LM339LVDR datasheet(21/63 Pages) TI1

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7.4.3.3 Input Protection

The input bias current is typically 5 pA for input voltages between V+ and GND. The comparator inputs are

protected from reverse voltage by the internal ESD diodes connected to GND. As the input voltage goes under

GND, or above the input Absolute Maximum ratings the protection diodes become forward biased and begin to

conduct causing the input bias current to increase exponentially. Input bias current typically doubles for each

10°C temperature increase.

If the inputs are to be connected to a low impedance source, such as a power supply or buffered reference line,

TI recommends adding a current-limiting resistor in series with the input to limit any transient currents should the

clamps conduct. The current should be limited 10 mA or less. This series resistance can be part of any resistive

input dividers or networks.

7.4.4 ESD Protection

The LV family incorporates internal ESD protection circuits on all pins. The inputs, and the open-drain output,

use a proprietary "snapback" type ESD clamp from each pin to GND, which allows the pins to exceed the supply

voltage (V+). While shown as Zener diodes, snapbacks momentarily "short" and go low impedance (like an

SCR) when the threshold is exceeded, as opposed to clamping to a defined voltage like a Zener. There is no

ESD clamp from the inputs to V+.

The open-drain output protection also consists of a ESD clamp between the output and GND to allow the output

to be pulled above V+ to a maximum of 5.5V. There is no ESD clamp from the output to V+.

If the inputs are to be connected to a low impedance source, such as a power supply or buffered reference line,

TI recommends adding a current-limiting resistor in series with the input to limit any transient currents should the

clamps conduct. The current should be limited 10 mA or less. This series resistance can be part of any resistive

input dividers or networks.

TI does not specify the performance of the ESD clamps and external clamping diodes should be added if the

inputs or output could exceed the maximum ratings as part of normal operation.

7.4.5 Unused Inputs

If a channel is not to be used, DO NOT tie the inputs together. Due to the high equivalent bandwidth and low

offset voltage, tying the inputs directly together can cause high frequency oscillations as the device triggers on

it's own internal wideband noise. Instead, the inputs should be tied to any available voltage that resides within

the specified input voltage range and provides a minimum of 50mV differential voltage. For example, one input

can be grounded and the other input connected to a reference voltage, or even V+ (as long as the input is

directly connected to the V+ pin to avoid transients).

7.4.6 Hysteresis

The LV family does not have internal hysteresis. Due to the wide effective bandwidth and low input offset

voltage, it is possible for the output to "chatter" (oscillate) when the absolute differential voltage near zero, as the

comparator triggers on it's own internal wideband noise. TI recommends that the user add external hysteresis if

slow moving signals are expected. See Section 8.1.2 in the following section.

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TL331LV, TL391LV, LM393LV, LM339LV

SNOSDA4C – JUNE 2020 – REVISED MARCH 2023

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LM339LVDR Datasheet(PDF) 21 Page - Texas Instruments