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Dual Output Voltage Regulator (VREG3V3V2)
MFR4200 Data Sheet, Rev. 0
210
Freescale Semiconductor
4.2.3
V
DD
, V
SS
— Regulator Output1 (Core Logic)
Signals V
DD
/V
SS
are the primary outputs of VREG3V3V2 that provide the power supply for the core
logic. These signals are connected to device pins to allow external decoupling capacitors (100 nF...220 nF,
X7R ceramic).
In shutdown mode an external supply at V
DD
/V
SS
can replace the voltage regulator.
4.2.4
V
DDOSC
, V
SSOSC
— Regulator Output2 (OSC)
Signals V
DDOSC
/V
SSOSC
are the secondary outputs of VREG3V3V2 that provide the power supply for the
oscillator. These signals are connected to device pins to allow external decoupling capacitors (100 nF...220
nF, X7R ceramic).
In shutdown mode an external supply at V
DDOSC
/V
SSOSC
can replace the voltage regulator.
4.2.5
V
REGEN
— Optional Regulator Enable
This optional signal is used to shutdown VREG3V3V2. In that case V
DD
/V
SS
and V
DDOSC
/V
SSOSC
must
be provided externally. shutdown mode is entered with V
REGEN
being low. If V
REGEN
is high, the
VREG3V3V2 is in reduced-power mode.
For the connectivity of V
REGEN
see device overview chapter.
NOTE
Switching from FPM or RPM to shutdown of VREG3V3V2 and vice versa
is not supported while the CC is powered.
4.3
Functional Description
Block VREG3V3V2 is a voltage regulator as depicted in
Figure 4-1
. The regulator functional elements are
the regulator core (REG), a power-on reset module (POR) and a low-voltage reset module (LVR). There
is also the regulator control block (CTRL) which manages the operating modes of VREG3V3V2.
4.3.1
REG — Regulator Core
VREG3V3V2, respectively its regulator core has two parallel, independent regulation loops (REG1 and
REG2) that differ only in the amount of current that can be sourced to the connected loads. Therefore, only
REG1 providing the supply at V
DD
/V
SS
is explained. The principle is also valid for REG2.
The regulator is a linear series regulator with a bandgap reference in its full-performance mode and a
voltage clamp in reduced-power mode. All load currents flow from input V
DDR
to V
SS
or V
SSOSC
, the
reference circuits are connected to V
DDA
and V
SSA
.
4.3.2
Full-performance Mode
In full-performance mode, a fraction of the output voltage (V
DD
) and the bandgap reference voltage are
fed to an operational amplifier. The amplified input voltage difference controls the gate of an output driver.