WPMDH1100601 / 171010601
MagI3C Power Module
VDRM – Variable Step Down Regulator Module
BLOCK DIAGRAM
Power Module
Linear
Regulator
CVCC
CBST
10µH
VIN
1
7
VOUT
VIN
VOUT
HSS
0.47µF
CIN
RFBT
COUT
CFF
RON
VIN
UVLO
Controller/
Power Control/
LSS
Comparator
2
5
RON
SS
Protection Circuitry
FB
6
VREF
0.8V
RFBB
EN AGND
PGND
EP
CSS
3
4
AGND
AGND
CIRCUIT DESCRIPTION
The MagI³C Power Module 171010601 is based on a synchronous step-down regulator with integrated MOSFETs and a
power inductor. The control scheme uses a Constant On-Time (COT) low ripple hysteretic regulation loop.
The VOUT of the regulator is divided by the feedback resistor network RFBT and RFBB and fed into the FB pin. The internal
comparator compares this signal with the internal 0.8V reference. If the feedback voltage is below the reference, the high
side MOSFET is turned on for a fixed on-time.
To achieve a regulated output voltage the off-time is modulated. At stable VIN to VOUT condition the relation between on-time
and off-time is constant. The on-time is preset by the value of the RON resistor. The switching frequency is directly
proportional to this value. The connection of the RON resistor to VIN results into an additional compensation of VIN variations,
(VIN feed-forward) so the switching frequency will remain almost constant even during VIN transients.
A load current transient (low to high current) allows the off-time to immediately transition to the minimum of 260 ns. This
results in a short term higher switching frequency which ensures an extremely quick regulation response. As soon as the
output capacitor is recharged to the nominal output voltage the switching frequency will return to the original value even
though the load current is higher.
The constant on-time control scheme does not require compensation circuitry which makes the overall design very simple.
Nevertheless, it requires a certain minimum ripple at the feedback pin. The MagI³C Power Module 171010601 generates this
ripple internally and is supported by the CFF capacitor which bypasses AC ripple directly to the feedback pin from the output.
With this architecture very small output ripple values of around 10mV (similar to current or voltage mode devices) are
achieved.
we-online.com
Würth Elektronik eiSos GmbH & Co. KG – Data Sheet Rev. 1.0
© September 2017
16/54
WURTH [ WURTH ELEKTRONIK GMBH & CO. KG, GERMANY. ]
