LM393DT_15 Datasheet, PDF (26/38 Pages) Rohm – SIGNATURE SERIES Comparators

LM393xxx LM2903xx LM339xx LM2901xx
Datasheet
Operational Notes – continued
11. Regarding Input Pins of the IC
This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them
isolated. P-N junctions are formed at the intersection of the P layers with the N layers of other elements, creating a
parasitic diode or transistor. For example (refer to figure below):
When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.
When GND > Pin B, the P-N junction operates as a parasitic transistor.
Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual
interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to
operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should be
avoided.
Resistor
Transistor (NPN)
Pin A
N ^P+ N
Parasitic
Element
P _N P⁺ _N
P Substrate
GND
Pin A
Pin B _C
B
E
Pin B
Parasitic
Element
N ^P+
N _{P N P}⁺ _N
P Substrate
BC
E
Parasitic
Element
Parasitic
Element
GND
GND
GND
Parasitic element
or Transistor
Figure 52. Example of Monolithic IC Structure
12. Unused Circuits
When there are unused circuits it is recommended that they be connected as in Figure 53, setting the non-inverting
input pin to a potential within the in-phase input voltage range (V_ICM).
Please keep
this potential in V_ICM
V_ICM
Vcc⁺
+
OPEN
-
Vcc^-
Figure 53. Disable Circuit Example
13. Input Voltage
Applying Vcc^- + 36V to the input pin is possible without causing deterioration of the electrical characteristics or
destruction, regardless of the supply voltage. However, this does not ensure normal circuit operation. Please note that
the circuit operates normally only when the input voltage is within the common-mode input voltage range of the electric
characteristics.
14. Power Supply (single/dual)
The comparator operates when the specified voltage supplied is between Vcc⁺ and Vcc^-. Therefore, the single supply
comparator can be used as a dual supply comparator as well.
15. Terminal short-circuits
When the output and Vcc⁺ pins are shorted, excessive output current may flow, resulting in undue heat generation and,
subsequently, destruction.
16. IC Handling
Applying mechanical stress to the IC by deflecting or bending the board may cause fluctuations in the electrical
characteristics due to piezo resistance effects.
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