000-000C55545-101

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SLGC55545

Output Discharge

To allow a charging port to renegotiate current with a portable device, SLGC55545 uses the VBUS discharge function. It proceeds

by turning off the power switch while discharging VOUT, then turning back ON the power switch to reassert the VOUT voltage.

This discharge function is automatically applied when a change at the CTLx lines results in any of the following mode transitions.

•

Any transition to and from CDP

•

Any transition to and from SDP

In addition to this, can be achieved using the mode “000”.

Overcurrent Protection

When an over-current condition is detected, the device maintains a constant output current and reduces the output voltage

accordingly. Two possible overload conditions can occur. In the first condition, the output has been shorted before the device is

enabled or before VIN has been applied.

The SLGC55545 senses the short and immediately switches into a constant-current output. In the second condition, a short or

an overload occurs while the device is enabled. At the instant the overload occurs, high currents may flow for nominally one to

two microseconds before the current-limit circuit can react. The device operates in constant-current mode after the current-limit

circuit has responded. Complete shutdown occurs only if the fault is present long enough to activate thermal limiting. The device

will remain off until the junction temperature cools approximately 10°C and will then re-start. The device will continue to cycle

on/off until the over-current condition is removed.

FAULT# Response

The FAULT# open-drain output is asserted (active low) during an over-temperature or current limit condition. The output remains

asserted until the fault condition is removed. The SLGC55545 is designed to eliminate false FAULT# reporting by using an internal

deglitch circuit for current limit conditions without the need for external circuitry. This ensures that FAULT# is not accidentally

asserted due to normal operation such as starting into a heavy capacitive load. Over-temperature conditions are not deglitched

and assert the FAULT# signal immediately.

Undervoltage Lockout (UVLO)

The undervoltage lockout (UVLO) circuit disables the power switch until the input voltage reaches the UVLO turn-on threshold.

Built-in hysteresis prevents unwanted oscillations on the output due to input voltage drop from large current surges.

Thermal Sense

The SLGC55545 protects itself with two independent thermal sensing circuits that monitor the operating temperature of the power

distribution switch and disables operation if the temperature exceeds recommended operating conditions. The device operates

in constant-current mode during an over-current condition, which increases the voltage drop across power switch. The power

dissipation in the package is proportional to the voltage drop across the power switch, so the junction temperature rises during

an over-current condition. The first thermal sensor turns off the power switch when the die temperature exceeds 135°C and the

part is in current limit. The second thermal sensor turns off the power switch when the die temperature exceeds 155°C regardless

of whether the power switch is in current limit. Hysteresis is built into both thermal sensors, and the switch turns

on after the device has cooled by approximately 10°C. The switch continues to cycle off and on until the fault is removed. The

open-drain false reporting output FAULT# is asserted (active low) during an over-temperature shutdown condition.

Power Wake

The SLGC55545 monitors charging current at the VOUT pin and provide sa mechanism via the STATUS# pin to switch out the

high power DC-DC and switch to a low power LDO when charging current requirement is < 45 mA (typ). This saves system power

in S4/S5 state while the port has no peripheral device connected. The function is specified in the truth table setting “0011”

Power Management

When a connected peripheral device request high current charge for their battery, the system may not be able to support to

enough current for every USB port. In this situation, the SLGC55545 supports a port power management function to help the

system designer to control their USB port power. STATUS# trip point is based on ILIM_L current limit value to set the point. When

a connected peripheral device requires port power charge current higher than ILIM_L+60mA 200ms then the STATUS# pin will

automatically output LOW to let system know. When the charge current is below ILIM_L+60mA 3s then STATUS# return back to

HIGH. This function works via truth table setting “0111” DCP_Auto mode and “1111” CDP mode.