Application Circuit - Two Phase Bipolar Stepper Motor Driver
VSS
VS
C3
0.1mF
C1 100mF
C2
0.1mF
V
IN1
V
VDD
V
REF
DD
A
CC
B
MAA
OUTA
IN0
CS3717A
CS-3717A
MBA
DIRECTION
Pulse
OUTB
Sense
Gnd
Gnd COMP IN
RC
1kW
CC
CT
1W
RSense
IMA
RT
820pF
CT
820pF
CC
56kW
FROM
m PROCESSOR
RT
1W
RSense
820pF
820pF
RC
56kW
IMB
1kW
STEPPER
MOTOR
Pulse
Gnd
Gnd
Comp In
Sense
Out B
DIRECTION
IN1
IN0
CS3717A
OutA
VDD
VDD
VCC
V
REF
B
A
Mounting Instructions
The RQJA of the CS3717A can be reduced by soldering the
Gnd pins to a suitable copper area of the printed circuit
board or to an external heatsink.
(see fig. 1). In addition, it is possible to use an external
heatsink (see fig. 3). During soldering the pins temperature
must not exceed 260ûC and the soldering time must not be
longer than 12 seconds.
The diagram of fig. 2 shows the maximum dissipated
power Ptot and the RQJA as a function of the side Òl Ó of
two equal square copper areas having a thickness of 35µ
The external heatsink or printed circuit copper area must
be connected to electrical ground.
Ptot
(W)
Rq JA
(ûC/W)
COPPER AREA 35m THICKNESS
4
3
2
1
0
80
60
40
20
0
Rq JA
l
Ptot (Tamb = 70ûC)
l
0
10
20
30
40
I(mm)
P.C. BOARD
Ò l Ó
Figure 1 - Example of P.C. Board Copper Area Which is Used as
Heatsink with 16 lead fused package.
Figure 2 - Max. Power Dissipation And Junction To Ambient Thermal
Resistance vs. Size ÒlÓ for 16 lead fused package.
170mm
Ptot
(W)
5
4
3
2
1
0
WITH INFINITE HEA
HEA
T
- SINK WITH R
th
11.9mm
= 25ûC/W
T
- SINK
38.0mm
FREE AIR
50
100
T
amb
(C)
-50
0
Figure 3 - External Heatsink Mounting Example (Rth = 30ûC/W) for 16
lead batwing package.
Figure 4 - Maximum Allowable Power Dissipation vs. Ambient
Temperature for 16 lead batwing package.
7
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
