W83301DR Winbond Electronics Corp America, W83301DR Datasheet - Page 9

• Manufacturer Part Number: W83301DR
• Description: Description = Acpi-str Controller With DDR Bus Termination Regulator ;; Package = Tssop 24
• Manufacturer: Winbond Electronics Corp America

7.3 Charge Pump
the W83301DR-O integrates with a switched-capacitor voltage doublers charge pump to
provide a higher driving voltage (Up to 10 volt) and can drive single N-channel MOSFETs in
each output.
7.4 Power OK
normally. When the system jump from the state S3 to the state S0, the W83301DR-O will
monitor the input signal from PWOK pin to ensure that external system power is OK and
then will switches each outputs into the S0 state; In the other hand, the W83301DR-O will
pulls down the Power OK signal to inform the system a over current and induce under-
voltage occurred.
7.5 Soft-Start
5Vdual/3Vdual and STR voltages need to ramp up from 0V to the setting values
respectively. The charging current flowing to output capacitors must be limited to avoid
supply drop-off.
(Css) to generate a linear ramp-up voltage on SS pin (Vss). The Vss slews from 0V to about
9V during the above-mentioned state transitions, and the Vss slew rate is used to clamp the
ramp-up rate of 5Vdual and STR output voltages. This output clamping allows power-ups
free of supply drop-off events.
charge any output capacitor can be calculated with the following formula:
current: the bus-terminator is input clamped, and its output voltage slew-rate, so as its
charging current, will be limited to half of that of STR1.
mentioned above will be prolonged to much. Before Vss ramps up to its upper limit (about
9V), the state transition will not be completed and will not go into next state.
In order to simply the design circuit and provide a cost-effective solution for customer,
The W83301DR-O use a bi-direction Power OK signal to ensure the system can work
During the ‘S5off’ to the ‘S5on’ and the ‘S5on’ to the ‘S0’ state transitions, the
In W83301DR-O, an internal 18 uA current source (Iss) charges an external capacitor
Since the outputs are ramped up in a constant slew-rate, the current dedicated to
I
Some technique are included in W83301DR-O to further reduce the total charging
Note that, too slow ramp-up rate is not recommended. If so, the state transition
COUT
= Iss x (Cout / Css)
7
Publication Release Date: Jul., 2002
W83301DR-O
Revision 1.0