WPMDH1302401 Просмотр технического описания (PDF) - Wurth Elektronik GmbH & Co. KG, Germany.
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WPMDH1302401
Wurth Elektronik GmbH & Co. KG, Germany.
WPMDH1302401 Datasheet PDF : 31 Pages
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WPMDH1302401 / 171032401
MagI³C Power Module
VDRM - Variable Step Down Regulator Module
DESIGN FLOW
7 Steps to design the power application
The next 7 simple steps will show how to select the external components to design your power application:
1. Program output voltage
2. Set operating frequency with RON
3. Select input capacitor
4. Select output capacitor
5. Select soft-start capacitor
6. Select feed forward capacitor
7. Optional: Program under voltage lockout divider
VIN
1
VIN
7
VOUT
VOUT
RON 2.
3.
CIN
RENT
7.
RENB
2
RON
3
EN
Module
6
FB
PGND
EP
4
AGND
SS
5
CSS
5.
RFBT
1.
RFBB
CFF
6.
4.
COUT
Step 1. Select Output Voltage (VOUT)
Output voltage is determined by a divider of two resistors connected between VOUT and ground. The midpoint of the
divider is connected to the FB input. The voltage at FB is compared to a 0.8V internal reference. In normal operation
an on-time cycle is initiated when the voltage on the FB pin falls below 0.8V. The high-side MOSFET on-time cycle
causes the output voltage to rise and the voltage at the FB to exceed 0.8V. As long as the voltage at FB is above
0.8V, on time cycles will not occur.
The ratio of the feedback resistors for a desired output voltage is:
RFBT
RFBB
=
(
VOUT
0.8V
)
−
1
(1)
These resistors should be chosen from values in the range of 1kΩ to 50kΩ.
A table of values for RFBT, RFBB, and RON is included in the applications circuit.
Step 2. Select On-Time Resistor (RON)
Many designs will begin with a desired switching frequency in mind. For that purpose the following equation can be
used.
RON
≊
(1.3
∗
V������
10−10 ∗ fSW(CCM))
(2)
The selection of RON and fSW(CCM) must be confined by limitations in the on-time and off-time for the COT control
section. The on-time of the MagI³C power module timer is determined by the resistor RON and the input voltage VIN. It
is calculated as follows:
tON
=
(1.3
∗
10−10
������
∗
RON)
(3)
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Würth Elektronik eiSos GmbH & Co. KG - Data Sheet - REV 1.0
11/31
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