Dual, Temperature-Controlled Resistors with Inter-
nally Calibrated Monitors and Password Protection
General Description
The DS1856 dual, temperature-controlled, nonvolatile
(NV) variable resistors with three monitors consists of
two 256-position, linear, variable resistors; three analog
monitor inputs (MON1, MON2, MON3); and a direct-to-
digital temperature sensor. The device provides an
ideal method for setting and temperature-compensating
bias voltages and currents in control applications using
minimal circuitry. The variable resistor settings are
stored in EEPROM memory and can be accessed over
the 2-wire serial bus.
Relative to other members of the family, the DS1856 is
essentially a DS1859 with a DS1852-friendly memory
map. In particular, the DS1856 can be configured so
the 128 bytes of internal Auxiliary EEPROM memory is
mapped into Main Device Table 00h and Table 01h,
maintaining compatibility between both the
DS1858/DS1859 and the DS1852. The DS1856 also
features password protection equivalent to the DS1852,
further enhancing compatibility between the two.
Features
♦
SFF-8472 Compatible
♦
Five Monitored Channels (Temperature, V
CC
,
MON1, MON2, MON3)
♦
Three External Analog Inputs (MON1, MON2, MON3)
That Support Internal and External Calibration
♦
Scalable Dynamic Range for External Analog Inputs
♦
Internal Direct-to-Digital Temperature Sensor
♦
Alarm and Warning Flags for All Monitored
Channels
♦
Two Linear, 256-Position, Nonvolatile Temperature-
Controlled Variable Resistors
♦
Resistor Settings Changeable Every 2°C
♦
Three Levels of Security
♦
Access to Monitoring and ID Information
Configurable with Separate Device Addresses
♦
2-Wire Serial Interface
♦
Two Buffers with TTL/CMOS-Compatible Inputs and
Open-Drain Outputs
♦
Operates from a 3.3V or 5V Supply
♦
-40°C to +95°C Operating Temperature Range
DS1856
Applications
Optical Transceivers
Optical Transponders
Instrumentation and Industrial Controls
RF Power Amps
Diagnostic Monitoring
Ordering Information
PART
DS1856E-050
DS1856E-050/T&R
DS1856B-050
RES0/RES1
RESISTANCE
(kΩ)
50/50
50/50
50/50
PIN-PACKAGE
16 TSSOP
16 TSSOP
16-Ball CSBGA
Typical Operating Circuit
V
CC
V
CC
= 3.3V
4.7kΩ
2-WIRE
INTERFACE
Tx-FAULT
4.7kΩ
1
2
3
4
5
LOS
6
IN2
7
8
N.C.
GND
MON3
MON2
MON1
SDA
SCL
OUT1
IN1
OUT2
V
CC
H1
L1
H0
16
15
14
13
12
DECOUPLING
CAPACITOR
Ordering Information continued at end of data sheet.
+Denotes lead free.
*Future
product—contact factory for availability.
T&R denotes tape-and-reel.
All parts operate at the -40°C to +95°C temperature range.
0.1µF
Pin Configurations
TOP VIEW
A
SDA 1
IN1
SCL
V
CC
H1
SCL 2
OUT1 3
L1
IN1 4
16 V
CC
15 H1
14 L1
TO LASER BIAS
CONTROL
TO LASER
MODULATION
CONTROL
DS1856
L0
B
OUT2
SDA
H0
11 Rx POWER*
10 Tx POWER*
9 Tx BIAS*
DIAGNOSTIC
INPUTS
C
N.C.
IN2
OUT1
MON3
DS1856
13 H0
12 L0
11 MON3
10 MON2
9
MON1
OUT2 5
IN2 6
D
GND
1
L0
2
MON1
3
MON2
4
N.C. 7
GND 8
*SATISFIES SFF-8472 COMPATIBILITY
CSBGA (4mm x 4mm)
1.0mm PITCH
TSSOP
______________________________________________
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.
Dual, Temperature-Controlled Resistors with Inter-
nally Calibrated Monitors and Password Protection
DS1856
ABSOLUTE MAXIMUM RATINGS
Voltage Range on V
CC
Relative to Ground ...........-0.5V to +6.0V
Voltage Range on Inputs Relative
to Ground* ..............................................-0.5V to (V
CC
+ 0.5V)
Voltage Range on Resistor Inputs Relative
to Ground* ..............................................-0.5V to (V
CC
+ 0.5V)
Current into Resistors............................................................5mA
*Not
to exceed 6.0V.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Operating Temperature Range ...........................-40°C to +95°C
Programming Temperature Range .........................0°C to +70°C
Storage Temperature Range .............................-55°C to +125°C
Soldering Temperature .......................................See IPC/JEDEC
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