Datasheet

USB251xB/xBi
DS00001692C-page 36  2010 - 2015 Microchip Technology Inc.
5.5.1.1 RESET_N for Strapping Option Configuration
Note 5-1 10 ms for hubs, 50 ms for root ports.
FIGURE 5-1: RESET_N TIMING FOR DEFAULT CONFIGURATION
Name Description MIN TYP MAX Units
t1 RESET_N asserted 1 s
t2 CFG_SEL[1:0] setup time 16.7 ns
t3 CFG_SEL[1:0] hold time 16.7 1400 ns
t4 Hub outputs driven to inactive logic states 1.5 2
s
t5 USB attach (see notes) 3
s
t6 Host acknowledges attach and signals USB reset 100 ms
t7 USB_RESET Host
Defined
ms
t8 USB_RESET State Note 5-1 ms
t9 USB Reset Recovery 10 ms
Note:
• When in bus-powered mode, the hub and its associated circuitry must not consume more than 100 mA from the
upstream USB power source during t1+t5.
• All power supplies must have reached the operating levels mandated in Section 6.0, "DC Parameters", prior to
(or coincident with) the assertion of RESET_N.
t1
t4
t5
t6
t7 t8
valid driven by hub if strap is an output
RESET_N
VSS
CFG_SEL[2:0]
VSS
Hardware
reset asserted
Read
CFG_SEL[1:0]
Drive strap
outputs to
inactive levels
Attach USB
upstream
Attach
Debounce
Interval
USB_RESET
USB_RESET
State
t2
t3
don’t care
don’t care
USB Reset
Recovery
t9