L6728DTR STMicroelectronics, L6728DTR Datasheet - Page 20

• Manufacturer Part Number: L6728DTR
• Description: IC PWM CTLR 1PH POWERGOOD 10DFN
• Manufacturer: STMicroelectronics

Specifications of L6728DTR

• Pwm Type: Voltage Mode
• Number Of Outputs: 1
• Frequency - Max: 330kHz
• Duty Cycle: 80%
• Voltage - Supply: 5 V ~ 12 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 10-DFN
• Frequency-max: 330kHz
• Duty Cycle (max): 80 %
• Mounting Style: SMD/SMT
• Switching Frequency: 300 KHz
• Operating Supply Voltage: 5 V to 12 V
• Supply Current: 6 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-10432-2

Application information
11
11.1
20/33
Application information
Inductor design
The inductance value is defined by a compromise between the dynamic response time, the
efficiency, the cost and the size. The inductor has to be calculated to maintain the ripple
current (ΔI
value can be calculated with the following equation:
Where F
voltage.
inductor, with V
Increasing the value of the inductance reduces the current ripple but, at the same time,
increases the converter response time to a dynamic load change. The response time is the
time required by the inductor to change its current from initial to final value. Until the inductor
has finished its charging time, the output current is supplied by the output capacitors.
Minimizing the response time can minimize the output capacitance required. If the
compensation network is well-designed, during a load variation the device is able to set a
duty cycle value very different (0% or 80%) from a steady-state one. When this condition is
reached, the response time is limited by the time required to change the inductor current.
Figure 9.
L
=
V
----------------------------- -
F
IN
SW
–
Figure 9
SW
V
⋅
L
ΔI
OUT
) between 20% and 30% of the maximum output current (typ). The inductance
is the switching frequency, V
Inductor current ripple vs output voltage
L
⋅
IN
V
--------------
V
shows the ripple current vs. the output voltage for different values of the
OUT
= 5 V and V
IN
IN
Doc ID 16498 Rev 1
= 12 V.
IN
is the input voltage and V
OUT
is the output
L6728D