CS3717A Datasheet, PDF (7/8 Pages) Cherry Semiconductor Corporation – 1A H-Bridge Stepper Motor Driver

Application Circuit - Two Phase Bipolar Stepper Motor Driver
0.1mF C3 ^VSS
V_S
FROM
m PROCESSOR
R_T
56kW
R_T
56kW
C1 100mF
C2
0.1mF
V_{REF VCC}
IN1
VDDB V_DDA
OUTA
MAA
IN0
CCSS3-731771A7A
DIRECTION
Pulse
Gnd Gnd COMP IN
OUTB
Sense
MBA
R_C
1kW
C_T
C_C
1W
I_MA
820pF
820pF
R_Sense
C_T
820pF
C_C
820pF
R_C
1W
R_Sense
Pulse
Gnd
DIRECTION
1kW
Gnd Comp In
Sense
Out B
IN1
CS3717A
IN0
V_REF
V_CC
V_DDB
OutA
V_DDA
I_MB
STEPPER
MOTOR
Mounting Instructions
The R_QJA 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.
The diagram of fig. 2 shows the maximum dissipated
power P_tot and the R_QJA as a function of the side Òl Ó of
two equal square copper areas having a thickness of 35µ
(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 external heatsink or printed circuit copper area must
be connected to electrical ground.
COPPER AREA 35m THICKNESS
P_tot
(W)
4
3
R_{q JA}
R_{q JA}
(ûC/W)
80
60
l
l
P.C. BOARD
Figure 1 - Example of P.C. Board Copper Area Which is Used as
Heatsink with 16 lead fused package.
170mm
11.9mm
38.0mm
2
40
1
P_tot (T_amb = 70ûC)
20
0
0
0
10
20
30
40 I(mm)
ÒlÓ
Figure 2 - Max. Power Dissipation And Junction To Ambient Thermal
Resistance vs. Size ÒlÓ for 16 lead fused package.
P_tot
(W)
5
4
3
2
1
0
-50
HEAT _{- SINK WITH Rth = 25ûC/W}
FREE _AIR
0
50
100
Tamb (C)
Figure 3 - External Heatsink Mounting Example (R_th = 30ûC/W) for 16
lead batwing package.
Figure 4 - Maximum Allowable Power Dissipation vs. Ambient
Temperature for 16 lead batwing package.
7