EVAL6229QR STMicroelectronics, EVAL6229QR Datasheet - Page 13

• Manufacturer Part Number: EVAL6229QR
• Description: BOARD DEMO L6229Q BLDC MOT CTRL
• Manufacturer: STMicroelectronics
• Type: Motor / Motion Controllers & Driversr

Specifications of EVAL6229QR

• Main Purpose: Power Management, Motor Control
• Embedded: No
• Utilized Ic / Part: L6229Q
• Primary Attributes: 3-Ph BLDC, 8 ~ 52V Output, PWM Current Control, Brake Function
• Secondary Attributes: Over Current, Cross Conduction & Temperature Protection
• Maximum Operating Temperature: + 125 C
• Operating Supply Voltage: 8 V to 52 V
• Product: Power Management Development Tools
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: L6229Q
• Other names: 497-10748

L6229Q
5.3
PWM current control
The L6229Q includes a constant off time PWM current controller. The current control circuit
senses the bridge current by sensing the voltage drop across an external sense resistor
connected between the source of the three lower power MOS transistors and ground, as
shown in
resistor increases proportionally. When the voltage drop across the sense resistor becomes
greater than the voltage at the reference input pin VREF the sense comparator triggers the
monostable switching the bridge off. The power MOS remain off for the time set by the
monostable and the motor current recirculates around the upper half of the bridge in slow
decay mode as described in the next section. When the monostable times out, the bridge
will again turn on. Since the internal dead time, used to prevent cross conduction in the
bridge, delays the turn on of the power MOS, the effective off time t
monostable time plus the dead time.
Figure 10
across the sensing resistor, the pin RC voltage and the status of the bridge. More details
regarding the synchronous rectification and the output stage configuration are included in
the next section.
Immediately after the power MOS turn on, a high peak current flows through the sense
resistor due to the reverse recovery of the freewheeling diodes. The L6229Q provides a 1 µs
blanking time t
prematurely re trigger the monostable.
Figure 9.
C
OFF
5V
5mA
Figure
(0)
shows the typical operating waveforms of the output current, the voltage drop
PWM current controller simplified schematic
RCOFF
R
TO GATE
OFF
BLANK
(1)
LOGIC
9. As the current in the motor increases the voltage across the sense
2.5V
Q
that inhibits the comparator output so that the current spike cannot
+
-
S
R
MONOSTABLE
BLANKING TIME
MONOSTABLE
Doc ID 15209 Rev 3
SET
1μs
COMPARATOR
SENSE
BLANKER
DEAD TIME
DRIVERS
GATE DRIVERS
+
-
FROM THE
LOW-SIDE
+
R SENSE
VREF
VS
B
SENSE B
DEAD TIME
DRIVERS
+
SENSE A
OFF
DEAD TIME
DRIVERS
is the sum of the
Circuit description
+
D02IN1380
VS
A
VS
OUT 2
OUT 3
OUT 1
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