USB5744-ISLASH2G datasheet(35/49 Pages) MICROCHIP

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 2015-2016 Microchip Technology Inc.

DS00001855D-page 35

USB5744

9.6

AC Specifications

This section details the various AC timing specifications of the device.

9.6.1

POWER SUPPLY AND RESET_N SEQUENCE TIMING

Figure 9-2 illustrates the recommended power supply sequencing and timing for the device. VDD33 should rise after or

at the same rate as VDD12. Similarly, RESET_N and/or VBUS_DET should rise after or at the same rate as VDD33.

VBUS_DET and RESET_N do not have any other timing dependencies.

9.6.2

POWER-ON AND CONFIGURATION STRAP TIMING

Figure 9-3 illustrates the configuration strap valid timing requirements in relation to power-on, for applications where

RESET_N is not used at power-on. In order for valid configuration strap values to be read at power-on, the following

timing requirements must be met. The operational levels (Vopp) for the external power supplies are detailed in Section

9.2, "Operating Conditions**," on page 31.

Device configuration straps are also latched as a result of RESET_N assertion. Refer to Section 9.6.3, "Reset and Con-

figuration Strap Timing" for additional details.

FIGURE 9-2:

POWER SUPPLY AND RESET_N SEQUENCE TIMING

TABLE 9-5:

POWER SUPPLY AND RESET_N SEQUENCE TIMING

Symbol

Description

Min

Typ

Max

Units

tVDD33

VDD12 to VDD33 rise time

treset

VDD33 to RESET_N/VBUS_DET rise time

FIGURE 9-3:

POWER-ON CONFIGURATION STRAP VALID TIMING

TABLE 9-6:

POWER-ON CONFIGURATION STRAP LATCHING TIMING

Symbol

Description

Min

Typ

Max

Units

tcsh

Configuration strap hold after external power supplies at opera-

tional levels

1ms

VDD12

VDD33

RESET_N/

VBUS_DET

All External

Power Supplies

Vopp

Configuration

Straps

tcsh

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