L6728A STMicroelectronics, L6728A Datasheet - Page 17

• Manufacturer Part Number: L6728A
• Description: Voltage Mode PWM Controllers Hi-Freq. singl-phase PWM controller w/Po
• Manufacturer: STMicroelectronics

Specifications of L6728A

• Number Of Outputs: Dual Output
• Topology: Buck
• Output Voltage: 0.8 V
• Output Current: 1500 mA
• Switching Frequency: 660 KHz
• Duty Cycle (max): 67 %
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Package / Case: VFDFPN-10 EP
• Synchronous Pin: No
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L6728A
Figure 7.
Gate traces and phase trace must be sized according to the driver RMS current delivered to
the power MOSFET. The device robustness allows managing applications with the power
section far from the controller without losing performances. Anyway, when possible, it is
recommended to minimize the distance between controller and power section.
Small signal components and connections to critical nodes of the application, as well as
bypass capacitors for the device supply, are also important. Locate bypass capacitor (V
and Bootstrap capacitor) and feedback compensation components as close to the device as
practical. For over current programmability, place R
leakage current paths on COMP/OC pin, since the internal current source is only 60 μA.
Systems that do not use Schottky diode in parallel to the Low-Side MOSFET might show big
negative spikes on the phase pin. This spike must be limited within the absolute maximum
ratings (for example, adding a gate resistor in series to HS MOSFET gate), as well as the
positive spike, but has an additional consequence: it causes the bootstrap capacitor to be
over-charged. This extra-charge can cause, in the worst case condition of maximum input
voltage and during particular transients, that boot-to-phase voltage overcomes the absolute
maximum ratings also causing device failures. It is then suggested in this cases to limit this
extra-charge by adding a small resistor in series to the boot capacitor (one resistor in series
to BOOT).
Figure 8.
LS DRIVER
LGATE
GND
VCC
Power connections (heavy lines)
Drivers turn-on and turn-off paths
L6728A
R
UGATE
GATE
PHASE
LGATE
GND
LS MOSFET
R
INT
C
GS
C
GD
C
DS
C
V
IN
IN
L
HS DRIVER
OCSET
C
OUT
close to the device and avoid
PHASE
BOOT
UGATE
LOAD
R
GATE
Application details
HS MOSFET
R
INT
C
GS
C
GD
17/32
CC
C
DS