Rainbow Electronics MAX6683 - Manual (Page 7)

ten to the Serial Address Register. This code overwrites
the code set by connection of the ADD pin, until the
MAX6683 is taken through a POR cycle.
ADC and Multiplexer
The ADC integrates over a 66ms period, an integral
multiple of the line period with excellent noise rejection.
The internal oscillator is trimmed to produce a 66ms
conversion time for temperature and 33ms for each
voltage. This is equivalent to 4 and 2 cycles of 60Hz,
respectively, and provides protection against noise
pickup from the main supply. The internal oscillator fre-
quency can be changed to provide the same protection
against 50Hz by setting bit 7 in the Configuration
Register to 1 (Table 4). The multiplexer automatically
sequences through the inputs, measuring voltages and
temperature.
Low-Power Shutdown Mode
Setting bit 0 in the Configuration Register to zero stops
the monitoring loop and puts the MAX6683 into low-
power shutdown mode. In this mode, the SMBus/I
2 C
interface remains active, and the supply current drops
to 10µA or less.
Power-On Reset
The MAX6683 POR supply voltage is typically 2V.
Below this supply voltage, all registers are reset, the
device is put into shutdown mode, and the SMBus/I
2 C
interface is inactive.
Alarm Threshold Registers
Two registers, a hot temperature limit (T HOT ) at 39h and
a hot temperature hysteresis (T HYST ) at 3Ah, store
alarm threshold data (Table 1). If a measured tempera-
ture exceeds the value of T
HOT , an ALERT is asserted.
Alerts are cleared and reasserted depending on
the interrupt mode selected in the Temperature
Configuration Register (see
ALERT Interrupts).
MAX6683
Temperature Sensor and System Monitor
in a 10-Pin µMAX
_______________________________________________________________________________________ 7
Table 3. Voltage Data Format
ADC OUTPUT
CODE
INPUT VOLTAGE
AT 1.8V IN
INPUT VOLTAGE
AT 2.5V IN
INPUT VOLTAGE
AT 5V IN
V CC = +3.3V
LSB weight 9.375mV (1.8V/192) 13mV (2.5V/192) 26mV (5V/192) 17.2mV (3.3V/192)
0 < 9.375mV < 13mV < 26mV —
1 9.375mV to 18.75mV 13mV to 26mV 26mV to 52mV —
2 18.75mV to 28.125mV 26mV to 39mV 52mV to 78mV —
— — — — —
64 (1/4 scale) 600mV to 609.4mV 833mV to 846mV 1.664V to 1.692V —
— — — — —
128 (1/2 scale) 1.2V to 1.2094V 1.667V to 1.680V 3.330V to 3.560V —
— — — — —
192 (3/4 scale) 1.8V to 1.737V 2.5V to 2.513V 5V to 5.026V 3.3V to 3.317V
— — — — —
253 2.372V to 2.381V 3.294V to 3.307V 6.566V to 6.640V 4.348V to 4.366V
254 2.381V to 2.391V 3.572V to 3.586V 6.615V to 6.640V 4.366V to 4.383V
255 = 2.391V = 3.586V = 6.640V = 4.383V
Table 2. Temperature Data Format
(Two's Complement)
HIGH BYTE
TEMPERATURE
(°C)
DIGITAL OUTPUT
(BINARY)
DIGITAL OUTPUT
(HEX)
+125 0111 1101 7D
+25 0001 1001 19
+1 0000 0001 01
0 0000 0000 00
-1 1111 1111 FF
-25 1110 0111 E7
-40 1101 1000 D8
LOW BYTE
0.875 1110 0000 D0
0.125 0010 0000 20