FOD2742BR2 Datasheet, PDF (4/16 Pages) Fairchild Semiconductor – Optically Isolated Error Amplifier

Electrical Characteristics (T_A = 25°C unless otherwise specified)
Input Characteristics
Symbol
Parameter
Test Conditions
Device Min. Typ. Max. Unit
V_F
V _REF
LED Forward Voltage
Reference Voltage
I_LED = 10mA, V_COMP = V_FB (Fig. 1)
I_LED = 10mA, V_COMP = V_FB (Fig. 1)
All
1.20 1.5 V
A 2.482 2.495 2.508 V
B 2.470 2.495 2.520 V
C 2.450 2.500 2.550 V
V_{REF (DEV)} Deviation of V_REF Over
Temperature
T_A = -25°C to +85°C (Fig. 1)
All
3.5 17 mV
∆V_RE Ratio of V_REF Variation to I_LED = 10mA ∆V_COMP = 10V to V_REF
All
∆V_COMP the Output of the Error
Amplifier
(Fig. 2)
∆V_COMP = 36V to 10V
-0.5 -2.7 mV/
-0.3 -2.0 ^V
I_REF Feedback Input Current
I_LED = 10mA, R₁ = 10KΩ (Fig. 3)
All
I_{REF (DEV)} Deviation of I_REF Over
T_A = -25°C to +85°C (Fig. 3)
All
Temperature
2.2
4 µA
1.0 1.2 µA
I_{LED (MIN)} Minimum Drive Current
V_COMP = V_FB (Fig. 1)
All
I_(OFF) Off-state Error Amplifier
V_LED = 37V, V_FB = 0 (Fig. 4)
All
Current
|Z_OUT| Error Amplifier Output
V_COMP = V_REF, I_LED = 1mA to 20mA,
All
Impedance (see note 2) f ≥ 1.0kHz
0.45 1.0 mA
0.01 1.0 µA
0.15 0.5 Ω
Notes:
1. The deviation parameters V_REF(DEV) and I_REF(DEV) are defined as the differences between the maximum and
minimum values obtained over the rated temperature range. The average full-range temperature coefficient of the
reference input voltage, ∆V_REF, is defined as:
∆V_REF (ppm/°C)
=
{_{----V----R----E---F---(--D----E----V---)--/--V----R----E---F----}(_{--T----A-----=------2---5----°--C-----})_--}_-----×_{----1----0---}⁶_-
∆T_A
where ∆T_A is the rated operating free-air temperature range of the device.
2. The dynamic impedance is defined as |Z_OUT| = ∆V_COMP/∆I_LED. When the device is operating with two external
resistors (see Figure 2), the total dynamic impedance of the circuit is given by:
Z_{OUT, TOT} = ^∆--_∆---V-I- ≈ Z_OUT ×
1 + ^R-----1--
R2
©2003 Fairchild Semiconductor Corporation
FOD2742A, FOD2742B, FOD2742C Rev. 1.0.1
4
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