Datasheet

Dual, Temperature-Controlled Resistors with Inter-
nally Calibrated Monitors and Password Protection
8 Maxim Integrated
DS1856
Detailed Description
The user can read the registers that monitor the V
CC
,
MON1, MON2, MON3, and temperature analog signals.
After each signal conversion, a corresponding bit is set
that can be monitored to verify that a conversion has
occurred. The signals also have alarm and warning flags
that notify the user when the signals go above or below
the user-defined value. Interrupts can also be set for
each signal.
The position values of each resistor can be indepen-
dently programmed. The user can assign a unique
value to each resistor for every 2°C increment over the
-40°C to +102°C range.
Two buffers are provided to convert logic-level inputs
into open-drain outputs. Typically, these buffers are
used to implement transmit (Tx) fault and loss-of-signal
(LOS) functionality. Additionally, OUT1 can be asserted
in the event that one or more of the monitored values
go beyond user-defined limits.
PIN
BALL NAME
FUNCTION
1B2
SDA
2-Wire Serial Data I/O Pin. Transfers serial data to and from the device.
2 A2 SCL 2-Wire Serial Clock Input. Clocks data into and out of the device.
3C3
OUT1
Open-Drain Buffer Output
4 A1 IN1 TTL/CMOS-Compatible Input to Buffer
5B1
OUT2
Open-Drain Buffer Output
6 C2 IN2 TTL/CMOS-Compatible Input to Buffer
7C1
N.C.
No Connection
8D1
GND
Ground
9D3
MON1
External Analog Input
10 D4
MON2
External Analog Input
11 C4
MON3
External Analog Input
12 D2 L0
Low-End Resistor 0 Terminal. It is not required that the low-end terminals be connected to a potential
less than the high-end terminals of the corresponding resistor. Voltage applied to any of the resistor
terminals cannot exceed the power-supply voltage, V
CC
, or go below ground.
13 B3 H0
High-End Resistor 0 Terminal. It is not required that the high-end terminals be connected to a
potential greater than the low-end terminals of the corresponding resistor. Voltage applied to any of
the resistor terminals cannot exceed the power-supply voltage, V
CC
, or go below ground.
14 B4 L1 Low-End Resistor 1 Terminal
15 A4 H1 High-End Resistor 1 Terminal
16 A3 V
CC
Supply Voltage
Pin Description