PM6681A STMicroelectronics, PM6681A Datasheet - Page 27

• Manufacturer Part Number: PM6681A
• Description: Dual synchronous step down controller with adjustable LDO
• Manufacturer: STMicroelectronics

PM6681A
Table 8.
The adjustable linear regulator is supplied by LDO5 output. It turns on after LDO5 power up
sequence.
It can provide up to 100 mA peak current. Set up the feedback resistor divider according to
the following formula, to regulate a voltage from 0.9 V to 3.3 V.
Equation 12
where LDO is the desired output voltage, Vr = 0.9 V is the internal reference voltage and R
and R
Figure 38. LDO linear regulator
Bypass LDO5 and LDO output with 1-10 µ F ceramic capacitor and a 4,7 µ F tantalum
capacitor (ESR ≥ 2 Ω ).
Switching 5 V
External 5 V
supply
V5SW
output
GND
down
are the resistors of the feedback divider, as shown in
V5SW multifunction pin
The 5 V linear regulator is always turned on and supplies LDO5 output.
The 5 V linear regulator is turned off when the voltage on V5SW is above 4.8 V and
LDO5 output is supplied by the switching 5 V output.
The 5 V linear regulator is turned off when the voltage on V5SW is above 4.8 V and
LDO5 output is supplied by the external 5 V.
LDO
=
V
r
×
⎛
⎜
⎜
⎝
1
Description
+
R
R
down
up
⎞
⎟
⎟
⎠
Figure 38
Device description
:
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