MAX1932ETC+T Maxim Integrated Products, MAX1932ETC+T Datasheet

IC SUPPLY BIAS APD 12-TQFN

MAX1932ETC+T

Manufacturer Part Number
MAX1932ETC+T
Description
IC SUPPLY BIAS APD 12-TQFN
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of MAX1932ETC+T

Applications
Controller, Fiber Optic Network
Voltage - Input
2.7 ~ 5.5 V
Number Of Outputs
1
Voltage - Output
4.5 ~ 90 V
Operating Temperature
0°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
12-TQFN Exposed Pad
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
The MAX1932 generates a low-noise, high-voltage output
to bias avalanche photodiodes (APDs) in optical
receivers. Very low output ripple and noise is achieved by
a constant-frequency, pulse-width modulated (PWM)
boost topology combined with a unique architecture that
maintains regulation with an optional RC or LC post filter
inside its feedback loop. A precision reference and error
amplifier maintain 0.5% output voltage accuracy.
The MAX1932 protects expensive APDs against adverse
operating conditions while providing optimal bias.
Traditional boost converters measure switch current for
protection, whereas the MAX1932 integrates accurate
high-side current limiting to protect APDs under
avalanche conditions. A current-limit flag allows easy cali-
bration of the APD operating point by indicating the pre-
cise point of avalanche breakdown. The MAX1932 control
scheme prevents output overshoot and undershoot to
provide safe APD operation without data loss.
The output voltage can be accurately set with either
external resistors, an internal 8-bit DAC, an external
DAC, or other voltage source. Output span and offset
are independently settable with external resistors. This
optimizes the utilization of DAC resolution for applica-
tions that may require limited output voltage range, such
as 4.5V to 15V, 4.5V to 45V, 20V to 60V, or 40V to 90V.
19-2555; Rev 1; 12/02
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.
Optical Receivers and Modules
Fiber Optic Network Equipment
Telecom Equipment
Laser Range Finders
PIN Diode Bias Supply
SCLK
DIN
CL
________________________________________________________________ Maxim Integrated Products
1
2
3
12
4
General Description
MAX1932
11
5
Pin Configuration
Digitally Controlled, 0.5% Accurate,
10
6
Applications
9
8
7
GND
COMP
FB
Safest APD Bias Supply
♦ Small Circuit Footprint
♦ Circuit Height < 2mm
♦ 2.7V to 5.5V Input
♦ 4.5V to 90V Output
♦ No Overshoot
♦ Accurate High-Side Current Limit
♦ Avalanche Indicator Flag
♦ 8-Bit SPI-Compatible DAC
♦ Compatible with External DAC
♦ 0.5% Accurate Output
♦ Low Ripple Output (< 1mV)
♦ Small 12-Pin, 4mm
MAX1932ETC
DAC INPUTS
AVALANCHE
INDICATOR
2.7V TO 5.5V
PART
INPUT
FLAG
Typical Application Circuit
COMP
CS
SCLK
DIN
CL
GND
-40°C to +85°C 12 Thin QFN
TEMP RANGE PIN-PACKAGE
MAX1932
DACOUT
VIN
Ordering Information
GATE
CS+
CS-
FB
4mm Thin QFN Package
Features
APD BIAS OUTPUT
4.5V TO 90V
1

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MAX1932ETC+T Summary of contents

Page 1

... MAX1932 ________________________________________________________________ Maxim Integrated Products 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. Safest APD Bias Supply ♦ Small Circuit Footprint ♦ Circuit Height < 2mm ♦ 2.7V to 5.5V Input ♦ 4.5V to 90V Output ♦ ...

Page 2

Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply ABSOLUTE MAXIMUM RATINGS VIN to GND...............................................................-0.3V to +6V DIN, SCLK, CS GND ......................................-0.3V to +6V COMP, DACOUT, GATE GND ...........-0. CS+, CS- to GND .................................................-0.3V to ...

Page 3

Digitally Controlled, 0.5% Accurate, ELECTRICAL CHARACTERISTICS (continued) = 3.3V SCLK = 3.3V, CS+ = CS- = 45V, Circuit of Figure PARAMETER SYMBOL DIGITAL INPUTS (DIN, SCLK, CS) Input Low Voltage Input ...

Page 4

Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply ELECTRICAL CHARACTERISTICS (continued) = 3.3V SCLK = 3.3V, CS+ = CS- = 45V, Circuit of Figure PARAMETER SYMBOL FB Voltage FB to COMP ...

Page 5

Circuit of Figure SWITCHING WAVEFORMS MAX1932 toc01 RIPPLE (AC-COUPLED) OUT V = 90V OUT 1μs/div OUTPUT VOLTAGE vs. INPUT VOLTAGE 2.5 3.5 4.5 ...

Page 6

Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply PIN NAME 1 SCLK DAC Serial Clock Input 2 DIN DAC Serial Data Input CL Current-Limit Indicator Flag indicates that the part is in current limit. Logic high level ...

Page 7

Digitally Controlled, 0.5% Accurate, Output and DAC Adjustments Range Many biasing applications require an adjustable output voltage, which is easily obtained using the MAX1932’s DAC output (Figure 2). The DAC output voltage is given by the following equation: ⎛ 1 ...

Page 8

Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply (<10pF) are recommended to minimize losses. A small- signal silicon switching diode is suitable if efficiency is not critical. Output Filter Capacitor Selection The output capacitors of the MAX1932 must have high ...

Page 9

Digitally Controlled, 0.5% Accurate, Table 1. Compensation Components for Typical Circuits (Figure 2) INDUCTOR OUT OUT(MAX) (µ 40-90V at 2.5mA 100 IN OUT 5V , 20-60V at 2.5mA 150 IN OUT ...

Page 10

Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply COMP REF 1.25V FB 987kΩ CS+ 987kΩ CS- SCLK 8 SPI SERIAL DIN INTERFACE CS Figure 1. Functional Diagram 10 ______________________________________________________________________________________ UVLO ERROR AMPLIFIER ERROR COMPARATOR RAMP OSC CLIM 13kΩ 13kΩ REF ...

Page 11

Digitally Controlled, 0.5% Accurate, 2.7V TO 5.5V R7 20kΩ C4 0.22μF Figure 2. Typical Operating Circuit GATE FB MAX1932 CS+ CS- Figure 3. Taking Feedback Ahead of Output Filter ______________________________________________________________________________________ Safest APD Bias Supply C1 1μF INPUT L1 VIN CL ...

Page 12

Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply CS t CSH0 t CSS0 SCLK t DS DIN Figure 5. Detailed Serial Interface Timing Diagram 12 ______________________________________________________________________________________ CSW t CSH1 t CSS1 ...

Page 13

Digitally Controlled, 0.5% Accurate, 120 100 0.01 Figure 6. Loop Response ______________________________________________________________________________________ Safest APD Bias Supply 90V, 1mA POLE1 0.0023Hz ZERO1 36Hz POLE2 36Hz POLE3 4.2kHz A 102dB OL 0.1 1.0 10 FREQUENCY (Hz) 90V, 2.5mA ...

Page 14

Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply MAX1932 Figure 7. Adding a Post LC Filter Figure 8. Adding an NTC Thermistor for Hardware Temperature Compensation; Output Voltage Increases with Temperature Rise 14 ______________________________________________________________________________________ VIN GATE FB CS+ CS- VIN ...

Page 15

Digitally Controlled, 0.5% Accurate, (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information www.maxim-ic.com/packages.) ______________________________________________________________________________________ Safest APD Bias Supply Package Information PACKAGE OUTLINE, 12, 16, 20, 24, ...

Page 16

... 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. 16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products ...

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