GL852 USB 2.0 MTT HUB Controller

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Figure 5.3 - RESET# (External Reset) setting and application

GL852 internally contains a power on reset circuit. The power on sequence is depicted in the next picture.

To fully control the reset process of GL852, we suggest the reset time applied in the external reset circuit

should longer than that of the internal reset circuit.

≒ 2.7 μs

Internal reset

External reset

Power good voltage, 2.5~2.8V

VCC(3.3V)

Figure 5.4 - Power on sequence of GL852

5.2.2 PGANG/SUSPND Setting

To save pin count, GL852 uses the same pin to decide individual/gang mode as well as to output the

suspend flag. The individual/gang mode is decided within 20us after power on reset. Then, about 50ms later,

this pin is changed to output mode. GL852 outputs the suspend flag once it is globally suspended. For

individual mode, a pull low resister greater than 100K

should be placed. For gang mode, a pull high

resister which greater than 100K

should be placed. In figure 5.6, we also depict the suspend LED

indicator schematics. It should be noticed that the polarity of LED must be followed, otherwise the suspend

current will be over spec limitation (2.5mA).