PBD3517-1 Datasheet, PDF (4/10 Pages) Ericsson – Stepper Motor Drive Circuit

PBD 3517/1
Output Current [A]
10
T_A= +25° C
8
6
4
2
0
0
0.2
0.4
0.6
0.8 1.0
Output Voltage [V]
Figure 7. Typical I_Ø vs. V_{ØCE Sat}. “Zero
output” saturation.
Output Pulse Width [s]
1
T_A= +25° C
10 ^-1
10 ^-2
10 ^-3
Rt ^{= 10M}
Rt ^{= 100k}
Rt ^{= 10k}
10 ^-4
Rt ^{= 1k}
10 ^-5
10 ^-6
0.01
0.1
1
10
100
Ct Capacitance [nF]
1000
Figure 8. Typical t_On vs. C_T/R_T. Output
pulse width vs. capacitance/resistance.
Output Pulse Width [s]
1
10 ^-1
100%
T_A= +25° C
10 ^-2
10 ^-3
10 ^-4
10%
50% ^Dutycykle
1%
25%
10 ^-5
0.1%
10 ^-6
0.001 0.01
0.1
1
10 100
fs Step frequency [kHz]
Output Current [A]
0.5
T_A= +25° C
0.4
(II = 0)
0.3
0.2
0.1
0
0
0.2
0.4
0.6
0.8 1.0
Power Dissipation [W]
Figure 9. Typical t vs. f /dc. Output pulse Figure 10. Typical P vs. I . Power
On
s
DP
P
width vs. step frequency/duty cycle.
dissipation without second-level supply
(includes 2 active outputs = FULL STEP).
Output Current [A]
-0.5
T_A= +25° C
-0.4
10%
-0.3
50%
-0.2
-0.1
(Ip = 0)
100%
Motor Current [mA]
350
Normal
Bilevel
Bilevel without
time limit
Diagrams
How to use the diagrams:
1. What is the maximum motor current
in the application?
• The ambient temperature sets the
maximum allowable power
dissipation in the IC, which
relates to the motor currents and
the duty cycle of the bilevel
function. For PBD 3517/1, without
any measures taken to reduce
the chip temperature via
heatsinks, the power dissipation
vs. temperature follows the curve
in figure 4.
• Figures 9 and 10 give the
relationship between motor
currents and their dissipations.
The sum of these power dissipa-
tions must never exceed the
previously-established value, or
life expectancy will be drastically
shortened.
• When no bilevel or voltage
doubling is utilized, the maximum
motor current can be found
directly in figure 9.
2. How to choose timing components.
• Figure 7 shows the relationship
between C_T, R_T, and t_On. Care
must be taken to keep the t_On time
short, otherwise the current in the
winding will rise to a value many
times the rated current, causing
an overheated IC or motor.
3. What is the maximum t_On pulse-width
at a given frequency?
• Figure 8 shows the relationship
between duty cycle, pulse width,
and step frequency. Check
specifications for the valid
operating area.
4. Figures 4, 5 and 6 show typical
saturation voltages vs. output current
levels for different output transistors.
5. Shaded areas represent operating
conditions outside the safe operating
area.
0
0
0.2
0.4
0.6
0.8 1.0
Power Dissipation [W]
Figure 11. Typical P_DI vs. I_I. Power
dissipation in the bilevel pulse when
raising to the I_I value. One active output.
4
t_ON
Time
Figure 12 . Motor Current 1_p.