MAX4206ETE+T Maxim Integrated Products, MAX4206ETE+T Datasheet - Page 13

• Manufacturer Part Number: MAX4206ETE+T
• Description: IC AMP TRANS LOG 16-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX4206ETE+T

• Amplifier Type: Logarithmic
• Number Of Circuits: 1
• Slew Rate: 12 V/µs
• Gain Bandwidth Product: 5MHz
• Voltage - Input Offset: 1000µV
• Current - Supply: 5mA
• Current - Output / Channel: 58mA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 11 V, ±2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TQFN Exposed Pad
• Number Of Channels: 1
• Input Offset Voltage: 5 mV
• Operating Supply Voltage: 3 V, 5 V, 9 V
• Supply Current: 5 mA
• Operating Temperature Range: + 85 C
• Mounting Style: SMD/SMT
• Power Dissipation: 1349 mW
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• -3db Bandwidth: -
• Current - Input Bias: -
• Lead Free Status / Rohs Status: Details

The MAX4206 bandwidth is proportional to the magni-
tude of the I
inversely proportional to I
A common-mode input voltage, V
available at CMVOUT and can be used to bias the log-
ging and reference amplifier inputs by connecting
CMVOUT to CMVIN. An external voltage between 0.5V
and 1V can be applied to CMVIN to bias the logging
and reference transistor collectors and to optimize the
performance required for both single- and dual-supply
operation.
Adjust the logarithmic intercept by changing the refer-
ence current, I
(see Figures 5 and 6) adjusts the reference current,
according to the following equation:
where V
5MΩ. REFIOUT current range is 10nA to 10µA only.
When operating from a single +2.7V to +11V supply,
I
slope of the log output voltages, LOGV1 and LOGV2.
Bias the log and reference amplifiers by connecting
CMVOUT to CMVIN or connecting an external voltage
reference between 0.5V and 1V to CMVIN. For single-
supply operation, connect V
Select R
(see Figure 5). The magnitude of the offset voltage is
given by:
The scale factor, K, is the slope of the logarithmic out-
put. For the LOGV1 amplifier, K = 0.25V/decade. When
operating in a single-supply configuration, adjust the
overall scale factor for the MAX4206 using the uncom-
mitted LOGV2 amplifier and the following equation,
which refers to Figure 5:
LOG
Amplifier with Over 5 Decades of Dynamic Range
Frequency Response and Noise Considerations
must be greater than I
REFISET
OS
Adjusting the Logarithmic Intercept
REF
and I
REF
and I
is 0.5V. Select R
OS
V
R
______________________________________________________________________________________
R
OS
. A resistor from REFISET to GND
SET
2
LOG
to adjust the output offset voltage
=
= R
R
=
Precision Transimpedance Logarithmic
1
Single-Supply Operation
REF
V
10



currents, whereas the noise is
OS
REFISET
0 25
EE
.
×
K
REF
and I
I
REF
to GND.
I
OSADJ
−
, resulting in a positive
SET
1
LOG



CMVOUT
Common Mode
between 5kΩ and
currents.
Output Offset
Scale Factor
, of 0.5V is
Select R1 between 1kΩ and 100kΩ, with an ideal value
of 10kΩ. The noninverting amplifier ensures that the
overall scale factor is greater than or equal to
0.25V/decade for single-supply operation.
Desired:
Because there is no offset current applied to the circuit
(R
intercept of 100µA. Therefore,
Select R
When operating from dual ±2.7 to ±5.5V supplies, it is
not required that I
output voltage results at LOGV1 when I
I
I
amplifiers by connecting CMVOUT to CMVIN or con-
nect an external 0.5V to 1V reference to CMVIN. For
dual-supply operation with CMVIN < 0.5V, refer to the
MAX4207 data sheet.
The uncommitted amplifier in the inverting configuration
utilized by the MAX4206 facilitates large output-offset
voltage adjustments when operated with dual supplies.
The magnitude of the offset voltage is given by the fol-
lowing equation:
A resistive divider between REFVOUT, OSADJ, and
GND can be used to adjust V
REF
LOG
OS
Single-Supply Operation
Logarithmic intercept: 100nA
Overall scale factor = 1V/decade
. A negative output voltage results at LOGV1 when
= 0Ω), the reference current, I
is less than I
1
= 10kΩ:
R
V
R
OSADJ
SET
2 10
V
=
OS
LOG
=
REF
k
10 100
=
Ω
=
V
be greater than I
V



. Bias the log and reference
×
OSADJ
0 5
REFOUT
1
0 25
.
V V
Dual-Supply Operation
.
V
/
OSADJ
nA
−



1
1
=




 =

+
R
500
R
R
3
2
REF
30
1
(see Figure 6).
R
+



4
Design Example
k
k
R
Ω
, equals the log
Ω
4
REF
Output Offset
LOG



. A positive
exceeds
13