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| E-L5973AD Datasheet, PDF (10/22 Pages) STMicroelectronics – 2 A switch step down switching regulator | |||
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Functional description
Figure 6. Current limitation circuitry
VCC
IOFF
DRIVER
RSENSE
A1
A2
OUT
A1/A2=95
I
PWM
L5973AD
RTH
IL
I NOT
D00IN1134
4.5
Error amplifier
The voltage error amplifier is the core of the loop regulation. It is a transconductance
operational amplifier whose non inverting input is connected to the internal voltage
reference (1.235 V), while the inverting input (FB) is connected to the external divider or
directly to the output voltage. The output (COMP) is connected to the external compensation
network.
The uncompensated error amplifier has the following characteristics:
Table 5. Uncompensated error amplifier
Transconductance
Low frequency gain
Minimum sink/source voltage
Output voltage swing
Input bias current
2300 μS
65 dB
1500 μA/300 μA
0.4 V/3.65 V
2.5 μA
The error amplifier output is compared with the oscillator sawtooth to perform PWM control.
10/22
Doc ID 9552 Rev 9
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