Slave Address

0

1

1

1

1

0

IRQ

R/W

TXS02326

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SCES795B – SEPTEMBER 2010 – REVISED NOVEMBER 2010

BASIC DEVICE OPERATION

two SIM card slots and the SIM/UICC interface of the baseband. The device uses VBAT and VDDI/O as supply

voltages. The supply voltage for each SIM card is generated by an on-chip low drop out regulator. The interface

between the baseband and the TXS02326 is reference to VDDIO while the interface between the TXS02326 and

the SIM card is referenced to the LDO output of either VSIM1 or VSIM2 depending on which slot is being

selected. The VDDIO on the baseband side normally does not exceed 1.8V, thus voltage level shifting is needed

to support a 3V SIM/UICC interface (Class B).

The TXS02326 has two basic states, the reset and operation state. The baseband utilizes information in the

status registers to determine how to manipulate the control registers to properly switch between two SIM cards.

These fundamental sequences are outlined below and are to help the user to successfully incorporate this device

into the system.

DEVICE ADDRESS

The address of the device is shown below:

Address Reference

IRQ@ Reset

R/W

Slave Address

0

0 (W)

120 (decimal), 78(h)

0

1 (R)

121 (decimal), 79(h)

1

0 (W)

122 (decimal), 7A(h)

1

1 (R)

123 (decimal), 7B(h)

RESET STATE

In the reset state the device settings are brought back to their default values and any SIM card that has been

active is deactivated. After reset, neither of the UICC/SIM interfaces is selected. The active pull-downs at the

UICC/SIM interface are automatically activated. To ensure the system powers up in an operational state, device

uses an internal 32 KHz clock for internal timing generation. After power up, the system has the option to

continue to utilize the internal clock or select an external clock source. This clock source is selectable by the

•

Power up the TXS02326 by asserting VBAT to enter the operation state

•

RESET summary:

•

Any pending interrupts are cleared

•

•

BSI and SDN counter value in the registers are set to four clock cycles or “0000 0100”

•

Both on chip regulators are set to 1.8V and disabled

•

All SIM1 and SIM2 signals are pulled to GND

Copyright © 2010, Texas Instruments Incorporated

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Product Folder Link(s): TXS02326