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

Application Circuit - Two Phase Bipolar Stepper Motor Driver
FROM
µ PROCESSOR
0.1µF C3 ^VSS
V_S
R_T
56kΩ
R_T
56kΩ
C1 100µF
C2
0.1µF
V_{REF VCC}
IN1
VDDB V_DDA
OUTA
MAA
IN0
CCSS3-731771A7A
DIRECTION
Pulse
Gnd Gnd COMP IN
OUTB
Sense
MBA
R_C
1kΩ
C_T
C_C
1Ω
I_MA
820pF
820pF
R_Sense
C_T
820pF
C_C
820pF
R_C
1Ω
R_Sense
Pulse
Gnd
DIRECTION
1kΩ
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_ΘJA 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_ΘJA as a function of the side “l ” 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 tempera-
ture must not exceed 260°C 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 35µ THICKNESS
P_tot
(W)
4
3
R_{θ JA}
R_{θ JA}
(˚C/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 = 70˚C)
20
0
0
0
10
20
30
40 I(mm)
“l”
Figure 2 - Max. Power Dissipation And Junction To Ambient Thermal
Resistance vs. Size “l” for 16 lead fused package.
P_tot
(W)
5
4
3
2
1
0
-50
HEAT _{- SINK WITH Rth = 25˚C/W}
FREE _AIR
0
50
100
Tamb (C)
Figure 3 - External Heatsink Mounting Example (R_th = 30°C/W) for 16
lead batwing package.
Figure 4 - Maximum Allowable Power Dissipation vs. Ambient
Temperature for 16 lead batwing package.
7