Datasheet

I
L
t
200mA
(typ.)
ContinuousCurrentOperation DiscontinuousCurrentOperation
200mA
(typ.)
Current
Sensor
Gate
Driver
Device
Control
GND
EN
FB
VOUT
L
VREF
VIN
Device
Control
StartUp
VIN
VOUT
Current
Sensor
Gate
Driver
Device
Control
GND
EN
FB
VOUT
L
VREF
VIN
Device
Control
StartUp
VIN
VOUT
TPS61220, TPS61221, TPS61222
www.ti.com SLVS776A –JANUARY 2009–REVISED APRIL 2014
9 Detailed Description
9.1 Overview
The TPS6122x is a high performance, high efficient family of switching boost converters. To achieve high
efficiency, the power stage is realized as a synchronous-boost topology. For the power switching, two actively-
controlled low-R
DSon
power MOSFETs are implemented.
9.2 Functional Block Diagrams
Functional Block Diagram (Adjustable Version) Functional Block Diagram (Fixed Output Voltage Version)
9.3 Feature Description
9.3.1 Controller Circuit
The device is controlled by a hysteretic current mode controller. This controller regulates the output voltage by
keeping the inductor ripple current constant in the range of 200 mA and adjusting the offset of this inductor
current depending on the output load. If the required average input current is lower than the average inductor
current defined by this constant ripple current, the inductor current becomes discontinuous to keep the efficiency
high under low-load conditions.
Figure 23. Hysteretic Current Operation
The output voltage V
OUT
is monitored via the feedback network which is connected to the voltage error amplifier.
To regulate the output voltage, the voltage error amplifier compares this feedback voltage to the internal voltage
reference and adjusts the required offset of the inductor current accordingly. In fixed output voltage devices, an
internal feedback network is used to program the output voltage. In adjustable versions an external resistor
divider is required.
The self-oscillating hysteretic current mode architecture is inherently stable and allows fast response to load
variations. This architecture also allows using a wide range of inductor and capacitor values.
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Product Folder Links: TPS61220 TPS61221 TPS61222