L6743D STMicroelectronics, L6743D Datasheet - Page 10

• Manufacturer Part Number: L6743D
• Description: IC MOSFET DRIVER DUAL 8SOIC
• Manufacturer: STMicroelectronics
• Type: High Current Mosfet Driverr

Specifications of L6743D

• Configuration: High and Low Side, Synchronous
• Input Type: PWM
• Delay Time: 30ns
• Current - Peak: 2A
• Number Of Configurations: 1
• Number Of Outputs: 2
• High Side Voltage - Max (bootstrap): 41V
• Voltage - Supply: 5 V ~ 12 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Product: Driver ICs - Various
• Propagation Delay Time: 75 ns
• Supply Voltage (max): 12 V
• Supply Voltage (min): 5 V
• Supply Current: 5 mA
• Maximum Power Dissipation: 1.15 W
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: 0 C
• Number Of Drivers: 2
• Output Voltage: 10 V
• Flexible Gate-drive: 5 V to 12 V compatible
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Device description and operation
4.4
10/16
To prevent bootstrap capacitor to extra-charge as a consequence of large negative spikes,
an external series resistance R
BOOT pin.
Bootstrap capacitor needs to be designed in order to show a negligible discharge due to the
high-side MOSFET turn-on. In fact it must give a stable voltage supply to the high-side driver
during the MOSFET turn-on also minimizing the power dissipated by the embedded Boot
Diode.
bootstrap according to the desired discharge and depending on the selected MOSFET.
Figure 5.
Power dissipation
L6743D embeds high current drivers for both high-side and low-side MOSFETs: it is then
important to consider the power that the device is going to dissipate in driving them in order
to avoid overcoming the maximum junction operative temperature.
Two main terms contribute in the device power dissipation: bias power and drivers' power.
●
●
When designing an application based on L6743D it is recommended to take into
consideration the effect of external gate resistors on the power dissipated by the driver.
External gate resistors helps the device to dissipate the switching power since the same
power P
resulting in a general cooling of the device.
2.5
2.0
1.5
1.0
0.5
0.0
0
Device power (P
supply pins and it is simply quantifiable as follow:
Drivers' power is the power needed by the driver to continuously switch ON and OFF
the external MOSFETs; it is a function of the switching frequency and total gate charge
of the selected MOSFETs. It can be quantified considering that the total power P
dissipated to switch the MOSFETs dissipated by three main factors: external gate
resistance (when present), intrinsic MOSFET resistance and intrinsic driver resistance.
This last term is the important one to be determined to calculate the device power
dissipation.
The total power dissipated to switch the MOSFETs results:
P
P
DC
SW
Figure 5
10
Cboot = 47nF
Cboot = 100nF
Cboot = 220nF
Cboot = 330nF
Cboot = 470nF
SW
=
=
20
will be shared between the internal driver impedance and the external resistor
V
F
Bootstrap capacitance design
CC
SW
High-Side MOSFET Gate Charge [nC]
30
gives some guidelines on how to select the capacitance value for the
⋅
⋅
I
(
CC
40
Q
GHS
+
DC
50
V
) depends on the static consumption of the device through the
PVCC
⋅
PVCC
60
⋅
70
I
BOOT
PVCC
+
80
Q
GLS
(in the range of few ohms) may be required in series to
90
⋅
VCC
100
)
2500
2000
1500
1000
500
0
0.0
0.2
Boot Cap Delta Voltage [V]
0.4
0.6
Qg = 10nC
Qg = 25nC
Qg = 50nC
Qg = 100nC
0.8
L6743D
SW
1.0