General Description
The MAX4004/MAX4006 precision, high-side, current
monitors are specifically designed for monitoring photo-
diode current in fiber applications. They offer a connec-
tion point for the reference current and a monitor output
that produces a signal proportional to the reference
current. The monitor output of the MAX4004 is a current
proportional to the reference current. The monitor out-
put of the MAX4006 is a voltage proportional to the ref-
erence current. The current monitors have six decades
of dynamic range and monitor reference current of
250nA to 2.5mA with better than 5% accuracy. The
photodiode current can be monitored from 10nA to
10mA with reduced accuracy.
The MAX4004/MAX4006 accept a +2.7V to +22V supply
voltage, suitable for PIN photodiode applications. (For
higher voltage applications, refer to the MAX4007/
MAX4008 data sheet.) Internal current limiting (20mA,
typ) protects the device against short-circuit-to-ground or
excessive current conditions. A clamp diode protects the
monitor output from overvoltage. Additionally, these
devices feature thermal shutdown if the die temperature
reaches +150°C.
The MAX4004/MAX4006 are available in tiny, space-
saving 6-pin SOT23 packages, and operate over the
extended temperature range of -40°C to +85°C.
Applications
Photodiode Current-Monitoring Systems
Portable Instrumentation
Medical Instrumentation
Laboratory Instrumentation
Consumer Electronics
Current-to-Voltage Conversion
Level Translation
Features
♦Wide Reference Current Dynamic Range
Guaranteed 250nA to 2.5mA with 5%
Accuracy
Extended 10nA to 10mA with 10% Monitor
Accuracy
♦Current (MAX4004) or Voltage (MAX4006) Monitor
Output
♦Reference Current-Limit Protection (20mA, typ)
♦Voltage Clamp Protects Subsequent Output
Circuitry
♦+2.7V to +22V Wide Voltage Range Operation
♦6-Pin SOT23 Packages
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
________________________________________________________________ Maxim Integrated Products 1
GND
REFOUT
16BIAS
5N.C.
CLAMP
MAX4004
MAX4006
SOT23
TOP VIEW
2
34
Pin Configuration
Ordering Information
19-2742; Rev 2; 2/06
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Typical Operating Circuit appears at end of data sheet.
PART
PIN-PACKAGE
TOP MARK
PKG
CODE
MAX4004EUT-T
6 SOT23-6 ABNL U6S-3
MAX4006EUT-T
6 SOT23-6 ABNN U6S-3
Selector Guide
PART
PIN-PACKAGE
INTERNAL
RESISTOR
TYPICAL
ACCURACY
MAX4004EUT-T
6 SOT23-6 None 5%
MAX4006EUT-T
6 SOT23-6 10kΩ1%
Note: All devices are specified over the -40°C to +85°C operating
temperature range.
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
CLAMP to GND ......................................................-0.3V to +25V
BIAS, REF to GND ..................................................-0.3V to +25V
OUT to GND .........................................-0.3V to (VCLAMP + 0.6V)
Short-Circuit, REF to GND..........................................Continuous
Current into any Pin ..........................................................±30mA
Continuous Power Dissipation (TA= +70°C)
6-Pin SOT23 (derate 8.7mW/°C above +70°C)............696mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(VBIAS = 5V, GND = 0V, REF = Open, VOUT = 0V (MAX4004), CLAMP = Open, TA= -40°C to +85°C. Typical values are at TA= +25°C,
unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS MIN TYP MAX
UNITS
Bias Voltage Range VBIAS Inferred from power-supply
rejection test 2.7 22 V
IREF = 250nA 40 100 µA
Bias Quiescent Current IBIAS IREF = 2.5mA 3.6 4 mA
Reference Voltage VREF IREF = 2.5mA
VBIAS - 1.1 VBIAS - 0.8
V
Thermal Shutdown
Engage Temperature TSHDN REF shorted to GND, junction
temperature rising 150 °C
Trip-Point Temperature
Hysteresis THYS REF shorted to GND, junction
temperature falling 5°C
Input Current Limit ILIM VREF = VBIAS - 5V 20 mA
IREF = 250nA
0.3
f = 0.1Hz to 10Hz
IREF = 2.5mA
63
IREF = 250nA
9.2
MAX4004
Output Current Noise iNOUT
f = 0.1Hz to 10kHz IREF = 2.5mA
1240
pARMS
IREF = 250nA
0.041
f = 0.1Hz to 10Hz
IREF = 2.5mA
0.63
IREF = 250nA
1.3
MAX4006
Output Voltage Noise eNOUT
f = 0.1Hz to 10kHz IREF = 2.5mA
12.5
µVRMS
IREF = 250nA
50 GΩ
MAX4004
IREF = 2.5mA
5MΩ
Output Resistance ROUT
MAX4006 10 kΩ
Output Leakage REF = open 1 pA
Output Voltage Range VOUT
V
BIA S
= 2.7V to 22V , IRE F
= 0 to 1m A,
MAX4004: ∆IOUT/IOUT = ±1%,
MAX4006: ∆VOUT/IOUT = ±1%
0 to VBIAS
- 1.5
0 to VBIAS
- 0.85 V
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
_______________________________________________________________________________________ 3
Note 1: All devices are 100% tested at room temperature (TA= +25°C). All temperature limits are guaranteed by design.
ELECTRICAL CHARACTERISTICS (continued)
(VBIAS = 5V, GND = 0V, REF = Open, VOUT = 0V (MAX4004), CLAMP = Open, TA= -40°C to +85°C. Typical values are at TA= +25°C,
unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS MIN TYP MAX
UNITS
Output Clamp Voltage VOUT -
VCLAMP 0.6 V
Output Clamp Leakage VCLAMP = 0 to 22V 1 pA
IREF = 250nA 0.09 0.099 0.11
IREF = 2.5mA 0.094 0.095 0.106MAX4004 Current Gain IOUT/IREF
IREF = 10mA, VBIAS = 12V 0.098
mA/mA
IREF = 250nA 0.9 0.995 1.1
IREF = 2.5mA 0.95 0.998 1.05
MAX4006
Transimpedance Gain
VOUT/IREF
IREF = 10mA, VBIAS = 12V 0.992
V/mA
IREF = 250nA
50 1000
(∆IOU T
/IOU T
)
/∆VBIAS
MAX4004:
VBIAS = 2.7V to 22V IREF = 1mA
50 1000
Power-Supply Rejection
Ratio (PSRR)
( ∆V
OU T
/V
OU T
)
/∆VBIAS
MAX4006:
VBIAS = 2.7V to 22V IREF = 1mA
50 1000
ppm/V
IREF = 250nA
7.5 ms
Power-Up Settling Time tS
IOU T settl es w ithi n 0.1%,
C
IN
= 10nF b etw een
RE F and GN D
IREF = 2.5mA
90 µs
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
4_______________________________________________________________________________________
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
BIAS CURRENT
vs. SUPPLY VOLTAGE
MAX4004/6 toc01
SUPPLY VOLTAGE (V)
BIAS CURRENT (mA)
20148
0.1
1
10
0.01
226
IREF = 250nA
IREF = 2.5mA
BIAS CURRENT
vs. REFERENCE CURRENT
MAX4004/6 toc02
IREF (A)
BIAS CURRENT (mA)
1m100µ
10µ
1µ
100n
0.1
1
10
0.01
10n 10m
VBIAS = 5V
BIAS CURRENT
vs. TEMPERATURE
MAX4004/6 toc03
TEMPERATURE (°C)
BIAS CURRENT (mA)
603510-15
0.1
1
10
0.01
-40 85
IREF = 250nA
IREF = 2.5mA VBIAS = 5V
GAIN ERROR
vs. REFERENCE CURRENT
MAX4004/6 toc04
IREF (A)
GAIN ERROR (%)
1m100µ
10µ
1µ
100n
-4
-3
-2
-1
0
1
2
3
4
5
-5
10n 10m
VBIAS = 5V
-4.0
-2.5
-3.0
-3.5
-2.0
-1.5
-1.0
-0.5
0
0.5
1.0
-40 10-15 35 60 85
GAIN ERROR vs. TEMPERATURE
MAX4004/6 toc05
TEMPERATURE (°C)
GAIN ERROR (%)
IREF = 10nA
IREF = 5mA
IREF = 2.5A
IREF = 250µA
IREF = 2.5µA
IREF = 250nA
VBIAS = 5V
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0
0.2
271217 22
GAIN ERROR
vs. BIAS VOLTAGE
MAX4004/6 toc06
VBIAS (V)
GAIN ERROR (%)
IREF = 250nA
IREF = 25µA
IREF = 2.5mA
IREF = 5mA
TRANSIENT RESPONSE
(VBIAS = 5V)
MAX4004/6 toc07
IOUT
0.1mA/div
IREF
1.0mA/div
400ns/div
0A
0A
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
_______________________________________________________________________________________ 5
10ms/div
STARTUP DELAY
(VBIAS = 2.7V, IREF = 250nA)
CH1
MAX4004/6 toc10
0V
0V
CH2
RREF = 8.8MΩ
R1 = 0Ω
RTEST = 8.1MΩ
CH1: 1V/div
CH2: 50mV/div
VBIAS
RTEST
RREF
BIAS
CH2
13pF
CH1
R1
D.U.T.
REF OUT
10ms/div
STARTUP DELAY
(VBIAS = 2.7V, IREF = 2.5mA)
CH1
MAX4004/6 toc11
0V
0V
CH2
RREF = 794Ω
R1 = 0Ω
RTEST = 4.01kΩ
CH1: 1V/div
CH2: 200mV/div
VBIAS
RTEST
RREF
BIAS
CH2
13pF
CH1
R1
D.U.T.
REF OUT
20ms/div
SHORT-CIRCUIT RESPONSE
(VBIAS = 5V)
MAX4004/6 toc12
0A
CH1
CH1: IBIAS, 10mA/div
A: REF SHORTS TO GND
B: CURRENT LIMIT ACTIVE
C: THERMAL SHUTDOWN
AB
C
TA = +148°C
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
40ms/div
STARTUP DELAY
(VBIAS = 5V, IREF = 250nA)
CH1
MAX4004/6 toc08
0V
0V
CH2
RREF = 16.8MΩ
R1 = 118MΩ
RTEST = 1.67MΩ
CH1: 2V/div
CH2: 10mV/div
VBIAS
RTEST
RREF
BIAS
CH2
13pF
CH1
R1
D.U.T.
REF OUT
4ms/div
STARTUP DELAY
(VBIAS = 5V, IREF = 2.5mA)
CH1
MAX4004/6 toc09
0V
0V
CH2
RREF = 1.68kΩ
R1 = 0Ω
RTEST = 14.0kΩ
CH1: 2V/div
CH2: 1V/div
VBIAS
RTEST
RREF
BIAS
CH2
13pF
CH1
R1
D.U.T.
REF OUT
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
6_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
Pin Description
PIN
MAX4004 MAX4006 NAME FUNCTION
11CLAMP Clamp Voltage Input. External potential used for voltage
clamping of VOUT.
22GND Ground
3—OUT Current-Monitor Output. OUT sources a current of 1/10th IREF.
44REF Reference Current Output. REF provides the source current to
the cathode of the photodiode.
55N.C. No Connection. Not internally connected.
66BIAS Bias Voltage Input. Bias voltage for photodiode.
—3OUT
Current-Monitor Output. OUT presents a voltage proportional to
IREF at 1V/mA. An internal 10kΩ resistor connects OUT to GND
(see Functional Diagram).
10ms/div
SHORT-CIRCUIT RESPONSE
(VBIAS = 22V)
MAX4004/6 toc13
0A
CH1
CH1: IBIAS, 10mA/div
A: REF SHORTS TO GND
B: CURRENT LIMIT ACTIVE
C: THERMAL SHUTDOWN
ABC
TA = +120°C
VOLTAGE DROP
vs. REFERENCE CURRENT
MAX4004/6 toc14
REFERENCE CURRENT (A)
VBIAS - VREF (V)
1m100µ
10µ
1µ
0.20
0.40
0.60
0.80
1.00
1.20
1.40
0
100n 10m
A: TA = -40°C
B: TA = +25°C
C: TA = +85°C
D: TA = +100°C
A
B
C
D
VBIAS = 2.7V
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
_______________________________________________________________________________________ 7
Functional Diagrams
Detailed Description
The MAX4004/MAX4006 are versatile current monitors
intended for monitoring DC photodiode current in fiber
applications (see the Functional Diagram). The
MAX4004 output is a current that is exactly one-tenth of
the reference current. The MAX4006 outputs a voltage
that is proportional to the reference current with a tran-
simpedance gain of 1V/mA achieved by a factory-
trimmed, internal 10kΩresistor.
Both current devices have six decades of dynamic
range and monitor reference current ranging from 250nA
to 2.5mA, the nominal operating range, with better than
5% accuracy across the entire reference current, bias
voltage, and temperature ranges. The corresponding
monitor outputs produce 25nA to 0.25mA (MAX4004)
and 0.25mV to 2.5V (MAX4006). When the reference
currents are extended to the broader range of 10nA to
10mA, an accuracy of less than 10% is maintained.
Internal current limiting (20mA, typ) protects the device
against short-circuit-to-ground conditions, and a thermal
shutdown feature reduces both the reference current
and the monitor current to zero if the die temperature
reaches +150°C.
The MAX4004/MAX4006 accept a +2.7V to +22V
supply voltage, suitable for PIN photodiode applica-
tions. A clamping diode, shown in the Functional
Diagram, is provided to protect subsequent output cir-
cuitry from an overvoltage condition.
Applications Information
Clamping the Monitor Output Voltage
CLAMP provides a means for diode clamping the volt-
age at OUT, thus VOUT is limited to VCLAMP + 0.6V.
CLAMP can be connected to either an external supply,
to BIAS, or can be left floating if voltage clamping is not
required.
Using PIN Photodiodes in Fiber
Applications
When using the MAX4004/MAX4006 to monitor PIN
photodiode currents in fiber applications, several
issues must be addressed. In applications where the
photodiode must be fully depleted, keep track of volt-
ages budgeted for each component with respect to the
available supply voltage(s). The current monitor
requires as much as 1.2V between BIAS and REF,
which must be considered as part of the overall voltage
budget.
Additional voltage margin can be created if a negative
supply is used in place of a ground connection, as long
as the overall voltage drop experienced by the
MAX4004/MAX4006 is less than or equal to 22V. For
this type of application, the MAX4004 is suggested so
the output can be referenced to “true” ground and not
the negative supply. The MAX4004’s output current can
be referenced as desired with either a resistor to
ground or a transimpedance amplifier. Take care to
ensure that output voltage excursions do not interfere
with the required margin between BIAS and OUT.
CURRENT
CLAMP
10x
BIAS
REF
CLAMP
OUT
1x
GND
MAX4004
CURRENT
MONITOR
CURRENT
CLAMP
10x
BIAS
REF
CLAMP
OUT
1x
MAX4006
CURRENT
MONITOR
10kΩ
GND
MAX4004/MAX4006
In many fiber applications, OUT is connected directly to
an ADC that operates from a supply voltage that is less
than the voltage at BIAS. Connecting the
MAX4004/MAX4006’s clamping diode output, CLAMP,
to the ADC power supply helps avoid damage to the
ADC. Without this protection, voltages can develop at
OUT that can destroy the ADC. This protection is less
critical when OUT is connected directly to subsequent
transimpedance amplifiers (linear or logarithmic) that
have low-impedance, near-ground-referenced inputs. If
a transimpedance amp is used on the low side of the
photodiode, its voltage drop must also be considered.
Leakage from the clamping diode is most often insignif-
icant over nominal operating conditions, but grows with
temperature.
To maintain low levels of wideband noise, lowpass filter-
ing the output signal is suggested in applications where
only DC measurements are required. Determining the
required filtering components is straightforward, as the
MAX4004 exhibits a very high output impedance
(>5MΩ), while the MAX4006 exhibits an output resis-
tance of 10kΩ.
In some applications where pilot tones are used to iden-
tify specific fiber channels, higher bandwidths are
desired at OUT to detect these tones. Consider the mini-
mum and maximum currents to be detected, then con-
sult the frequency response and noise typical operating
curves. If the minimum current is too small, insufficient
monitor bandwidth could result, while too high of a cur-
rent could result in excessive monitor noise across the
desired bandwidth.
Bypassing and External Components
In applications where power-supply noise can interfere
with DC diode measurements, additional filtering is sug-
gested. Such noise is commonly seen when switching
power supplies are used to generate the photodiode
bias voltage. As shown in the typical operating circuit, a
pi filter (two 0.22µF capacitors and one 2.2µH inductor)
greatly suppress power-supply switching noise. If such
a filter is already present in the bias-generating circuit,
only a simple bypass capacitor at the BIAS pin is sug-
gested. The output lowpass filter, a 10kΩresistor and a
10nF capacitor, further reduce permeating power-sup-
ply noise as well as other wideband noise that might
otherwise restrict measurements at low signal levels.
Again, reducing the bandwidth of the OUT signal can
affect performance of pilot-tone systems.
To restrict high-frequency photodiode signals from
affecting the current monitor and BIAS power supply, an
RF choke and 10nF capacitor can be added. The
capacitance presented to REF should not exceed 10nF;
larger values increase startup time and could cause the
thermal shutdown circuit to activate during startup.
High-Accuracy, High-Side Current Monitors
in SOT23
8_______________________________________________________________________________________
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
_______________________________________________________________________________________ 9
Chip Information
Typical Operating Circuit
CURRENT
CLAMP
PIN
PHOTODIODE
+2.7V TO +22V 2.2µH
0.22µF
10nF
10kΩ
0.22µF
10x
BIAS
REF
CLAMP
OUT
1x
ADC
TIA
GND
+5V
+5V
TO LIMITING
AMPLIFIER
HIGH-SPEED DATA PATH
MAX4004
CURRENT
MONITOR
TRANSISTOR COUNT: 195
PROCESS: BiCMOS
MAX4004/MAX4006
High-Accuracy, High-Side Current Monitors
in SOT23
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
©2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
6LSOT.EPS
PACKAGE OUTLINE, SOT 6L BODY
21-0058
1
1
G
