Complete 230kbps, 2.7V to 5.25V

Serial Interface for Notebook Computers

6

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_______________Detailed Description

The MAX562 has three sections: the charge-pump voltage

converter, the drivers (transmitters), and the receivers.

Charge-Pump Voltage Converter

The charge-pump voltage converter is used to produce a

positive and a negative supply to drive the transmitters. The

positive voltage (V+) is generated by a regulated charge

pump working as either a doubler or a tripler (depending on

Typical Operating Circuit). The negative voltage (V-) derives

from V+ using a simple charge-pump inverter that employs

capacitors C2 and C4.

These charge-pump converters are regulated to give output

voltages of +5.8V and -5.2V. Having regulated supplies

generated on-chip makes the MAX562's performance insen-

ing changes, and operating temperature changes.

When

SHDN is low, the charge pumps are disabled, V+ is

GND.

EIA/TIA-562 Drivers

The driver output voltage is guaranteed to meet the ±3.7V

EIA/TIA-562 specification over the full range of operating

temperatures and voltages, when each transmitter is

loaded with up to 3k

Ω and operated up to 230kbps (see

Typical Operating Characteristics). The typical driver out-

put voltage swing exceeds ±4V with a 3k

Ω load on all

transmitter outputs. The open-circuit output voltage swing

is typically from (V+ - 0.7V) to (V- + 0.7V). Output swing is

pumps are regulated.

Input thresholds are CMOS and TTL compatible. Connect

When

SHDN is low, the driver outputs are off and their leak-

age currents are less than 10µA, even if the transmitter

outputs are back-driven between -7V and +15V. Taking

SHDN low does not disable the receivers.

When

SHDN and EN are both low, the entire chip is

disabled and all outputs are high impedance. Power

consumption is lowest in this condition. Exiting shutdown

SHDN

+3V

0V

+3V

-3V

0V

A. TIMING DIAGRAM

1 OR 0

3k

50pF

B. TEST CIRCUIT

TRANSMITTER

OUTPUTS

Figure 3. Transmitter-Output Disable Timing

EN

1k

150pF

A. TEST CIRCUIT

B. ENABLE TIMING

EN INPUT

RECEIVER

OUTPUTS

+3V

0V

EN

RECEIVER

OUTPUTS

EN

+3V

0V

EN INPUT

C. DISABLE TIMING

R_

Figure 4. Receiver-Output Enable and Disable Timing