I(AUX) − Auxiliary Current − mA

175

200

225

250

275

300

325

0

200

400

600

800

1000

G012

RL = 100 kΩ

TJ = 25°C

VIN = 2.4 V

VIN = 3.3 V

VIN = 5.2 V

VIN = 4.75 V

VIN − Input Voltage − V

1250

1275

1300

1325

1350

1375

1400

1425

1450

3.25

3.75

4.25

4.75

5.25

G013

RL = 20 kΩ

TJ = 25°C

I(AUX) = 200 mA

I(AUX) = 500 mA

I(AUX) = 0 mA

I(AUX) = 400 mA

I(AUX) = 300 mA

VIN − Input Voltage − V

625

650

675

700

725

750

2.25

2.75

3.25

3.75

4.25

4.75

5.25

G014

RL = 40 kΩ

TJ = 25°C

I(AUX) = 500 mA

I(AUX) = 400 mA

I(AUX) = 300 mA

I(AUX) = 0 mA

I(AUX) = 200 mA

VIN − Input Voltage − V

175

200

225

250

275

300

325

2.25

2.75

3.25

3.75

4.25

4.75

5.25

G015

I(AUX) = 600 mA

I(AUX) = 500 mA

I(AUX) = 800 mA

I(AUX) = 1000 mA

I(AUX) = 0 mA

I(AUX) = 900 mA

I(AUX) = 700 mA

RL = 100 kΩ

TJ = 25°C

I(AUX) = 200 mA

I(AUX) = 400 mA

I(AUX) = 300 mA

TPS2500, TPS2501

SLVS886C – OCTOBER 2008 – REVISED AUGUST 2010

www.ti.com

Figure 16. USB Current-Limit Threshold vs IAUX,

Figure 17. USB Current-Limit Threshold vs VIN,

RILIM = 100 kΩ, TA = 25 °C

RILIM = 20 kΩ, TA = 25 °C

Figure 18. USB Current-Limit Threshold vs VIN,

Figure 19. USB Current-Limit Threshold vs VIN,

RILIM = 40 kΩ, TA = 25 °C

RILIM = 100 kΩ, TA = 25 °C

Accounting for Resistor Tolerance in the USB Switch Current-Limit Accuracy

The previous sections described the selection of RILIM, given certain application requirements and the importance

of understanding the current-limit threshold tolerance. The analysis focused only on the TPS2500 performance

and assumed an exact resistor value. However, resistors sold in quantity are not exact and are bounded by an

upper and lower tolerance centered around a nominal resistance. The additional RILIM resistance tolerance

directly affects the current-limit threshold accuracy at a system level. Table 3 shows a process that accounts for

18

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