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RC5011
PRODUCT SPECIFICATION
6
A
Notebook Power Supply Application
RC5011/RC5023 System
The RC5011/RC5023 Portable Power Supply System is
designed to cost-effectively address the notebook computer
power supply requirements. The RC5011 generates the
+12V power supply while also providing the startup 5V
supply current for the RC5023. The RC5011 is designed on a
high voltage technology which can support battery voltages
as high as 32V. The 5V linear regulator from the RC5011
rejects the large potential battery voltage changes and pro-
vides a well-regulated +5V to power the RC5023. To opti-
mize efficiency, the RC5023 utilizes an internal 5V switch to
remove the +5V supply coming from the RC5011 and to
then utilize the efficient +5V switcher output to supply the
power for the digital logic, analog control circuitry, and out-
put drivers of the RC5023.
The RC5023 has an internal comparator which senses the
difference between the regulator 5V from the RC5011 and
the output of the 5V switch-mode regulator. When the
switch-mode regulator output exceeds 4.5V, the comparator
commands the analog switch within the RC5023 to convert
the +5V supply source from the RC5011 to the +5V switch-
mode output. Thus, power is now drawn from the 88% effi-
cient switch-mode regulator rather than the less efficient 5V
linear regulator in the RC5011. The 5V linear regulator in
the RC5011 remains connected to the RC5023 and continues
to power both the bandgap reference as well as the 5Vswitch
comparator; however the current consumption of these
blocks is small and will not have a significant effect on the
overall efficiency of the power supply system.
Figure 3. Notebook Computer Power Supply System using the RC5011 and RC5023
RC5011
RC5023
OSC
OSC
+2.9V
AC
DET
AC ON
System
Battery
6-22V
Power
Management
Unit
AC
EN12V
EN5V
EN5
EN3.3
EN2.9
AC
Docking
Adaptor
Low Bat
Bat
+12V
+12V (PCMCIA)
+5V (Disk)
+3.3V (Logic)
+2.9V (CPU)
+5V
+3.3V
5V
Switch
5V
LIN
V
REF
V
REF
V
BAT