Detailed Description

The MAX9972 is a four-channel, pin-electronics IC for

automated test equipment that includes, for each chan-

nel, a three-level pin driver, a window comparator, a

passive load, and a Kelvin instrument connection

(Figure 1). All functions feature a -2.2V to +5.2V operat-

ing range and the drivers include both high-impedance

and active-termination (3rd-level drive) modes. The

comparators feature programmable output voltages,

allowing optimization for different CMOS interface stan-

dards. The loads have selectable output resistance for

optimizing DUT current loading. The Kelvin paths allow

accurate connection of an instrument with ±25mA

source/sink capability. Additionally, the MAX9972 offers

a low-leakage mode that reduces DUT_ leakage cur-

rent to less than 20nA.

Each of the four channels feature single-ended CMOS-

compatible inputs, DATA_ and RCV_, for control of the

driver signal path (Figure 2). The MAX9972 modal

operation is programmed through a 3-wire, low-voltage

CMOS-compatible serial interface.

Output Driver

The driver input is a high-speed multiplexer that selects

one of three voltage inputs: DHV_, DLV_, or DTV_. This

switching is controlled by high-speed inputs DATA_ and

RCV_, and mode-control bit TERM (Table 1). DATA_

and RCV_ are single-ended inputs with threshold levels

pendently generated to minimize crosstalk.

DUT_ can be toggled at high speed between the buffer

output and high-impedance mode, or it can be placed

into low-leakage mode (Figure 2, Table 1). High-speed

input RCV_ and mode-control bits TERM and LLEAK

control these modes. In high-impedance mode, the

bias current at DUT_ is less than 2µA over the -2.2V to

+5.2V range, while the node maintains its ability to

track high-speed signals. In low-leakage mode, the

bias current at DUT_ is further reduced to less than

20nA, and signal tracking slows.

The nominal driver output resistance is 50Ω. Custom

resistance values from 45Ω to 51Ω are possible; con-

sult factory for further information.

Quad, Ultra-Low-Power, 300Mbps ATE

Drivers/Comparators

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17

Table 1. Driver Channel Control Signals

EXTERNAL

CONNECTIONS

INTERNAL

CONTROL BITS

RCV_

DATA_

TERM

LLEAK

DRIVER

OUTPUT

DRIVER

MODE

0

0

X

0

DUT_ = DLV_

Drive

0

1

X

0

DUT_ = DHV_

Drive

1X

0

0

High

Impedance

Receive

1

X

1

0

DUT_ = DTV_

Receive

X

X

X

1

Low Leak

Low

Leakage

MAX9972

DLV_

DHV_

DTV_

DATA_

RCV_

TERM

BUFFER

50

Ω

DUT_

0

0

0

1

1

COMPARATORS

AND LOAD

LLEAK

HIGH

IMPEDANCE

Figure 2. Multiplexer and Driver Channel