L5953
2.6
2.6.1
Functional description
PWM step down voltage regulator
The switching regulator (Figure 11.) inside the L5953 is a voltage control mode (also known
as a direct duty cycle) Buck regulator: the error signal coming from the error amplifier is
compared with a sawtooth to set on and off times of the power switch.
The feedforward control is introduced to get a quickly response to input voltage changes: the
sawtooth has a fixed frequency and an amplitude variable with the battery voltage.
Continuous mode operation is recommended in order to reduce the stress of the output
capacitor and of the free-wheeling diode.
Error amplifier and compensation network
The error amplifier (EA) is a voltage amplifier whose non-inverting input is fixed to the
reference voltage (1.275V bandgap voltage) and whose inverting input and output are
externally available for feedback and frequency compensation.
15/31