Datasheet

IN
OUT
5V_DC/DC
5V_LDO
EN
19V
EN
DP
DM
OC
POWER Block
USB Host
Controller
I/O_EN
I/O_Sx
DM_OUT
DP_OUT
FAULT
EN
CTL1
CTL2
CTL3
STATUS
ILIM_SEL
Switches
Power
between LDO
and DC/DC
based on
/STATUS
ILIM_LO
ILIM_HI
DM_IN
DP_OUT
GND
VBUS
D-
D+
GND
USB
Connector
0011
55 mA ilimit
Applied
Hi
CASE I: System in S4 /S5 no Device Attached
TPS2543
Peripheral
Device
Not
Connected
DC-DC Disconnected/
Shut-Down
LDO Switched-In
Embedded
Controller
TPS2543
www.ti.com SLVSBA6 –FEBRUARY 2012
Load Detect
TPS2543 offers system designers unique power management strategy not available in the industry from similar
devices. There are two power management schemes supported by the TPS5243 via the STATUS pin, they are:
1. Power Wake (PW)
2. Port Power Management (PPM)
Either feature may be implemented in a system depending on power savings goals for the system. In general
Power Wake feature is used mainly in mobile systems like a notebook where it is imperative to save battery
power when system is in deep sleep (S4/S5) state. On the other hand Port Power Management feature would be
implemented where multiple charging ports are supported in the same system and system power rating is not
capable of supporting full charging on multiple ports simultaneously.
Power Wake
Goal of power wake feature is to save system power when system is in S4/S5 state. In S4/S5 state system is in
deep sleep and typically running of the battery; so every “mW” in system power savings will translate to
extending battery life. In this state the TPS2543 will monitor charging current at the OUT pin and provide a
mechanism via the STATUS pin to switch-out the high power DC-DC controller and switch-in a low power LDO
when charging current requirement is <45mA (typ). This would be the case when no peripheral device is
connected at the charging port or if a device has attained its full battery charge and draws <45mA.
As shown in below when system is in S4/S5 mode (0011 setting, see device truth table) and no device is
connected to the charging port (Case I) system runs off a 100mA LDO. Also note TPS2543 will automatically set
its ilimit to 55mA (typ) irrespective of ILIM_LO and ILIM_Hi setting.
Now when a device is attached (CASE II) and draws >55 mA of charging current the TPS2543 will hit its internal
current limit as the current drawn by the attached device will exceed the 55mA ilimit threshold. This will trigger
the device to assert STATUS to turn on the main power supply and discharge OUT for 310ms (typ) to allow the
main power supply to turn on. After the discharge the device will turn back on with current limit set by ILIM_HI. In
Case III as the attached device is being charged the TPS2543 will monitor its load current. STATUS remains
asserted until load current drops below 45mA (typ) for a continuous period of 15s indicating that the attached
device is fully charged. At this point STATUS de-asserts and ilimit is set back to 55mA as shown below.
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Product Folder Link(s): TPS2543