ML4411CS View Datasheet(PDF) - Micro Linear Corporation
Part Name
Description
MFG CO.
'ML4411CS' PDF : 14 Pages View PDF
ML4411/ML4411A
10K
10K
10K
+V
+V
0.5Ω
1.2K 0.01
1
2
3
+12
4
5
6
7
+5
8
9
10
11
0.02
12
13
+12
14
0.01
GND
ICMD 28
P1
ILIMIT 27
P2
BRAKE 26
VCC2
VCC 25
P3
PH3 24
COTA
PH2 23
CBRK
PH1 22
DIS PWR
IRAMP 21
N1
RC 20
N2
+5V 19
N3
ENABLE E/A 18
ISENSE
PWR FAIL 17
COS
RESET 16
CVCO VCO/TACH OUT 15
3.3K
+12
+5
+
10K
–
+5
+12
1M
+5
+5
1M
2.2
CDLY
Figure 15. ML4411 Unipolar Drive Application
In unipolar operation, the motor‘s windings must be
allowed to drive freely to:
VF(MAX) = VSUPPLY (MAX) + VEMF (MAX)
Therefore, there can be no diodes to clamp the inductive
energy to VSUPPLY. This energy must be clamped,
however, to avoid an over-voltage condition on the
MOSFETs and other components. Typically, a VCLAMP
voltage is created to provide the clamping voltage. The
inductive energy may either be dissipated (Figure 16) or
alternately efficiently regenerated back to the system
supply (Figure 17).
The circuit in Figure 15 is designed to minimize the
external components necessary, at some compromise to
performance. The 3 resistors from the motor phase
windings to the PH inputs work with the ML4411‘s 8Ký
internal resistance to ground to divide the motor‘s
phase voltage down, providing input signals that do not
exceed 12V.
VCLAMP = +24V
12V
BATTERY
+12V
C1
0.1
5V
REG
12V
LDO
+5V
10
0.1
+12V TO
VCC AND VCC2
1000
0.1
This circuit uses analog speed regulation. The 1Mý
resistor from Pin 20 to the speed regulation op amp
provides the function of injecting current into the VCO
loop filter for the open loop stepping phase of start-up
operation. The “one shot” circuitry to time the reset is
replaced by a diode and RC delay from the rising edge or
the POWERFAIL signal. The error amplifier is left enabled
continuously since at low speeds its current contribution
is negligible. The current injected into the loop filter must
be greater than the leakage current from the phase
detector amplifier for the motor to start reliably.
VCLAMP = +24V
50% DUTY
CYCLE
12V
BATTERY
L1
D1
0.1
5V
REG
12V
LDO
Figure 17. Non-Dissipative Clamping Technique
Figure 16. Dissipative Clamping Technique
12
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