MC33033 Motorola, MC33033 Datasheet - Page 11

• Manufacturer Part Number: MC33033
• Description: BRUSHLESS DC MOTOR CONTROLLER
• Manufacturer: Motorola

oscillator ramp–up period. The stator current is converted to
a voltage by inserting a ground–referenced sense resistor R S
(Figure 34) in series with the three bottom switch transistors
(Q 4 , Q 5 , Q 6 ). The voltage developed across the sense
resistor is monitored by the current sense input (Pin 12), and
compared to the internal 100 mV reference. If the current
sense threshold is exceeded, the comparator resets the
lower latch and terminates output switch conduction. The
value for the sense resistor is:
single output conduction pulse occurs during any given
oscillator cycle, whether terminated by the output of the Error
Amplifier or the current limit comparator.
Reference
current for the oscillator timing capacitor, a reference for the
Error Amplifier, and can supply 20 mA of current suitable for
directly powering sensors in low voltage applications. In
higher voltage applications it may become necessary to
transfer the power dissipated by the regulator off the IC. This
is easily accomplished with the addition of an external pass
NOTES: 1. V = Any one of six valid sensor or drive combinations.
MOTOROLA ANALOG IC DEVICE DATA
S A
1
1
1
0
0
0
1
1
1
0
0
0
1
0
V
V
The dual–latch PWM configuration ensures that only one
The on–chip 6.25 V regulator (Pin 7) provides charging
Sensor Electrical Phasing (Note 4)
2. The digital inputs (Pins 3, 4, 5, 6, 18, 19) are all TTL compatible. The current sense input (Pin 12) has a 100 mV threshold with respect to Pin 13. A
3. The top drive outputs are open collector design and active in the low (0) state.
4. With 60 /120 (Pin 18) in the high (1) state, configuration is for 60 sensor electrical phasing inputs. With Pin 18 in the low (0) state, configuration is
5. Valid 60 or 120 sensor combinations for corresponding valid top and bottom drive outputs.
6. Invalid sensor inputs; All top and bottom drives are off.
7. Valid sensor inputs with enable = 0; All top and bottom drives are off.
8. Valid sensor inputs with enable and current sense = 1; All top and bottom drives are off.
60
S B
V
V
0
1
1
1
0
0
0
1
1
1
0
0
0
1
X = Don’t care.
logic 0 for this input is defined as < 85 mV, and a logic 1 is > 115 mV.
for 120 sensor electrical phasing inputs.
S C
0
0
1
1
1
0
0
0
1
1
1
0
1
0
V
V
R
S A
V
V
1
1
0
0
0
1
1
1
0
0
0
1
1
0
S
+
Figure 19. Three Phase, Six Step Commutation Truth Table (Note 1)
120
Inputs (Note 2)
I
S B
stator(max)
V
V
0
1
1
1
0
0
0
1
1
1
0
0
1
0
0.1
S C
V
V
0
0
0
1
1
1
0
0
0
1
1
1
1
0
F/R
1
1
1
1
1
1
0
0
0
0
0
0
X
X
X
X
Enable
X
X
1
1
1
1
1
1
1
1
1
1
1
1
0
1
MC33033
Current
Sense
X
X
X
0
0
0
0
0
0
0
0
0
0
0
0
1
transistor as shown in Figure 21. A 6.25 V reference level
was chosen to allow implementation of the simpler NPN
circuit, where V ref – V BE exceeds the minimum voltage
required by Hall Effect sensors over temperature. With
proper transistor selection, and adequate heatsinking, up to
one amp of load current can be obtained.
Undervoltage Lockout
prevent damage to the IC and the external power switch
transistors. Under low power supply conditions, it guarantees
that the IC and sensors are fully functional, and that there is
sufficient Bottom Drive Output voltage. The positive power
supply to the IC (V CC ) is monitored to a threshold of 8.9 V.
This level ensures sufficient gate drive necessary to attain
low R DS(on) when interfacing with standard power MOSFET
devices. When directly powering the Hall sensors from the
reference, improper sensor operation can result if the
reference output voltage should fall below 4.5 V. If one or
both of the comparators detects an undervoltage condition,
the top drives are turned off and the Bottom Drive Outputs
are held in a low state. Each of the comparators contain
hysteresis to prevent oscillations when crossing their
respective thresholds.
A dual Undervoltage Lockout has been incorporated to
A T
0
1
1
1
1
0
1
1
0
0
1
1
1
1
1
1
Top Drives
B T
1
0
0
1
1
1
1
1
1
1
0
0
1
1
1
1
Outputs (Note 3)
C T
1
1
1
0
0
1
0
0
1
1
1
1
1
1
1
1
A B
0
0
1
1
0
0
1
0
0
0
0
1
0
0
0
0
Bottom Drives
B B
0
0
0
0
1
1
0
1
1
0
0
0
0
0
0
0
C B
1
1
0
0
0
0
0
0
0
1
1
0
0
0
0
0
(Note 5)
(Note 5)
(Note 6)
(Note 7)
(Note 8)
F/R = 1
F/R = 0
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