AN2808 Datasheet, PDF (36/40 Pages) STMicroelectronics – The PM6670S device is a complete

PM6670S evaluation tests
AN2808
Figure 44. Efficiency vs load – VDDQ = 2.5 V, Vin = 12 V
100
90
80
70
60
50
40
30
20
10
0
0.001
0.010
0.100
Current [A]
Forced PWM
Pulse Skip
NO AUD. PS
1.000
10.000
AM00666v1
Figure 45. Efficiency vs load – VDDQ = 2.5 V, Vin = 5 V
100
90
80
70
60
50
Forced PWM
40
Pulse Skip
30
NO AUD. PS
20
10
0
0.001
0.010
0.100
1.000
10.000
Current [A]
AM00667v1
When the input voltage is equal to 5 V the VDDQ rail efficiency is higher than 90%, with a
load greater than 4 mA. This can also be achieved with a very low load when the pulse skip
or non-audible pulse skip working mode is selected. The following two graphs show how the
switching frequency can change with the load: by decreasing the switching frequency the
regulator can greatly increase the efficiency.
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