Datasheet

LOG112, 2112
4
SBOS246D
www.ti.com
FREQUENCY RESPONSE, CORE LOG
(5)
BW, 3dB
I
2
= 10nA C
C
= 4500pF 0.1 kH
I
2
= 1µAC
C
= 150pF 38 kH
I
2
= 10µAC
C
= 150pF 40 kH
I
2
= 1mA C
C
= 50pF 45 kHz
Step Response
Increasing
I
1
= 10nA to 100nA C
C
= 120pF, I
2
= 31.6nA 1.1 ms
I
1
= 1µA to 100µAC
C
= 375pF, I
2
= 10µA 1.6 µs
I
1
= 1µA to 1mA C
C
= 950pF, I
2
= 31.6µA 1.5 µs
Decreasing
I
1
= 100nA to 10nA C
C
= 120pF, I
2
= 31.6nA 2.1 ms
I
1
= 100µA to 1µAC
C
= 375pF, I
2
= 10µA 31.2 µs
I
1
= 1mA to 1µAC
C
= 950pF, I
2
= 31.6µA39µs
Increasing
I
2
= 10nA to 100nA C
C
= 125pF, I
1
= 31.6nA 2.6 ms
I
2
= 1µA to 100µAC
C
= 750pF, I
1
= 10µA 113 µs
I
2
= 1µA to 1mA C
C
= 10.5nF, I
1
= 31.6µA 1.2 ms
Decreasing
I
2
= 100nA to 10nA C
C
= 125pF, I
1
= 31.6nA 630 µs
I
2
= 100µA to 1µAC
C
= 750pF, I
1
= 10µA 6.6 µs
I
2
= 1mA to 1µAC
C
= 10.5nF, I
1
= 31.6µA 13.3 µs
OP AMP, A3
Input Offset Voltage +250 ±1000 µV
vs Temperature T
MIN
to T
MAX
±2 µV/°C
vs Supply V
S
= ±4.5V to ±18V 5 50 µV/V
Input Bias Current –10 nA
Input Offset Current ±0.5 nA
Input Voltage Range (V–) (V+) – 1.5 V
Input Noise, f = 0.1Hz to 10Hz 1 µV
PP
f = 1kHz 28 nV/
√Hz
Open-Loop Voltage Gain 88 dB
Gain-Bandwidth Product 1.4 MHz
Slew Rate 0.5 V/µs
Settling Time, 0.01% G = –1, 3V Step, C
L
= 100pF 16 µs
Rated Output (V–) + 1.5 (V+) – 0.9 V
Short-Circuit Current ±4mA
VOLTAGE REFERENCE
Bandgap Voltage 2.5 V
Error, Initial ±0.05 ±0.5 %
vs Temperature T
MIN
to T
MAX
±25 ppm/°C
vs Supply V
S
= ±4.5V to ±18V ±10 ppm/V
vs Load I
LOAD
= 10mA ±600 ppm/mA
Short-Circuit Current 16 mA
POWER SUPPLY
Operating Range V
S
±4.5 ±18 V
Quiescent Current I
O
= 0
LOG112 ±1.25 ±1.75 mA
LOG2112 ±2.5 ±3.5 mA
TEMPERATURE RANGE
Specified Range, T
MIN
to T
MAX
–575°C
Operating Range –40 85 °C
Storage Range –55 125 °C
Thermal Resistance,
θ
JA
SO-14 110 °C/W
SO-16 80 °C/W
NOTES: (1) Log Conformity Error is the peak deviation from the best-fit-straight line of V
O
vs LOG(I
1
/I
2
) curve expressed as a percent of peak-to-peak full-scale
output. K, scale factor, equals 0.5V output per decade of input current. (2) Scale factor of core log function is trimmed to 0.5V output per decade change of input
current. (3) Worst-case Total Error for any ratio of I
1
/I
2
, as the largest of the two errors, when I
1
and I
2
are considered separately. (4) Total Error includes offset
voltage, bias current, gain, and log conformity. (5) Bandwidth (3dB) and transient response are a function of both the compensation capacitor and the level of input
current.
ELECTRICAL CHARACTERISTICS (Cont.)
Boldface limits apply over the specified temperature range, T
A
= –5°C to +75°C.
At T
A
= +25°C, V
S
= ±5V, and R
L
= 10kΩ, unless otherwise noted.
LOG112, LOG2112
PARAMETER CONDITION MIN TYP MAX UNITS