XRP7714ILB-0X1C-F Exar Corporation, XRP7714ILB-0X1C-F Datasheet - Page 25
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XRP7714ILB-0X1C-F
Manufacturer Part Number
XRP7714ILB-0X1C-F
Description
IC CTRLR PWM/LDO STP-DWN 40TQFN
Manufacturer
Exar Corporation
Series
-r
Datasheet
1.XRP7714ILB-0X10-F.pdf
(29 pages)
Specifications of XRP7714ILB-0X1C-F
Topology
Step-Down (Buck) Synchronous (4), Linear (LDO) (1)
Function
Any Function
Number Of Outputs
5
Frequency - Switching
1.5MHz
Voltage/current - Output 1
Controller
Voltage/current - Output 2
Controller
Voltage/current - Output 3
Controller
W/led Driver
No
W/supervisor
No
W/sequencer
Yes
Voltage - Supply
4.75 V ~ 25 V
Operating Temperature
-40°C ~ 125°C
Mounting Type
*
Package / Case
*
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Other names
1016-1698
E
Select the Inductor for inductance L and saturation current Isat. Select an inductor with Isat higher
than the programmed over current limit. Calculate inductance from:
Where:
Vin is the converter input voltage
Vout is the converter output voltage
fs is the switching frequency
Irip is the inductor peak-to-peak current ripple (nominally set to 30% of Iout)
Keep in mind that a higher Irip results in a smaller inductance value which has the advantages of
smaller size, lower DC equivalent resistance (DCR), and allows the use of a lower output
capacitance to meet a given step load transient. A higher Irip, however, increases the output
voltage ripple, requires higher saturation current limit, and increases critical conduction. Notice
that this critical conduction current is half of Irip.
Select the output capacitor for voltage rating, capacitance and Equivalent Series Resistance (ESR).
Nominally the voltage rating is selected to be at least twice as large as the output voltage. Select
the capacitance to satisfy the specification for output voltage overshoot/undershoot caused by the
current step load. A sudden decrease in the load current forces the energy surplus in the inductor
to be absorbed by Cout. This causes an overshoot in output voltage that is corrected by power
switch reduced duty cycle. Use the following equation to calculate Cout:
Where:
L is the output inductance
I2 is the step load high current
I1 is the step load low current
Vos is output voltage including the overshoot
Vout is the steady state output voltage
Or it can be expressed approximately by
Here,
© 2011 Exar Corporation
Inductor Selection
Capacitor Selection
XTERNAL
•
∆
Output Capacitor Selection
V
=
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V
OMPONENT
os
−
V
out
is the overshoot voltage deviation.
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Rev. 1.1.6
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