TPS66021 datasheet(13/38 Pages) TI1

13 / 38 page

TPS66020, TPS66021

www.ti.com

SLVSEW8 – AUGUST 2019

Product Folder Links: TPS66020 TPS66021

Submit Documentation Feedback

Feature Description (continued)

8.3.1.1 PP5V Current Limit

The current through PP5V to VBUS current limit may be dynamically selected to support 1.5-A or 3-A operation

via EN0 and EN1. An external resistance to GND on IREF terminal is required to set the bias current for accurate

current limit operation.

Under overload conditions, the internal current-limit regulator limits the output current to the selected current limit

setting, ILIM_PP5V, where ILIM_PP5V is ILIM_PP5V_1P5 or ILIM_PP5V_3P0, as shown in the Electrical Characteristics. When

an overload condition is present, the device maintains a constant output current, with the output voltage

determined by (ILIM_PP5V x RLOAD ). Two possible overload conditions can occur. The first overload condition

occurs when either: 1) PP5V input voltage is first applied, PP5V source path is enabled (EN1_EN0 = 10b or

EN1_EN0 = 11b), and a short circuit is presented (load which draws IOUT > ILIM_PP5V), or 2) PP5V input voltage is

present and the PP5V source path is enabled into a short circuit. The output voltage is held near zero potential

with respect to ground and the TPS6602x ramps the output current to ILIM_PP5V. The TPS6602x limits the current

to ILIM_PP5V until the overload condition is removed or the device begins to thermal cycle. This is demonstrated in

where the device was enabled into a short, and subsequently cycles current off and on as the thermal protection

engages.

The second condition is when an overload occurs while the PP5V source path is enabled and fully turned on.

The device responds to the overload condition within time tOS_PP5V (see Figure 1) when the specified overload

(per Electrical Characteristics) is applied. The response speed and shape vary with the overload level, input

circuit and rate of application. The current-limit response varies between simply settling to ILIM_PP5V or turning off

and a controlled return to ILIM_PP5V. Similar to the previous case, the TPS6602x limits the current to ILIM_PP5V until

the overload condition is removed or the device begins to thermal cycle. The TPS6602x thermal cycles if an

overload condition is present long enough to activate thermal limiting in any of the above cases. This is due to

the relatively large power dissipation [(VPP5V – VVBUS) x ILIM_PP5V] elevating the junction temperature. The PP5V

source path turns off when its temperature reaches its thermal shutdown temperature of TSD_PP5V_R while in

current limit. The PP5V source path remains off until its temperature cools to TSD_PP5V_F and then re-enables

automatically.

8.3.1.2 PP5V Reverse Current Protection (RCP)

When the PP5V power path is enabled, the RCP circuitry monitors the voltage across the path. If the RCP

monitor detects VVBUS - VPP5V ≥ VRCP_THRES_PP5V, the PP5V path will be disabled preventing additional current

flow from VBUS to PP5V. The power path will be completely disabled and remain disabled as long as the RCP

condition persists. After the RCP event, the PP5V path will automatically re-enable. FLT is asserted when a

reverse current protection event occurs on the PP5V path.

8.3.2 20-V Sink (PPHV Power Path)

The PPHV path is a Sink only path, providing power from the VBUS terminal to the PPHV terminal when

enabled. The PPHV power path uses two back-to-back N-channel MOSFETs, and blocks current in both

directions when the power path is disabled.

8.3.2.1 PPHV Soft Start

The TPS6602x PPHV power path has soft start circuitry to control in-rush current when the PPHV power path is

enabled. DC loading should be minimized during soft start since the PPHV path may experience high power

dissipation especially at higher VBUS voltages. This may lead to a PPHV overtemperature protection event.

8.3.2.2 PPHV Reverse Current Protection (RCP)

When the PPHV power path is enabled, the RCP circuitry monitors the voltage across the path. If the RCP

monitor detects VPPHV - VVBUS ≥ VRCP_THRES_PPHV, the PPHV path will be disabled preventing additional current

flow from PPHV to VBUS. The power path will be completely disabled and remain disabled as long as the RCP

condition persists. After the RCP event, the PPHV path will automatically re-enable. FLT is not asserted when a

reverse current protection event occurs on the PPHV path.

TPS66021 Scheda tecnica(PDF) 13 Page - Texas Instruments

TPS66021 Scheda tecnica(HTML) 13 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Scheda tecnica Scarica

Link URL