ACT510x

Rev 1.0, 04-Apr-2018

13

VOUT[10:0] voltage register. The ramp rate the output changes can be controlled by the OUTPUT_SLEW[1:0] register. This

allows the output to conform to QC2.0/QC3.0/4.0/USB PD functions for higher output voltages.

If external feedback is used, the reference voltage on FB is 2V. The COMP pin is used for the output compensation.

5.1. Enable Delay

Once the condition has the valid conditions for startup, the Enable Delay timer is enabled. The timer options allow an

immediate startup, or to wait between 200msec and 1sec before enables the converter. This timing is controlled by the

EN_DLY[1:0] register.

5.2. Mode Soft Start

After the Enable Delay has completed, the device starts the output using a soft start function programmable by the SS[1:0]

Register. The time is independent of the output voltage setting if using internal feedback and or resistor settings when using

external feedback.

5.3. Constant Current Output Regulation

After soft start is completed, the device monitors the current on sense resistor (OSRP and OSRN) to provide constant

current regulation. When the output current exceeds threshold the value configured by the OLIM Pin and CC Register, the

switching converter will regulate the maximum current in a “constant current” mode. In this case, the output voltage may

drop. Constant current mode can be monitored in real time using the read only Output_CC Register 0x20 [5].

The current can be controlled with the external resistor on the OLIM pin and by the CC [6:0] Register 0x17 [6:0]. Current is

adjustable as a percentage of the full current level set by the OLIM resistor.

OSRN

OSRP

VOUT

OLIM

2V

+

+

-

-

VBAT

Figure 5: Charge Current Sensing and Current Limit Setting

This voltage on the OLIM pin is calculated by:

Equation 1

The voltage on this pin is regulated and clamped at 2V. The OLIM pin can also be used to monitor input current .The voltage

on OLIM pin is proportional to the charge current.

If the output drops below 2.72V, a fault on the output is assumed, and the converter will disable and wait 3 seconds in the

HICCUP state. After 3 seconds, the device will return to the Reset state and attempt to restart the output. If a short or high

current fault is present, it will cycle again through the states until the fault is removed.

5.4. Input Current Regulation

ACT510x monitors the current on input side sense resistor (ISRP and ISRN) to provide a current limit from the input. When

the input current exceeds threshold the value configured by the ILIM Pin and INPUT_ILIM Register 0x10 [3:2], the switching

converter will regulate the output current in a “constant current” mode. In this case, the output voltage may drop. Input

constant current mode can be monitored in real time using the read only INPUT_CC Register 0x20 [6].