L6223 STMicroelectronics, L6223 Datasheet - Page 20

• Manufacturer Part Number: L6223
• Description: DMOS PROGRAMMABLE HIGH SPEED UNIPOLAR STEPPER MOTOR DRIVER
• Manufacturer: STMicroelectronics

L6223
R
R
R
R
V
V
DC = 15.6%
T
T
PdL = 1.1W
PdH = 0.4W
Pdch = 0.20W
Pdo = 0.24W
At last:
P
The needed thermal resistance between junction
and ambient must be equal to:
Figure 24: Motor current Ip during t
Figure 25: Slow decay of the motor current I
20/33
p
1
ON
OFF
tot
DSON
DSON
S
tot
= 8 msec
= 250 s
= 0.36
= 12.5
= 1.94W
= 26.24V
= 9.7
L =
H =
1.2 = 2
0.7 = 1.15
(During the chopping)
(During the chopping)
(During the phase change)
ON
(phase MA; Q5 and R
p
/2 during t
R
The worst case here considered requires an
heatsink of 25 C/W. The calculation of the power
dissipation by considering the current imbalance
and by simulating a typical motion needed to
carry the head of a printer for example, becomes
full of difficulties. The use of the Personal Com-
puter is helpful in such a case: few examples are
shown from Fig. 28ab until Fig. 31 ab.
Each figure shows the Application Datas and one
diagram where the Total Dissipated Power versus
the peak of the motor current is plotted.
A max Ambient temperature of 70 C and a max
junction temperature of 150 C have been consid-
ered for a few applications using one single de-
vice and a dual device configuration to drive one
off
thj amb
(phase MA).
S
sre common whit the phase MB).
T
jmasc
P
T
tot
ambmasc
39 C/W