TPS2540 Datasheet, PDF (25/37 Pages) Texas Instruments – USB Charging Port Power Switch and Controller

TPS2540
TPS2541
www.ti.com
SLVSAG2 – OCTOBER 2010
Logic Control Modes
Both the TPS2540 and TPS2541 support the listed standards above for the SDP, CDP and DCP modes using
the CTL1, CTL2, and CTL3 logic I/O control pins, although their truth tables are different as shown below. The
different CTLx settings correspond to the different types of charge modes. Also, using the Auto-Detect Mode, the
Divider Mode or BC1.2 (draft) / YD/T 1591-2009 can be automatically selected without external user interaction.
NOTE
With the TPS2540, if the “000” mode is selected, the power switch will be turned off and
an output discharge resistor will be connected, while the data line switches will be turned
off.
CTL1
0
0
X
1
1
1
CTL2
0
X
1
0
0
1
Table 2. TPS2540 Control Truth Table
CTL3
0
1
0
0
1
1
MODE
OUT discharge, power switch OFF.
Dedicated charging port, auto-detect.
Standard downstream port, USB 2.0 Mode.
Dedicated charging port, BC1.2 (draft) only.
Dedicated charging port, Divider Mode only.
Charging downstream port, BC1.2 (draft).
CTL1
0
0
1
1
1
CTL2
0
1
0
1
1
Table 3. TPS2541 Control Truth Table
CTL3
X
X
X
0
1
MODE
Dedicated charging port, auto-detect.
Dedicated charging port, BC1.2 (draft).
Dedicated charging port, Divider Mode only.
Standard downstream port, USB 2.0 Mode.
Charging downstream port, BC1.2 (draft).
Output Discharge
To allow a charging port to renegotiate current with a portable device, TPS2540/41 uses the VBUS discharge
function. It proceeds by turning off the power switch while discharging OUT, then turning back ON the power
switch to reassert the OUT 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, a direct discharge control, DSC, is available with the TPS2541, while with the TPS2540, a
discharge 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 V_IN has been applied.
The TPS2540/41 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.
Copyright © 2010, Texas Instruments Incorporated
Product Folder Link(s): TPS2540 TPS2541
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