Low-Voltage SIM/Smart Card

Level Translators in µMAX

6

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Detailed Description

The MAX1840/MAX1841 provide the necessary level

translation for interfacing with SIMs and smart cards in

multivoltage systems. These devices operate with logic

supply voltages between +1.4V and +5.5V on the con-

is 1µA while operating in an idle state (see Electrical

Characteristics). Figure 1 shows the MAX1840/MAX1841

test circuit. The Typical Application Circuit appears at the

end of this data sheet.

Level Translation

The MAX1840/MAX1841 provide level translators for a

clock input, a reset input, and a bidirectional data IO.

The clock and reset inputs (CIN and RIN) are level shift-

nected to an open-drain controller output, DATA and IO

provide bidirectional level translation. All level transla-

MAX1840/MAX1841 contain internal pull up resistors

controller outputs, see the Data Driver section for bidi-

rectional data translation.

Data Driver (MAX1841 Only)

When using a microcontroller (µC) without an open-drain

output, use the data driver (DDRV) input to send data to

the SIM/smart card, while DATA provides the controller-

side output for bidirectional data transfer. When not

rent.

Shutdown Mode

For the MAX1840, drive SHDN low to activate shut-

operation. To allow for card insertion and removal, shut-

down mode actively pulls CLK, RST, and IO low; it also

disconnects the internal 10k

to prevent excessive current draw. Shutdown mode

0.01µA.

SIM/Smart Card Insertion/Removal

The SIM/smart card specifications require that the card-

prior to inserting the SIM/smart card. For applications

using the MAX1686H (Figure 3), the easiest way to

achieve this is by shutting down the MAX1686H or by

driving SHDN (MAX1840 only) low. If specific sequenc-

ing is desired, pull IO low by driving either DATA or

DDRV (MAX1841 only) low, and pull CLK and RST low

by driving CIN and RIN low, respectively.

ESD Protection

As with all Maxim devices, ESD-protection structures on

all pins protect against ESDs encountered during han-

dling and assembly. For further protection during card

insertion and removal, the pins that connect to the card

tion against ±10kV of ESD. The ESD structures with-

stand high ESD in all states: normal operation,

shutdown, and power-down. After an ESD event, the

MAX1840/MAX1841 continue working without latchup.

exceed ±10kV ESD specifications.

ESD Test Conditions

ESD performance depends on a variety of conditions.

Contact Maxim for a reliability report documenting test

setup, test methodology, and test results.

Applications Information

SIM/Smart Card Interface

To provide 5V when interfacing with a 5V SIM/smart card,

+3V systems require a DC-DC converter. The MAX1686H

+5V regulating charge pump for SIM cards provides

GND

IO

CLK

RST

+1.8V

+1.8V,

+3.0V, OR

+5.0V

30pF

30pF

30pF

30pF

MAX1840

MAX1841

SHDN*

RIN

CIN

DDRV*

DATA

SHDN FOR MAX1840 ONLY;

DDRV FOR MAX1841 ONLY.

*

NOTE: ALL CAPACITANCES INCLUDE CAPACITIVE LOADS OF

TEST PROBES AND BOARD LAYOUT.

Figure 1. MAX1840/MAX1841 Test Circuit