USB2514 datasheet(14/57 Pages) MICROCHIP

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USB251xB/xBi

DS00001692C-page 14

 2010 - 2015 Microchip Technology Inc.

3.3.1

CONFIGURING THE STRAP PINS

If a pin's strap function is enabled thru the hub configuration selection, (Table 5-1, “Initial Interface/Configuration

Options,” on page 19) the strap pins must be pulled either high or low using the values provided in Table 3-3. Each strap

option is dependent on the pin’s buffer type, as outlined in the sections that follow.

SUSP_IND/

I/O

Active/Suspend Status LED: indicates USB state of the hub.

Negated = unconfigured; or configured and in USB suspend

Asserted = hub is configured and is active (i.e., not in suspend)

LOCAL_PWR/

Local Power: detects availability of local self-power source.

Low = self/local power source is NOT available (i.e., the hub gets all power from

the upstream USB VBus)

High = self/local power source is available

NON_REM0

Non-Removable 0 Strap Option: when enabled by package and configuration

settings (see Table 5-1 on page 19), this pin will be sampled (in conjunction with

NON_REM[1]) at RESET_N negation to determine if ports [x:1] contain

permanently attached (non-removable) devices:

Note:

When implementing an external LED on this pin, the active state is

outlined below and detailed in Section 3.3.1.3, on page 15.

NON_REM[1:0] = 00 : all ports are removable; LED is active high

NON_REM[1:0] = 01 : port 1 is non-removable; LED is active low

NON_REM[1:0] = 10 : ports 1 and 2 are non-removable; LED is active high

NON_REM[1:0] = 11 : (when available) ports 1, 2, and 3 are non-removable; LED

is active low

TEST

IPD

Test Pin: treat as a no connect pin or connect to ground. No trace or signal should

be routed or attached to this pin.

POWER, GROUND, and NO CONNECTS

CRFILT

VDD Core Regulator Filter Capacitor: this pin can have up to a 0.1

F low-ESR

capacitor to VSS, or be left unconnected.

VDD33

3.3 V Power

VDDA33

3.3 V Analog Power

PLLFILT

PLL Regulator Filter Capacitor: this pin can have up to a 0.1

F low-ESR capacitor

to VSS, or be left unconnected.

VSS

Ground Pad/ePad: the package slug is the only VSS for the device and must be

tied to ground with multiple vias.

No Connect: no signal or trace should be routed or attached to all NC pins.

TABLE 3-3:

STRAP OPTION SUMMARY

Strap Option

Resistor Value

Buffer Type

Notes

Non-Removable

47 - 100 k



I/O

Internal Pull-Down

10 k



IPD

• Only applicable to port power pins

• Contains a built-in resistor

LED

47 - 100 k



I/O

TABLE 3-2:

USB251XB/XBI PIN DESCRIPTIONS (CONTINUED)

Symbol

Buffer

Type

Description

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