Datasheet

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SBOS301A − MAY 2004 − REVISED MARCH 2007
www.ti.com
5
ELECTRICAL CHARACTERISTICS: V
S
= +5V
Boldface limits apply over the specified temperature range, T
A
= −5°C to +75°C.
All specifications at T
A
= +25°C, R
VLOGOUT
= 10kΩ, V
CM
= +2.5V, unless otherwise noted.
LOG114
PARAMETER CONDITIONS MIN TYP MAX UNITS
CORE LOG FUNCTION I
IN
/V
OUT
Equation V
O
= (0.375V) Log (I
1
/I
2
) + V
CM
V
LOG CONFORMITY ERROR
(1)
Initial 1nA to 100µA (5 decades) 0.1 0.25 %
0.009 0.022 dB
100pA to 3.5mA (7.5 decades) 0.9 %
0.08 dB
1mA to 10mA See Typical Characteristics
Over Temperature 1nA to 100µA (5 decades) 0.1 0.4 %
100pA to 3.5mA (7.5 decades) 0.5 %
1mA to 10mA See Typical Characteristics
TRANSFER FUNCTION (GAIN)
(2)
Initial Scaling Factor 10nA to 100µA 0.375 V/decade
Scaling Factor Error 1nA to 100µA 0.4 ±2.5 %
0.0.35 0.21 dB
Over Temperature T
MIN
to T
MAX
0.035 ±3.5 %
+15°C to +50°C 0.7 ±3 %
INPUT, A
1
and A
2
Offset Voltage V
OS
±1 ±7 mV
vs Temperature dV/dT T
MIN
to T
MAX
+30 µV/°C
vs Power Supply PSRR V
S
= +4.5V to +5.5V 300 µV/V
Input Bias Current I
B
±5 pA
vs Temperature T
MIN
to T
MAX
Doubles every 10°C
Input Common-Mode Voltage Range V
CM
(V−)+1.5 to
(V+)−1.5
V
Voltage Noise e
n
f = 0.1Hz to 10kHz 3 µVrms
f = 1kHz 30 nV/√Hz
Current Noise i
n
f = 1kHz 4 fA/√Hz
OUTPUT, A
3
(V
LOGOUT
)
Output Offset, V
OSO
, Initial V
OSO
±14 ±65 mV
Over Temperature T
MIN
to T
MAX
±18 ±80 mV
Full Scale Output (FSO)
(3)
V
S
= +5V (V−) + 0.6 (V+) − 0.6 V
Gain Bandwidth Product GBW I
IN
= 1µA 50 MHz
Short-Circuit Current I
SC
±18 mA
Capacitive Load 100 pF
OP AMP, A
4
and A
5
Input Offset Voltage V
OS
±250 ±4000 µV
vs Temperature dV/dT T
MIN
to T
MAX
±2 µV/°C
vs Supply PSRR V
S
= +4.8V to +5.5V 30 µV/V
vs Common-Mode Voltage CMRR 70 dB
Input Bias Current I
B
−1 µA
Input Offset Current I
OS
±0.05 µA
Input Voltage Range (V−) (V+) − 1.5 V
Input Noise f = 0.1Hz to 10Hz 1 µV
PP
f = 1kHz 28 nV/√Hz
Current Noise i
n
2 pA/√Hz
Open-Loop Voltage Gain A
OL
100 dB
Gain Bandwidth Product GBW 15 MHz
Slew Rate SR 5 V/µs
Settling Time 0.01% t
S
G = −1, 3V Step, C
L
= 100pF 1.5 µs
Rated Output (V−) + 0.5 (V+) − 0.5 V
Short-Circuit Current I
SC
+4/−10 mA