FOD2712 Datasheet, PDF (3/13 Pages) Fairchild Semiconductor – OPTICALLY ISOLATED ERROR AMPLIFIER

OPTICALLY ISOLATED
ERROR AMPLIFIER
FOD2712
ELECTRICAL CHARACTERISTICS (V_CC = 12V, T_A = 25°C Unless otherwise specified.)
INPUT CHARACTERISTICS
Parameter
Test Conditions Symbol Min Typ** Max Unit
LED forward voltage
(I_LED = 10 mA, V_COMP = V_FB)(Fig.1)
V_F
1.5 V
Reference voltage
(-40 to +85°C)
(25°C)
(V_COMP = V_FB, I_LED = 10 mA (Fig.1)
V_REF
1.221
1.259
V
1.228 1.240 1.252
Deviation of V_REF over temperature - See Note 1
(T_A = -40 to +85°C) V_{REF (DEV)}
4
12 mV
Ratio of Vref variation
to the output of the error amplifier
(I_LED = 10 mA, ∆V_REF/
V_COMP = V_REF to 12 V) (Fig.2) ∆V_COMP
-1.5 -2.7 mV/V
Feedback input current
(I_LED = 10 mA, R1 = 10 kΩ) (Fig.3)
I_REF
0.15 0.5 µA
Deviation of I_REF over temperature - See Note 1
(T_A = -40 to +85°C) I_{REF (DEV)}
0.15 0.3 µA
Minimum drive current
(V_COMP = V_FB) (Fig.1) I_{LED (MIN)}
55 80 µA
Off-state error amplifier current
(V_LED = 6 V, V_FB = 0) (Fig.4) I_(OFF)
0.001 0.1 µA
Error amplifier
output impedance - See Note 2
(V_COMP = V_FB, I_LED = 0.1 mA to 15 mA,
f<1 kHZ)
|Z_OUT|
0.25
Ohm
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--T--A--^A-----=------2---5----°--C-----⁾--^}-----^×----1----0---⁶-
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 + ^RR-----12--
© 2003 Fairchild Semiconductor Corporation
Page 3 of 13
4/10/03