DS3920 Maxim, DS3920 Datasheet - Page 6

• Manufacturer Part Number: DS3920
• Description: The DS3920 precision current mirror is designed for avalanche photodiode (APD) and PIN photodiode biasing and monitoring applications
• Manufacturer: Maxim

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 shut-
down. A diode is provided to limit the voltage at the MIR
output.
The mirror output is typically connected to an analog-
to-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.
The mirror response time is dominated by the amount of
capacitance placed on the output.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
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.
DS3920T-001+
DS3920T-001+T
DS3920T-002+
DS3920T-002+T
PACKAGETYPE
6 SOT23
PART
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Detailed Description
PACKAGECODE
-40NC to +85NC
-40NC to +85NC
-40NC to +85NC
-40NC to +85NC
TEMPRANGE
Current Mirror
U6SN+1
TYPCURRENTLIMIT(mA)
The device features a current clamping circuit to protect
the photodiode by limiting the amount of current from
MIROUT to no more than I
Information
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 V
forward voltage drop, or V
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 T
shutdown mechanism has a built-in hysteresis of T
Thus, the MIROUT and MIR currents resume once the
device has cooled to T
OUTLINENO.
21-0058
4.4
4.4
20
20
for available current clamp options.
Fast Current Mirror
SHDN
Ordering Information
Package Information
MIR
PIN-PACKAGE
6 SOT23
6 SOT23
6 SOT23
6 SOT23
- T
MIROUT
- V
HYST
LANDPATTERNNO.
MIR
Thermal Shutdown
DF
Diode Protection
.
.
limit minus the diode
. See the
Current Clamp
90-0175
SHDN
DS3920
. The thermal
Ordering
HYST
.