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SYSRST

OC

FUNCTIONAL TRUTH TABLES

Truth Table for Voltage Outputs

Truth Table for Logic Outputs

TPS2231

TPS2236

SLVS536B – JULY 2004 – REVISED JANUARY 2005

Detailed Pin Descriptions (continued)

This input is driven by the host system and directly affects PERST. Asserting SYSRST (logic low) forces PERST

to assert. RCLKEN is not affected by the assertion of SYSRST. SYSRST has an internal pullup connected to

AUXIN.

This pin is an open-drain output. When any of the three power switches (AUX, 3.3V, and 1.5V) is in an

overcurrent condition, OC is asserted (logic low) by an internal discharge FET with a deglitch delay. Otherwise,

the discharge FET is open, and the pin can be pulled up to a power supply through an external resistor.

LOGIC INPUTS

AUXIN

3.3VIN

1.5VIN

SHDN

STBY

AUXOUT

3.3VOUT

1.5VOUT

Off

x

x

x

x

x

Off

Off

Off

OFF

On

x

x

0

x

x

GND

GND

GND

Shutdown

On

x

x

1

x

1

GND

GND

GND

No Card

On

On

On

1

0

0

On

Off

Off

Standby

On

On

On

1

1

0

On

On

On

Card Inserted

(1)

For input voltages, On means the respective input voltage is higher than its turnon threshold voltage; otherwise, the voltage is Off (for

AUX input,Off means the voltage is close to zero volt).

(2)

For output voltages, On means the respective power switch is turned on so the input voltage is connected to the output; Off means the

power switch and its output discharge FET are both off; GND means the power switch is off but the output discharge FET is on so the

voltage on the output is pulled down to 0 V.

(3)

Mode assigns each set of input conditions and respective output voltage results to a different name. These modes are referred to as

input conditions in the following Truth Table for Logic Outputs.

(4)

CP = CPUSB and CPPE– equal to 1 when both CPUSB and CPPE signals are logic high, or equal to 0 when either CPUSB or CPPE is

low.

INPUT CONDITIONS

LOGIC OUTPUTS

MODE

SYSRST

PERST

OFF

Shutdown

X

X

0

0

No Card

Standby

0

Hi-Z

0

1

0

0

0

0

Card Inserted

1

Hi-Z

1

1

1

0

0

0

(1)

RCLKEN as a logic input in this column. RCLKEN is an I/O pin and it can be driven low externally, left open, or connected to

high-impedance terminals, such as the gate of a MOSFET. It must not be driven high externally.

(2)

RCLKEN as a logic output in this column.

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