Datasheet NJU7890 (New Japan Radio) - 6

NJU7890 PRELIMINARY SPECIFICATIONS SUBJECT TO CHANGE ■ +HVIN input Voltage Range
In order for this IC to operate normally, the positive input terminal voltage −HVIN (V+IN) of operational amplifier A must be within the common mode input voltage range of operational amplifier A. R1 Operational amplifier A: common mode input voltage range R2 V+ V- ≤ V −IN B +IN ≤ V+ -0.85V A Therefore, it is necessary to satisfy the following formula expressed by +IN V+/V− (supply voltage), V R2 +HVIN (+HVIN terminal voltage), VREF (REF R1 V− terminal voltage), ATT (attenuation rate). REF +HVIN Calculation ATT = R2/R1 1 1 V- ≤ × V+HVIN + × VREF ≤ V+ -0.85V 1 + ATT-1 1 + ATT Calculation example VREF = 4V, V+ / V− = 5V / 0V, ATT = 1/205 1 1 0V ≤ × V × 4V ≤ 5V -0.85V 1 + 205 +HVIN + 1 + 1⁄205 -820V ≤ V+HVIN ≤ 34.9V Characteristics example The figure below shows an example of characteristics when the attenuation rate is set to 1/205 (Aver) and 1/311 (Bver). The range indicated by the graph is the input voltage range of the +HVIN.
+HVIN Input Voltage Range vs REF Voltage V+/V- = 5V/0V, VREF = 0 to 4.15V 1400 ] 1200
ATT = 1/205 (Aver.)
[V 1000
ATT = 1/311 (Bver.)
e g 800 n a 600 e R 400 g lta 200 o 0 t V -200 -400 Inpu IN -600 V H -800 + -1000 -1200 -1400 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 REF Voltage [V]
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