L6235PD STMicroelectronics, L6235PD Datasheet - Page 9

• Manufacturer Part Number: L6235PD
• Description: IC DRIVER 3PHASE MOTOR 36PWRSOIC
• Manufacturer: STMicroelectronics
• Type: Driverr

Specifications of L6235PD

• Applications: DC Motor Driver, Brushless (BLDC), 3 Phase
• Number Of Outputs: 1
• Current - Output: 5.6A
• Voltage - Supply: 12 V ~ 52 V
• Operating Temperature: -25°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 36-PowerSOIC
• Operating Supply Voltage: 7 V to 52 V
• Supply Current: 0.006 A
• Mounting Style: SMD/SMT
• Operating Current: 10mA
• Operating Temperature Classification: Automotive
• Package Type: PowerSO
• Operating Supply Voltage (min): 12V
• Operating Supply Voltage (typ): 42V
• Operating Supply Voltage (max): 52V
• For Use With: 497-4935 - BOARD MOTOR BRUSHLESS DC L6235
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Load: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-5354-5; L6235PD

PWM CURRENT CONTROL
The L6235 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 Figure 7. As the current in the motor increases the
voltage across the sense resistor increases proportionally. When the voltage drop across the sense resistor be-
comes 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 conduc-
tion in the bridge, delays the turn on of the power MOS, the effective Off Time t
time plus the dead time.
Figure 8 shows the typical operating waveforms of the output current, the voltage drop across the sensing re-
sistor, 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 re-
verse recovery of the freewheeling diodes. The L6235 provides a 1µs Blanking Time t
comparator output so that the current spike cannot prematurely retrigger the monostable.
Figure 7. PWM Current Controller Simplified Schematic
C
OFF
5V
5mA
(0)
RCOFF
R
TO GATE
OFF
(1)
LOGIC
2.5V
Q
+
-
R
S
MONOSTABLE
BLANKING TIME
MONOSTABLE
SET
1 s
COMPARATOR
SENSE
BLANKER
DEAD TIME
DRIVERS
GATE DRIVERS
+
-
FROM THE
LOW-SIDE
+
R SENSE
VREF
VS
B
SENSE B
DEAD TIME
DRIVERS
+
OFF
is the sum of the monostable
SENSE A
DEAD TIME
DRIVERS
BLANK
+
D02IN1380
VS
A
that inhibits the
L6235
VS
OUT 2
OUT 3
OUT 1
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