ADT7350
DETAILED DESCRIPTION
UVLO (Under Voltage Lock Out)
ADT7350 can monitor the battery output voltage. If the battery output voltage is under 3.8V . The
ADT7350 goes to the UVLO status to save the power consumption of applications.
Oscillator
The ADT7350 has a fixed frequency generator (typical 1.4MHz) and also automatically changes the
operating frequency in accordance with feedback voltage (0.81V) for protecting the load. If the feedback
voltage is under 0.4V, the operating frequency changes to one third of fixed operating frequency. (Typical
460KHz)
Error Amplifier
The high gain error amplifier integrate the error signal from which the difference of reference voltage and
feedback voltage. The summed output Error signal compares with PWM Ramp signal. It provides accuracy
of the voltage feedback loop regulation. The feedback voltage of ADT7350 is typical 0.81V.
Current sense Amplifier
The current sense amplifier output is proportional to the current flowing into the inductor. This output goes
to the comparator to make a proper control signal. The ADT7350 has well compensated current slope
which is added into ramp generator circuit.
Compensation Network
The fixed frequency peak current mode control scheme to provide easy compensation for stability and fast
transient response. The cycle-by-cycle basis monitored peak current of inductor is compared with error
amplifier output voltage. The duty cycle is modulated based on the inductor’s peak current. The inductor
can be emulated to current source. So the inductor’s pole frequency goes to high frequency . It seems to be
one-pole system. The ADT7350 has a inner compensation network in error amplifier block.
* This specifications are subject to be changed without notice
Aug 21. 2012 / Rev. 0.2
8/10
http://www.ad-tech.co.kr
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