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3. TECHNICAL BRIEF
Figure 3-15. BLOCKDIAGRAM
Cradle Charge Current
The cradle charge current is enabled by the EN pin only, the USBON pin has no control on the cradle
charge current. The cradle charge current is programmed with the external resistor connected
between the ICDL pin and the GND pin. The current can be calculated with one of the equations given
in the ICDL pin description. Two equations are used for the cradle current calculation, each
corresponds to a different range of currents. The typical rDS(ON) of the P-channel MOSFET for the
CRDL input is 600mΩ at room temperature. When the head room between the input and output
voltages is small, the actual charge current, similar to the USB case, could be limited by the rDS(ON).
On the other hand, if the head room between the input and output voltages is large, the charge current
may be limited by the thermal foldback threshold.
Floating Charge Voltage
The floating voltage during the constant voltage phase is 4.2V. The floating voltage has an 1%
accuracy over the ambient temperature range of -40˚C to 70˚C.
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