AS1301
Data Sheet - Detailed Description
8 Detailed Description
Operating Principle
Functional Description
The AS1301 is a high efficiency and low noise switched capacitor DC/DC converter that is capable of boost operation.
It is equipped with two built-in coupled H-bridge type switch configurations. Based on the value of the output voltage
the system automatically initiates mode up-switching to achieve the highest possible efficiency. The regulation of the
output voltage is achieved by a regulation loop, which modulates the on-resistance of the power transistors so that the
amount of charge transferred from the input to the output at each clock cycle is controlled and is equal to the charge
needed by the load.
Regulation Loop
The AS1301 operates at constant frequency at any load. For the regulation loop power transistors, a resistor divider,
and an error amplifier is used to keep the output voltage within the allowed limits. The error amplifier, including loop-
filter and compensation ramp, takes feedback and reference as inputs and generates the error voltage signal. The
error voltage is then used as the gate voltage of the power transistor which modulates the on-resistance of the latter.
The modulated transistor on-resistance controls the charge transferred from the input to the output and therefore the
regulation of the output is realized. Based on adjusting of the amount of charge transferred, this regulation concept
delivers the smallest voltage ripple possible.
Figure 26. Functional Block Diagram
CFLY1
C1-
CFLY2
C2-
C1+
C2+
VOUT
VBATT
CBAT
Double-H Bridge
Topology
+
COUT
POR
Ref
Vctrl
Temp
Soft
Start
State Machine
&
Mode Select
Vmode trig
Control Logic
CLK
EN
On
Off
AS1301
GND
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