Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - current control/management Current monitoring TDFN 14 (3x3)

General Description

The DS1842 integrates the discrete high-voltage com-

ponents necessary for avalanche photodiode (APD)

bias and monitor applications. A switch FET is used in

conjunction with an external DC-DC controller to create

a boost DC-DC converter. A current clamp limits cur-

rent through the APD and also features an external

shutdown. The device also includes a dual current mir-

ror to monitor the APD current.

Applications

APD Biasing

GPON Optical Network Unit and Optical Line

Transmission

Features

♦ 76V Maximum Boost Voltage

♦ Switch FET

♦ Current Monitor with a Wide 1µA to 2mA Range,

Fast 50ns Time Constant, and 10:1 and 5:1 Ratio

♦ 2mA Current Clamp with External Shutdown

♦ Multiple External Filtering Options

♦ 3mm x 3mm, 14-Pin TDFN Package with Exposed Pad

DS1842

76V, APD, Bias Output Stage with

Current Monitoring

________________________________________________________________

Maxim Integrated Products

Ordering Information

19-4557; Rev 1; 3/11

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.

PART TEMP RANGE PIN-PACKAGE

DS1842N+ -40°C to +85°C 14 TDFN-EP*

DS1842N+T&R -40°C to +85°C 14 TDFN-EP*

Pin Configuration appears at end of data sheet.

Denotes a lead(Pb)-free/RoHS-compliant package.

T&R = Tape and reel.

EP = Exposed pad.

DS1875

DS1842

COMP

MON3

GATE

GND

MIRIN

MIR1

CLAMP

MIROUT

3.3V

CURRENT MIRROR

CURRENT

LIMIT

MIR2

BULK

COMP

EXTERNAL MONITOR

TIA

APD

ROSA

Typical Application Circuit

Summary of content (7 pages)

PAGE 1
9-4557; Rev 1; 3/11 76V, APD, Bias Output Stage with Current Monitoring The DS1842 integrates the discrete high-voltage components necessary for avalanche photodiode (APD) bias and monitor applications. A switch FET is used in conjunction with an external DC-DC controller to create a boost DC-DC converter. A current clamp limits current through the APD and also features an external shutdown. The device also includes a dual current mirror to monitor the APD current.
PAGE 2
DS1842 76V, APD, Bias Output Stage with Current Monitoring ABSOLUTE MAXIMUM RATINGS Voltage Range on GATE and CLAMP Relative to GND...................................................-0.3V to +12V Voltage Range on MIRIN, MIROUT, MIR1, and MIR2 Relative to GND........................-0.3V to +80V Voltage Range on LX Relative to GND...................-0.3V to +85V Continuous Power Dissipation (TA = +70°C) TDFN (derate 24.4mW/°C above +70°C).................1951.2mW Operating Junction Temperature Range ......
PAGE 3
76V, APD, Bias Output Stage with Current Monitoring MIRIN CURRENT vs. TEMPERATURE (VMIRIN = 40V, IMIROUT = 250nA) 90 100 4 MIRIN CURRENT (mA) 80 1000 5 DS1842 toc02 DS1842 toc01 100 MIRIN CURRENT (μA) MIRIN CURRENT (μA) 10,000 MIRIN CURRENT vs. TEMPERATURE (VMIRIN = 40V, IMIROUT = 2mA) 70 60 50 40 30 DS1842 toc03 MIRIN vs. MIROUT CURRENT (VMIRIN = 40V) 20 3 2 1 10 0 1 10 100 10,000 1000 -20 0 20 40 60 80 MIROUT CURRENT (μA) TEMPERATURE (°C) MIR ERROR vs.
PAGE 4
Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) FET ON-RESISTANCE vs. DRAIN CURRENT FET DRAIN CURRENT vs. DRAIN VOLTAGE VGS = 2.5V VGS = 10V 600 6 VGS = 5V 500 IDS (mA) VGS = 3.0V 5 VGS = 3.6V DS1842 toc10 700 DS1842 toc09 7 RDSON (Ω) DS1842 76V, APD, Bias Output Stage with Current Monitoring VGS = 3.6V 400 VGS = 3.0V 300 200 4 100 VGS = 5V VGS = 2.
PAGE 5
76V, APD, Bias Output Stage with Current Monitoring CLAMP REF The mirror response time is dominated by the amount of capacitance placed on the output. For burst-mode Rx systems where the fastest response times are required (approximately a 50ns time constant), a 3.3pF capacitor and external op amp should be used to buffer the signal sent to the ADC. For continuous mode applications, a 10nF capacitor is all that is required on the output. Current Clamp Figure 1.
PAGE 6
76V, APD, Bias Output Stage with Current Monitoring DS1842 Pin Configuration TOP VIEW 1 MIR2 2 N.C. 3 N.C. 4 CLAMP 5 GATE 6 14 MIROUT + MIR1 13 MIRIN 12 N.C. DS1842 11 N.C. 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.
PAGE 7
6V, APD, Bias Output Stage with Current Monitoring REVISION NUMBER REVISION DATE 0 4/09 Initial release 3/11 Updated the Absolute Maximum Ratings section; added the Package Thermal Characteristics section; changed pin 3 from GND to N.C. in the Pin Description and Pin Configuration 1 DESCRIPTION PAGES CHANGED — 2, 4, 6 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.