TPS2070, TPS2071

FOUR-PORT USB HUB POWER CONTROLLERS

SLVS287A – SEPTEMBER 2000 – REVISED FEBRUARY 2001

20

POST OFFICE BOX 655303

TYPICAL CHARACTERISTICS

Figure 36

100

50

0

6

6.5

7

7.5

150

200

SUPPLY CURRENT

vs

INPUT VOLTAGE

250

8

8.5

9

VI(VEXT) – Input Voltage – V

VI(BP) = 5 V,

EN_REG = LOW,

C(VCP) = 0.1 µF,

C(CP_P) = 0.01 µF,

TA = 25°C

Figure 37

2.75

2.7

2.65

2.6

–50

0

50

2.8

2.85

UNDERVOLTAGE LOCKOUT

vs

JUNCTION TEMPERATURE

2.9

100

150

TJ – Junction Temperature – °C

Start Threshold

Stop Threshold

APPLICATION INFORMATION

external capacitor requirements

A 0.1-

µF ceramic bypass capacitor and a 10-µF bulk capacitor between BP and AGND, close to the device, are

recommended. Similarly, a 0.1-

µF ceramic and a 68-µF bulk capacitor, from SP to AGND, and from VEXT to

AGND if an external 5-V LDO is required, are recommended because of much higher current in the self-powered

mode.

From each of the outputs (OUTx) to ground, a 33-

µF or higher valued bulk capacitor is recommended when the

output load is heavy. This precaution reduces power-supply transients. Additionally, bypassing the outputs with

a 0.1-

µF ceramic capacitor improves the immunity of the device to short-circuit transients.

An output capacitor connected between 3.3V_OUT and GND is required to stabilize the internal control loop.

The internal LDO is designed for a capacitor range of 4.7

µF to 33 µF with an ESR of 0.2 Ω to 10 Ω. Solid

tantalum-electrolytic, aluminum-electrolytic and multilayer ceramic capacitors are all suitable.

Ceramic capacitors have different types of dielectric material, each exhibiting different temperature and voltage

variations. The most common types are X5R, X7R, Y5U, Z5U, and NPO. The NPO type ceramic capacitors are

generally the most stable over temperature. However, the X5R and X7R are also relatively stable over

temperature (with the X7R being the more stable of the two) and are therefore acceptable for use. The Y5U and

Z5U types provide high capacitance in a small geometry, but exhibit large variations over temperature. For this

reason, the Y5U and Z5U are not generally recommended.