Datasheet

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DS3920

Fast Current Mirror

Typical Application Circuit

19-5797; Rev 2; 12/11

General Description

The DS3920 precision current mirror is designed for ava-

lanche photodiode (APD) and PIN photodiode biasing

and monitoring applications. The device offers a current

clamp to limit current through the APD and a current mir-

ror 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.

The device accepts a +2.97V to +76V current mirror

supply voltage. Internal current limiting (4.4mA 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.

The device is available in a 6-pin SOT23 package, and

operates over the -40NC to +85NC extended temperature

range.

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 (4.4mA or 20mA, typ)

S Voltage Clamp Protects Subsequent Output Circuitry

S 6-Pin SOT23 (MAX4007 Compatible)

Applications

Avalanche Photodiode (APD) Biasing

PIN Photodiode Monitoring

GEPON, GPON, 10GEPON, XGPON: ONU and OLT

Ordering Information appears at end of data sheet.

For related parts and recommended products to use with this part, refer to: www.maximintegrated.com/DS3920.related

DS3920

MIROUT

THERMAL

SHUTDOWN

CURRENT

MONITOR

CURRENT

LIMIT

MIROUT

MIRIN

DIODE

3.3V

APD BIAS

MIR

MIROUT

APD

ROSA

GND

OUT

AGC

499Ω

FILTER

0.1μF

OUT

1kΩ–5kΩ

FILTER

100Ω–1000Ω

TIA

For pricing, delivery, and ordering information, please contact Maxim Direct at

1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

Summary of content (7 pages)

PAGE 1
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.
PAGE 2
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.............................
PAGE 3
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.
PAGE 4
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.
PAGE 5
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.
PAGE 6
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.
PAGE 7
DS3920 Fast Current Mirror Revision History REVISION NUMBER REVISION DATE 0 3/11 Initial release 1 8/11 Changed the MIROUT -002 version current limit value from 2.9mA (typ) to 4.4mA (typ); updated the Electrical Characteristics IMIROUT values for -002 version from 2mA (min), 2.9mA (typ), 4.4mA (max) to 2.8mA (min), 4.