Rainbow Electronics DS1858 - Manual (Page 7)

Dual Temperature-Controlled Resistors with
Three Monitors
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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 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
1 B2 SDA 2-Wire Serial Data I/O Pin. This pin is for serial data transfer to and from the device.
2 A2 SCL 2-Wire Serial Clock Input. The serial clock input is used to clock data into and out of the device.
3 C3 OUT1 Open-Drain Buffer Output
4 A1 IN1 TTL/CMOS-Compatible Input to Buffer
5 B1 OUT2 Open-Drain Buffer Output
6 C2 IN2 TTL/CMOS-Compatible Input to Buffer
7 C1 WPEN
Write Protect Enable. The device is not write protected if WPEN is connected to ground. This pin has
an internal pullup (R
WPEN ). See Table 6.
8 D1 GND Ground
9 D3 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 Descriptions
DS1858