Quad, Ultra-Low-Power, 300Mbps ATE

Drivers/Comparators

18

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Comparators

The MAX9972 provides two independent high-speed

comparators for each channel. Each comparator has

one input connected internally to DUT_ and the other

input connected to either CHV_ or CLV_ (see Figure 1).

Comparator outputs are a logical result of the input

conditions, as indicated in Table 2.

The comparator output voltages are easily interfaced to a

wide variety of logic standards. Use buffered inputs

COMPHI and COMPLO to set the high and low output

voltages. For correct operation, COMPHI should be

greater than or equal to COMPLO. The comparator 50Ω

output impedance provides source termination (Figure 3).

Passive Load

The MAX9972 channels each feature a passive load

consisting of a buffered input voltage, LDV_, connected

to DUT_ through two resistive paths (Figure 1). Each

path connects to DUT_ individually by a switch con-

trolled through the serial interface. Programming

options include none (load disconnected), either, or

both paths connected. The loads facilitate fast

open/short testing in conjunction with the comparator,

and pullup of open-drain DUT_ outputs.

Parametric Switches

Each of the four MAX9972 channels provides force-

and-sense paths for connection of a PMU or other DC

resource to the device-under-test (Figure 1). Each

force-and-sense switch is independently controlled

though the serial interface providing maximum applica-

tion flexibility. PMU_ and DUT_ are provided on sepa-

rate pins allowing designs that do not require the

parametric switch feature to avoid the added capaci-

tance of PMU_. It also allows PMU_ to connect to DUT_

either directly or with an impedance-matching network.

Low-Leakage Mode, LLEAK

Asserting LLEAK through the serial port places the

MAX9972 into a very-low-leakage state (see the

Electrical Characteristics table). This mode is conve-

nient for making IDDQ and PMU measurements without

the need for an output disconnect relay. LLEAK control

is independent for each channel.

When DUT_ is driven with a high-speed signal while

LLEAK is asserted, the leakage current momentarily

increases beyond the limits specified for normal opera-

tion. The low-leakage recovery specification in the

Electrical Characteristics table indicates device behav-

ior under this condition.

Temperature Monitor

Each device supplies a single temperature output sig-

nal, TEMP, that asserts a nominal 3.43V output voltage

at a +70°C (343K) die temperature. The output voltage

increases proportionately with temperature at a rate of

10mV/°C. The temperature sensor output impedance is

500Ω, typical.

Table 2. Comparator Logic

DUT_ > CHV_

DUT_ > CLV_

CMPH_

CMPL_

00

0

0

01

0

1

10

1

0

11

1

1

Table 3. Passive Load Resistance Values

HIGH RESISTOR (k

Ω)

LOW RESISTOR (k

Ω)

7.5

2

MAX9972

COMPHI

CHV_

DUT_

CLV_

COMPLO

50

Ω

CMPH_

50

Ω

CMPL_

Figure 3. Complementary 50Ω Comparator Outputs