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MAX22288

Home Bus System (HBS) Compatible Transceiver

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Detailed Description

The MAX22288 can be used in the Home Bus System (HBS), where power and data are carried on a single pair of wires.

The MAX22288 operates with data rates up to 200kbps for bus-powered applications. The MAX22288 is used in HBS

applications where external power supplies are sourced. In HBS applications where power is consumed, the MAX22088,

a HBS compatible transceiver with active inductor, can be used. Refer to the MAX22088 data sheet for more information.

The MAX22288 features dynamic cable termination, configurable receiver thresholds, and transmit driver slew rate

adjustment for better signal quality and flexible design.

Power Supply

The MAX22288 is powered by the external 5V (typ) supplied at VCC. An external inductor and coupling capacitors are

required to superimpose the data on the HBS cable.

Operation of MAX22288 Transceiver

The MAX22288 uses three pins for the logic interface: RST, DIN, and DOUT. AIO, BIO, and TERM are connected to the

HBS network. RST is the bus reset control input. Drive RST low to enable the transmitter on AIO and BIO. Drive RST

high to disable the transmitter. The MAX22288 HBS receiver is always enabled.

DIN is the logic input of the MAX22288. DOUT is the logic output. When DIN goes from high to low, the polarities of AIO

and BIO invert. When DIN goes from low to high, AIO and BIO are set to high-impedance (Figure 5).

DOUT asserts low when the leading edge of VAIO - VBIO crosses VTVL or -VTVL. DOUT is high-impedance when the

trailing edge of VAIO - VBIO crosses VTVT or -VTVT. See the Receiver Threshold Adjustment section for more information.

To improve signal quality, the MAX22288 features an internal sw

itch that connects TERM to AIO for 34μs (typ) after the

driver transitions to high-impedance. See the Dynamic Cable Termination section for more information.

For a typical data rate of 57.6kbps, the recommended value for coupling capacitors is 2.2µF (min).

RST

DIN

AIO

BIO

TERM

DOUT

SW OFF

SW ON

Figure 5. Operation of the MAX22288

MAX22191 Datasheet(PDF) 13 Page - Maxim Integrated Products