the required ON duty cycle (D.C.) of the
output stage to obtain the average voltage (this
D.C. is automatically adjusted by the GS-D200):
D.C.
=
Vout
Vin
=
10
40
=
0.25
q Calculate the power dissipation of the GS-D200
output power stage. The power dissipation de-
pends on two main factors:
– the selected operating mode (FAST or SLOW
DECAY)
– the selected drive sequence (WAVE, NORMAL,
HALF STEP)
FAST DECAY. For this mode of operation, the
internal voltage drop is Vsatsource + Vsatsink during
the ON period i.e. for 25 % of the time.
During the recirculation period (75 % of the time),
the current recirculates on two internal diodes that
have a voltage drop Vd = 1 V, and the internal sense
resistor (0.5 Ω). For this example, by assuming
maximum values for conservative calculations, the
power dissipation during one cycle is:
Ppw = 1.1 • [2 Vsat • Iph • D.C. + 2 Vd • Iph •
(1 - D.C.) + 0.5 • Iph]
14/17
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