15

LTC1642A

1642af

Uncommitted Comparator

The uncommitted comparator has an open drain output.

The comparator has 3mV of hysteresis: the output goes

high when the differential input voltage exceeds 1.5mV

and goes low when the differential input is less than

–1.5mV.

The comparator’s input transistors are MOSFETs so the

input bias and offset currents are very small: typically

picoamps at 25

°C, increasing to nanoamps at 90°C. If the

COMPOUT pins may be left floating.

APPLICATIO S I FOR ATIO

R6

SENSE

RESISTOR, R2

TO SHORT

R2

1642a F15

R5

LT1642A

Figure 15. Recommended Layout for R1, R2 and R5

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

Layout Considerations

One ounce copper exhibits a sheet resistance of 530

µΩ

per square. To minimize self-heating, traces should be

at least 0.02" wide per ampere of current and 0.03" is

recommended.

In high current applications, the voltage drop along traces

SENSE pins

directly across sense resistor R2 to prevent

the power trace’s resistance from adding to R2. It is also

a good practice to keep the resistor divider to the ON pin

and GND pins short. Figure 15 shows an example layout.