Maxim DS3920T-001+ Fast current mirror voltage clamp protects subsequent output circuitry Datasheet

19-5797; Rev 0; 3/11
DS3920
Fast Current Mirror
General Description
The DS3920 precision current mirror is designed for avalanche photodiode (APD) and PIN photodiode biasing
and monitoring applications. The device offers a current
clamp to limit current through the APD and a current mirror output that produces a signal proportional (5:1) to the
APD current. A diode is also provided to limit the voltage
at the current mirror output.
Features
S Wide Voltage Input Range: 2.97V to 76V
S Current Monitor
 Wide 250nA to 2mA Range
 5:1 Mirror Ratio
 Fast 50ns Time Constant
S Current Clamp (2.9mA or 20mA, typ)
The device accepts a +2.97V to +76V current mirror
supply voltage. Internal current limiting (2.9mA or 20mA,
typ) protects the monitored device from a short circuit to
ground. The provided internal clamp diode protects the
current mirror output from overvoltage. Additionally, the
device features thermal shutdown if the die temperature
reaches +150NC.
S Voltage Clamp Protects Subsequent Output Circuitry
The device is available in a 6-pin SOT23 package, and
operates over the -40NC to +85NC extended temperature
range.
GEPON, GPON, 10GEPON, XGPON: ONU and OLT
S 6-Pin SOT23 (MAX4007 Compatible)
Applications
Avalanche Photodiode (APD) Biasing
PIN Photodiode Monitoring
Ordering Information appears at end of data sheet.
Typical Application Circuit
APD BIAS
RFILTER
3.3V
MIRIN
DIODE
CFILTER
0.1μF
CURRENT
MONITOR
IMIROUT
GND
IMIROUT/5
THERMAL
SHUTDOWN
MIR
CURRENT
LIMIT
DS3920
MIROUT
IMIROUT/5
VOUT
ROUT
RAGC
499Ω
ROSA
APD
TIA
For related parts and recommended products to use with this part, refer to: www.maxim-ic.com/DS3920.related
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For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
DS3920
Fast Current Mirror
ABSOLUTE MAXIMUM RATINGS
Voltage Range on MIRIN, MIROUT,
and DIODE Relative to GND .............................-0.3V to +80V
Voltage Range on MIR
Relative to GND .............................. -0.3V to (VDIODE + 0.6V)
Continuous Power Dissipation (TA = +70NC)
SOT23 (derate 13.4mW/NC above +70NC)..............1072.4mW
Operating Junction Temperature Range.......... -40NC to +150NC
Storage Temperature Range............................. -55NC to +135NC
Lead Temperature (soldering, 10s).................................+300NC
Soldering Temperature (reflow).......................................+260NC
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.
ELECTRICAL CHARACTERISTICS
(VMIRIN = 2.97V to 76V, TA = -40NC to +85NC, unless otherwise noted.)
PARAMETER
SYMBOL
MIRIN Voltage
VMIRIN
MIRIN Current
IMIRIN
Diode Forward Current
MIN
TYP
2.97
IMIROUT = 2.5mA
IDF
Diode Forward Voltage
VDF
MIROUT Current Limit
IMIROUT
MIROUT Series Resistance
CONDITIONS
RAGC
MAX
UNITS
76
V
4.4
mA
5
mA
0.6
IDF = 100FA, TA = +25NC
IDF = 5mA, TA = +25NC
1.25
DS3920T-001 version
10
20
40
DS3920T-002 version
2
2.9
4.4
(Note 1)
100
V
mA
W
1FA to 2.5mA
0.190
0.200
0.210
IMIROUT > 2.5mA
0.180
0.200
0.220
VMIRIN = 3V (Note 2)
4800
15,000
VMIRIN = 30V or 60V (Notes 2, 3)
100
500
tRC
(Note 4)
30
ns
Thermal Shutdown Temperature
TSHDN
(Note 3)
+150
NC
Thermal Shutdown Hysteresis
THYST
(Note 3)
20
NC
MIR to MIROUT Ratio
Power-Supply Rejection Ratio
MIR Current Rise Time
(20%/80%)
Note
Note
Note
Note
1:
2:
3:
4:
KMIR
(DIMIR/IMIR)
/DVMIRIN
A/A
ppm/V
See the Typical Application Circuit.
1V DC change applied to MIRIN; 100FA at MIROUT; 4.99kI load to ground on MIR.
Guaranteed by design; not production tested.
Rising MIROUT transition from 10FA to 1mA; 15V < VOUT < 76V.
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*The parametric values (min, typ, max limits) shown in the Electrical Characteristics table supersede values quoted elsewhere in this data sheet.
DS3920
Fast Current Mirror
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MIRIN CURRENT vs. MIRIN VOLTAGE
IMIROUT = 2.5mA
DS3920 toc02
MIRIN CURRENT vs. MIROUT CURRENT
100
DS3920 toc01
10
VMIRIN = 40V
10
IMIRIN (mA)
IMIRIN (mA)
1
0.1
1
IMIROUT = 1µA
0.1
0.01
0.001
0.01
20
40
60
80
0.01
VMIRIN (V)
MIRIN CURRENT vs. TEMPERATURE
1
10
GAIN ERROR vs. MIROUT CURRENT
5
DS3920 toc03
10
IMIROUT = 2.5mA
IMIRIN (mA)
IMIROUT = 1µA
VMIRIN = 40V
4
3
GAIN ERROR (%)
1
0.1
0.1
IMIROUT (mA)
DS3920 toc04
0
2
1
0
-1
-2
-3
-4
VMIRIN = 40V
0.01
-40
-15
10
35
60
-5
0.001
85
0.01
TEMPERATURE (°C)
DS3920 toc06
1.5
GAIN ERROR (%)
GAIN ERROR (%)
1
0
IMIROUT = 250µA
IMIROUT = 10mA
-2
0.5
IMIROUT = 1µA
IMIROUT = 2.5mA
0
IMIROUT = 5mA
-0.5
-1.0
-3
IMIROUT = 10mA
-1.5
-4
VMIRIN = 40V
-5
-40
-15
10
10
1.0
2
-1
2.0
DS3920 toc05
IMIROUT = 1µA
IMIROUT = 2.5mA
3
1
GAIN ERROR vs. MIRIN VOLTAGE
GAIN ERROR vs. TEMPERATURE
5
4
0.1
IMIROUT (mA)
35
TEMPERATURE (°C)
60
-2.0
85
0
20
40
60
80
VMIRIN (V)
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DS3920
Fast Current Mirror
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
TRANSIENT RESPONSE
(VMIRIN = 40V)
STARTUP DELAY
(VBIAS = 40V, IMIROUT = 1µA)
DS3920 toc07
STARTUP DELAY
(VMIRIN = 40V, IMIROUT = 2.5mA)
DS3920 toc08
40V
CH1
A
MIR
0V
R2
5kΩ
40V
CH1
CH1
MIRIN
D.U.T
DS3920 toc09
MIROUT
CH2
R1
38MΩ
CH1
MIR
0V
R2
5kΩ
MIRIN
D.U.T
MIROUT
CH2
R1
15.6kΩ
40V
MIR
CH2
B
MIRIN
D.U.T
MIROUT
CH1
CH2
CH2
0V
0V
5kΩ
100kΩ
5kΩ
500ns/div
200µs/div
A: CH1, 1V/div, IMIROUT = 375µA TO 7.5mA
A: CH2; 5V/div, IMIR = 75µA TO 1.5mA
200µs/div
CH1: 20V/div
CH2: 20V/div
CH1: 20V/div
CH2: 20V/div
STARTUP DELAY
(VMIRIN = 5V, IMIROUT = 1µA)
STARTUP DELAY
(VMIRIN = 5V, IMIROUT = 2.5mA)
DS3920 toc10
DS3920 toc11
5V
5V
CH1
CH1
MIR
R2
5kΩ
0V
CH2
MIRIN
D.U.T
CH1
CH1
MIROUT
CH2
R1
4.6MΩ
MIR
R2
5kΩ
0V
MIRIN
D.U.T
MIROUT
CH2
R1
1.7kΩ
CH2
0V
0V
200µs/div
CH1: 2V/div
CH2: 2V/div
200µs/div
CH1: 2V/div
CH2: 2V/div
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DS3920
Fast Current Mirror
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
SHORT-CIRCUIT RESPONSE
(VMIRIN = 76V)
DS3920 toc12
TA = +40°C
A
D E F
C
B
B
C
D E F
CH1
CH1
0A
0A
1.4
VMIRIN = 2.97V
1.2
VMIRIN - VMIROUT (V)
A
VOLTAGE DROP vs. MIROUT CURRENT
DS3920 toc13
TA = +40°C
1.0
0.6
20ms/div
CH1: IMIROUT, 5mA/div
A: MIROUT SHORTS TO GND THROUGH 10Ω
B: CURRENT LIMIT ACTIVE
C: THERMAL SHUTDOWN
D: POST COOL-DOWN REENTRY
E: THERMAL SHUTDOWN
F: POST COOL-DOWN REENTRY
+
DIODE
1
GND
2
MIR
3
DS3920
SOT23
TA = +100°C
TA = +85°C
0.01
0.1
1
10
100
IMIROUT (mA)
Pin Configuration
TOP VIEW
TA = +25°C
0.4
0
0.001
20ms/div
TA = -40°C
0.8
0.2
CH1: IMIROUT, 5mA/div
A: MIROUT SHORTS TO GND THROUGH 10Ω
B: CURRENT LIMIT ACTIVE
C: THERMAL SHUTDOWN
D: POST COOL-DOWN REENTRY
E: THERMAL SHUTDOWN
F: POST COOL-DOWN REENTRY
DS3920 toc14
SHORT-CIRCUIT RESPONSE
(VMIRIN = 40V)
Pin Description
PIN
NAME
FUNCTION
1
DIODE
Protection Diode. External potential used
for voltage clamping of VMIR. If unused,
this pin can be left unconnected.
6
MIRIN
2
GND
Ground
5
N.C.
3
MIR
Mirror Current Monitor Output, 5:1 Ratio
4
MIROUT
4
MIROUT
Current Mirror Voltage Output. Connect to
photodiode bias pin. Photodiode
provides reference current for the mirror.
5
N.C.
6
MIRIN
No Connection. Not internally
connected.
Current Voltage Bias
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DS3920
Fast Current Mirror
Detailed Description
The DS3920 provides a fast, precision current mirror for
photodiode-monitoring applications. The current mirror
is accurate across a large dynamic range. The mirror
response time is fast enough to comply with GPON Rx
burst-mode monitoring requirements. The device has a
built-in current limiting feature to protect photodiodes
from large signal inputs, and an included thermal shutdown. A diode is provided to limit the voltage at the MIR
output.
Current Mirror
The mirror output is typically connected to an analogto-digital converter (ADC) using a resistor to convert the
mirrored current into a voltage. The resistor to ground
should be selected so that the ADC’s full-scale voltage is
reached when the maximum mirrored current is reached.
For example, given that the maximum monitored current
through the APD is 2mA, 1.25V ADC full scale, and a 5:1
mirror ratio, the correct resistor is approximately 3.2kI.
Current Clamp
The device features a current clamping circuit to protect
the photodiode by limiting the amount of current from
MIROUT to no more than IMIROUT. See the Ordering
Information for available current clamp options.
Diode Protection
A diode is internally connected from the MIR to DIODE
pins. This enables an external voltage applied to DIODE
to limit the voltage on MIR. The voltage applied to DIODE
should be equal to the desired VMIR limit minus the diode
forward voltage drop, or VMIR - VDF.
Thermal Shutdown
As a safety feature, the device has a thermal shutdown
circuit that turns off the MIROUT and MIR currents when
the internal die temperature exceeds TSHDN. The thermal
shutdown mechanism has a built-in hysteresis of THYST.
Thus, the MIROUT and MIR currents resume once the
device has cooled to TSHDN - THYST.
The mirror response time is dominated by the amount of
capacitance placed on the output.
Ordering Information
TEMP RANGE
TYP CURRENT LIMIT (mA)
DS3920T-001+
PART
-40NC to +85NC
20
PIN-PACKAGE
6 SOT23
DS3920T-001+T
-40NC to +85NC
20
6 SOT23
DS3920T-002+
-40NC to +85NC
2.9
6 SOT23
DS3920T-002+T
-40NC to +85NC
2.9
6 SOT23
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Package Information
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains
to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
6 SOT23
U6SN+1
21-0058
90-0175
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DS3920
Fast Current Mirror
Revision History
REVISION
NUMBER
REVISION
DATE
0
3/11
DESCRIPTION
Initial release
PAGES
CHANGED
—
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.
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©
2011 Maxim Integrated Products
7
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