SSI America EPS2U Control and Indicator Functions, Pson#, Pson # = Low Pson # = Open or High

SSI

EPS2U Power Supply Design Guide, V2.1

8Control and Indicator Functions

The following sections define the input and output signals from the power supply. Signals that can be defined as low true use the following convention:

signal# = low true

8.1PSON#

STATUS

Required

The PSON# signal is required to remotely turn on/off the power supply. PSON# is an active low signal that turns on the +3.3 V, +5 V, +12 V, and -12 V power rails. When this signal is not pulled low by the system, or left open, the outputs (except the +5 VSB and Vbias) turn off. This signal is pulled to a standby voltage by a pull-up resistor internal to the power supply. Refer to Figure 3 for timing diagram.

	Table 28: PSON# Signal Characteristic
Signal Type		Accepts an open collector/drain input from the system.
		Pull-up to VSB located in power supply.
PSON# = Low			ON
PSON# = Open or High			OFF
		MIN		MAX
Logic level low (power supply ON)		0 V		1.0 V
Logic level high (power supply OFF)		2.0 V		5.25 V
Source current, Vpson = low				4 mA
Power up delay:	Tpson_on_delay	5 ms		400 ms
PWOK delay:	T pson_pwok			50 ms

Disabled

Enabled

Hysteresis ≥ 0.3V and/or other de-bounce method

≤ 1.0 V	≥ 2.0 V
PS is	PS is
enabled	disabled

0V 1.0V 2.0V 5.25V

Figure 4: PSON# Signal Characteristics

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