DIO74557S

Version 1.1, May 2024

www.dioo.com

© 2024 DIOO MICROCIRCUITS CO., LTD.

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1. Pin Assignment and Functions

Figure 1. QFN1.8*1.4-10 (Top view)

Pin Name

Description

RST_HOST

Reset input from the host controller.

VCCA

Supply voltage for the host controller side input/output pins (CLK_HOST, RST_HOST, IO_HOST).

The VCCA voltage ranges from 1.08 V to 1.95 V. This pin should be bypassed with a 0.1 μF ceramic

capacitor close to the pin.

RST_SIM

Reset the output pin for the SIM card. This pin is pulled low during shutdown through a 450 Ω

resistor.

CLK_HOST

Clock input from the host controller.

GND

Ground. This pin is the ground reference for the integrated circuit and associated signals.

CLK_SIM

Clock output pin for the SIM card. This pin is pulled low during shutdown through a 450 Ω resistor.

IO_HOST

Host controller bidirectional data input/output. The host output must be on an open-drain driver.

VCCB

SIM card supply voltage. When VCCB is below the VCCB_DIS, the device is disabled. The VCCB voltage

ranges from 1.65 V to 3.6 V. This pin should be bypassed with a 0.1 μF ceramic capacitor close to

the pin.

IO_SIM

SIM card bidirectional data input/output. The SIM card output must be on an open-drain driver.

This pin is pulled low during shutdown through a 450 Ω resistor.

EN

Enable pin. This pin should be HIGH (VCCA) for normal operation, and LOW to help avoid race

conditions specifically during the shutdown sequence.