MAX9949 데이터 시트보기 (PDF) - Maxim Integrated

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MAX9949

Dual Per-Pin Parametric Measurement Units

Maxim Integrated 

Dual Per-Pin Parametric Measurement Units

VDUT

VEE - 3.5V

VEE - 5V

IDUT

IMIN

IMIN

Figure 8. PMU Force Output Capability

VEE + 5V

VEE + 3.5V

Short-Circuit Protection

The FORCE_ output and SENSE_ input can withstand a

short to any voltage between the supply rails.

Mode and Range Change Transients

The MAX9949/MAX9950 feature make-before-break

switching to minimize glitches. The integrated voltage

clamps also reduce glitching on the output.

DUT Voltage Swing vs. DUT Current and

Power-Supply Voltages

Several factors limit the actual DUT voltage that the

PMU delivers:

1) The overhead required by the amplifiers and other

integrated circuitry—this is typically 3.5V from each

rail for no load current and 5V under full load

2) The voltage drop across the current-range select

resistor and internal circuitry in series with the sense

resistor—at full current, the combined voltage drop is

typically 2.75V

3) Variations in the power supplies—system implemen-

tation determines the variance

4) Variation of DUT ground vs. PMU ground—system

implementation determines the variance

Neglecting the effects of the third and fourth items,

Figure 8 demonstrates the force output capabilities

of the PMU.

Figure 8 indicates that, for zero DUT current, the

DUT voltage swings from (VEE + 3.5V) to (VCC -

3.5V). For larger positive DUT currents, the positive

swing drops off linearly until it reaches (VCC - 5V) at

full current. Similarly, for larger negative DUT cur-

rents, the negative voltage swing drops off linearly

until it reaches (VEE + 5V) at full current.

Settling Times and Compensation

Capacitors

The data in the Electrical Characteristics table reflects

the circuit shown in the block diagram that includes a

single compensation capacitor (Cx) effectively across all

the sense resistors. Placing individual capacitors, CRA,

CRB, CRC, CRD, and CRE directly across the sense

resistors, R_A, R_B, R_C, R_D, and R_E, independently

optimizes each range.

The combination of the capacitance across the sense

resistors (Cx or CRA, CRB, CRC, CRD, and CRE) and the

main amplifier compensation comparator, CCM, ensures

stability into the maximum expected load capacitance

while optimizing settling time.

Digital Inputs (SCLK, DIN, CS, LOAD)

The digital inputs incorporate hysteresis to mitigate

issues with noise, as well as provide for compatibility

with opto-isolators that can have slow edges.

PROCESS: BiCMOS

Chip Information

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