DS1842A View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
DS1842A Datasheet PDF : 6 Pages
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TOP VIEW
MIR1 1
MIR2 2
GND 3
FBOUT 4
CLAMP 5
GATE 6
PGND 7
*EXPOSED PAD.
76V, APD, Bias Output Stage with
Current Monitoring
Pin Configuration
Block Diagram
DS1842A
*EP
TDFN
14 MIROUT
13 MIRIN
12 FBIN
11 N.C.
10 N.C.
9 N.C.
8 LX
FBOUT
LX
GATE
PGND
CLAMP
DS1842A
R1
R2
CURRENT MIRROR
CURRENT
LIMIT
THERMAL
SHUTDOWN
FBIN
MIRIN
MIR1
MIR2
EP GND
MIROUT
PIN
1
2
3
4
5
6
7
8
9, 10, 11
12
13
14
—
NAME
MIR1
MIR2
GND
FBOUT
CLAMP
GATE
PGND
LX
N.C.
FBIN
MIRIN
MIROUT
EP
Pin Description
FUNCTION
Current Mirror Monitor Output, 10:1 Ratio
Current Mirror Monitor Output, 5:1 Ratio
Ground Connection for Device. Connect directly to ground plane. Connect GND to PGND at a
single point. See the Layout Considerations section for more information.
Feedback Output. Resistor-divider output.
Clamp Input. Disables the current mirror output (MIROUT).
FET Gate Connection
Source of Switch FET. Also connect to boost converter’s input and output capacitors. Connect
PGND to GND at a single point. See the Layout Considerations section for more information.
FET Drain Connection. Connect to switching inductor.
No Connection
Feedback Input. Resistor-divider input.
Current Mirror Input
Current Mirror Output. Connect to APD bias pin.
Exposed Pad. Connect directly to the same ground plane as GND.
Detailed Description
The DS1842A contains discrete high-voltage compo-
nents required to create an APD bias voltage and to
monitor the APD bias current. The device’s mirror out-
puts are a current that is a precise ratio of the output
current 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 APDs. The
APD current can also be shut down by CLAMP or ther-
mal shutdown. The internal FET and resistor-divider are
used in conjunction with a DC-DC boost controller to
precisely create the APD bias voltage.
Current Mirror
The DS1842A has two current mirror outputs. One is a
10:1 mirror connected at MIR1, and the other is a 5:1
mirror connected to MIR2.
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