Analog Devices Inc./Maxim Integrated MAX1840EUB

Overview

MAX1840EUB from Maxim Integrated is a SIM/smart card level translator IC integrating two unidirectional level shifters (for CLK and RST), one bidirectional level shifter (for DATA/IO), ±10kV ESD protection on all card contacts, 1.0µA total quiescent supply current, and SHDN-controlled shutdown for safe card insertion/removal in GSM cellular handsets.

For engineers reviewing the MAX1840EUB datasheet, MAX1840EUB pinout, MAX1840EUB application, or MAX1840EUB equivalent, this device supports multivoltage SIM interfaces where DVCC (1.4V–5.5V) and VCC (1.7V–5.5V) may differ, delivers guaranteed 5MHz–20MHz CLK translation, maintains active low outputs during shutdown, and enables compliant GSM 11.11/11.12 smart card port design without external pull-ups.

Technical Context

The MAX1840EUB implements voltage-domain isolation between controller-side (DVCC/GND) and card-side (VCC/GND) logic using transfer-gate-based level shifting. It supports bidirectional data translation via open-drain IO with internal 10kΩ pull-up to VCC and open-drain DATA with 20kΩ pull-up to DVCC.

Its shutdown architecture actively pulls CLK, RST, and IO low when SHDN = GND, disconnects internal pull-ups, and reduces total supply current to 0.01µA. ESD protection meets ±10kV HBM on CLK, RST, IO, VCC, and GND - validated under powered, shutdown, and power-down states with 1µF VCC bypassing.

Key Specifications

Pinout & Package

MAX1840EUB is housed in a 10-pin µMAX package (3.0mm × 3.0mm, 1.09mm height), pin-compatible with industry-standard 10-lead µMAX footprint and half the area of 8-pin SO.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SIM/smart card level translation applications.

Compared with MAX1840EUB, MAX1841EUB adds push-pull data driving capability at the cost of losing SHDN control, while MAX3221EUE+ is functionally unrelated - making MAX1840EUB the only drop-in solution for GSM-compliant, low-power SIM translation with active shutdown.

Availability

MAX1840EUB is available at Aetrix Electronics and suitable for GSM handset design, smart card reader manufacturing, and SPI/MICROWIRE multivoltage interface development requiring stable component supply and long-term lifecycle support.

Supply support for MAX1840EUB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for automotive, industrial, communications, and consumer applications.

The MAX1840EUB belongs to Maxim's SIM/smart card interface product line, engineered specifically to simplify GSM-compliant, low-power, multivoltage smart card port implementation in space- and power-constrained portable electronics.

FAQ

What is the primary function of the MAX1840EUB in a GSM handset design?

The MAX1840EUB serves as a dedicated SIM/smart card level translator and ESD protector in GSM handsets. It shifts clock, reset, and bidirectional data signals between the controller-side DVCC (1.4V–5.5V) and card-side VCC (1.7V–5.5V), provides ±10kV ESD protection on all card-contact pins, and enables safe hot insertion/removal via SHDN-controlled shutdown. The MAX1840EUB eliminates need for external level shifters or TVS diodes while meeting GSM 11.11/11.12 specifications.

Does the MAX1840EUB require external pull-up resistors on the DATA or IO lines?

No, the MAX1840EUB integrates a 20kΩ pull-up resistor from DATA to DVCC and a 10kΩ pull-up resistor from IO to VCC. These internal resistors eliminate the need for external components in standard open-drain controller configurations. The MAX1840EUB datasheet confirms these values under Electrical Characteristics, and they are validated across temperature and voltage ranges - enabling simplified PCB layout and consistent signal rise times without layout-dependent variations.

How does the MAX1840EUB handle power sequencing during SIM card insertion and removal?

The MAX1840EUB uses its SHDN pin to enforce safe power sequencing: driving SHDN low actively pulls CLK, RST, and IO low and disconnects internal pull-ups, ensuring all card-contact pins remain ≤0.4V before insertion. This satisfies GSM 11.11 pre-insertion requirements. The MAX1840EUB also reduces total supply current to 0.01µA in shutdown, minimizing leakage during card swap. No external sequencing circuitry is needed - the MAX1840EUB handles it autonomously.

Can the MAX1840EUB translate signals when DVCC is lower than VCC (e.g., 1.8V controller to 3V SIM)?

Yes, the MAX1840EUB explicitly supports bidirectional level translation regardless of whether DVCC ≥ VCC or DVCC ≤ VCC. Its transfer-gate architecture allows valid operation with DVCC as low as 1.4V and VCC as high as 5.5V - including 1.8V-to-3V and 1.8V-to-5V configurations. The MAX1840EUB datasheet confirms this in the General Description and Detailed Description sections, and electrical characteristics (e.g., VOL, VOH) are specified across the full overlapping voltage range.

What is the maximum clock frequency supported by the MAX1840EUB, and under what conditions?

The MAX1840EUB supports up to 20MHz CLK frequency when VCC is 2.7V–5.5V and DVCC is 1.4V–2.7V; it supports up to 15MHz when VCC is 1.7V–3.6V and DVCC is 1.4V–2.25V. These limits ensure output duty cycle remains within 40%–60% under 50% CIN input with 5ns edge rates. The MAX1840EUB datasheet specifies these values in the Electrical Characteristics table under "Maximum CLK Frequency" with Notes 4 and 5 defining test methodology and waveform criteria.