L6229QTR STMicroelectronics, L6229QTR Datasheet - Page 13

• Manufacturer Part Number: L6229QTR
• Description: IC DRIVER DMOS DC MOTOR 32VFQFPN
• Manufacturer: STMicroelectronics
• Type: 3 Phase Brushless DC Motor Driverr

Specifications of L6229QTR

• Applications: DC Motor Driver, Brushless (BLDC), 3 Phase
• Number Of Outputs: 1
• Current - Output: 2.8A
• Voltage - Supply: 12 V ~ 52 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Load: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-8495-2

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
13/28