MAX1932 Datasheet, PDF (1/16 Pages) Maxim Integrated Products – Digitally Controlled, 0.5% Accurate, Safest APD Bias Supply

19-2555; Rev 1; 12/02
Digitally Controlled, 0.5% Accurate, Safest APD
Bias Supply
General Description
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.
Applications
Optical Receivers and Modules
Fiber Optic Network Equipment
Telecom Equipment
Laser Range Finders
PIN Diode Bias Supply
Pin Configuration
12 11 10
SCLK 1
9 GND
DIN 2
CL 3
MAX1932
456
8 COMP
7 FB
Features
o Small Circuit Footprint
o Circuit Height < 2mm
o 2.7V to 5.5V Input
o 4.5V to 90V Output
o No Overshoot
o Accurate High-Side Current Limit
o Avalanche Indicator Flag
o 8-Bit SPI-Compatible DAC
o Compatible with External DAC
o 0.5% Accurate Output
o Low Ripple Output (< 1mV)
o Small 12-Pin, 4mm ✕ 4mm Thin QFN Package
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX1932ETC -40°C to +85°C 12 Thin QFN
Typical Application Circuit
INPUT
2.7V TO 5.5V
VIN
MAX1932
COMP
GATE
DAC INPUTS
AVALANCHE
INDICATOR
FLAG
CS
CS+
SCLK
CS-
DIN
CL
GND
FB
DACOUT
APD BIAS OUTPUT
4.5V TO 90V
________________________________________________________________ Maxim Integrated Products 1
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.