NE1619 View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

NE1619

HECETA4 Temperature and voltage monitor

Philips Electronics 

Philips Semiconductors

HECETA4 Temperature and voltage monitor

Product data sheet

NE1619

Temperature data is represented by a digital 8-bit byte or word in

two’s complement format with a resolution of 1 °C. Theoretically, the

temperature value can be from –128 °C to +127 °C but, practically,

the operation range is limited to (0 °C, 120 °C). Here are some of

temperature values and data:

Table 8.

TEMPERATURE VALUE (°C)

+127

+126

+100

+25

+1

0

–1

–25

–50

TEMPERATURE DATA

0111 1111

0111 1110

0110 0100

0001 1001

0000 0001

0000 0000

1111 1111

1110 0111

1100 1110

Voltage measurement

The NE1619 provides 5 analog inputs for directly monitoring the

power supplies typically found in a PC or multiservice equipment,

having nominal values of +2.5 V, +3.3 V, +5.0 V, +12.0 V and VCCP

(2.25 V). The device also monitors its own VDD whose nominal

value is 3.3 V. Note: at power-up, the device Pin 11 is defaulted to its

12VIN function. These inputs are internally attenuated by on-chip

resistor networks to the reference levels that are then multiplexed to

a 8-bit Delta-Sigma A-to-D converter for converting into digital data.

Each VIN input is overall scaled in such a way that the decimal value

of the data for its nominal voltage value is equal to 192. It means

that the overall step size of the conversion for each VIN is equal to

1/192 of its nominal value. Reading data are stored in the VIN reading

registers and are also compared with the limits stored in the VIN limit

registers in order to set the voltage flag bits in the status registers as

described in Tables 3 and 4.

The VIN data, different from the temperature data, is represented by

a digital 8-bit byte or word in straight format with a resolution LSB

equal to 1/192 of the nominal value, and has any value from 0 to 255.

This is how to calculate the VIN error from the VIN reading at any

input including VDD:

Resolution in volts:

Full scale in volts:

LSB = (VIN nominal in volt)/192

FS= 255 * LSB

Reading value in volts: VIN value =

(decimal value of VIN reading) * LSB

Reading error in volts: VIN error = (VIN value) – (VIN applied)

VIN error in % of FS: VIN error % = 100*(VIN error)/FS

Applied value < 0 results in a reading of about 0

Applied value > FS results in a reading of about 255

Input safety

Since the power supply voltages will appear directly at VIN pins, a

small external resistor, about 500 Ω, should be connected in series

with each pin in order to prevent damaging the power supplies due

to accidental short. These resistors are recommended but not

necessary. No external resistor-divider should be used for the VIN

pins because of the effect of the internal input resistors, about

140 kΩ at each pin, on the divider accuracy.

Processor Voltage ID (VID)

The NE1619 provides 5 digital pins (VID0–VID4) to read the

processor voltage ID code and store it into the VID registers so that

the code can be read over the SMBus:

VID register: bit 0–bit3 reflect VID0–VID3 respectively

VID4 register: bit 0

reflects VID4

Because the VID4 function of 12VIN/VID4 pin (Pin 11) is not selected

at power-up (default function of this pin is 12VIN), the process of

selecting this pin must be performed, if VID4 is needed, by setting

(to 1) bit 5 (12VIN/VID4 SELECT) of the configuration register.

The default value of bit 0 of the VID4 register is 0.

The VID inputs should not be left floating because they are not

internally biased. If they are not used then they should be connected

to either GND or VDD with resistors.

Limit data

High and Low limits for temperatures and voltages should be

programmed into the limit registers using the format as described

above. During monitoring cycle, the measured data is automatically

compared with the limits and flag bits in the status registers are set

accordingly to the results. The assignment of the status bits are

listed in Tables 3 and 4.

Status registers

Results of limits comparisons are reflected by status or flag bits

stored in the status register 1 and 2. If the reading is within the limits

then the corresponding flag bit will be cleared to 0. Otherwise, it will

be set to 1. Status data can be read over the SMBus. Notice that

because the flag bits are automatically updated at every monitoring

cycle, their states only reflect the last measurements.

Diode fault status

The hardware connection at the diode pins (D+ and D–) are also

checked at the measurement of external temperature and the fault

condition is indicated by the flag bit 6 of the status register 2. This bit

is set to 1 if either short or open circuit fault is detected.

RESET output function

The NE1619 Pin 16 can be selected as a reset pulse output. When

this function is selected and the reset pulse is initiated, this pin will

output a single (minimum 20 ms) low state pulse.

The reset output function is selected by setting (to 1) the RESET

ENABLE bit (bit 7) of the VID register. Thereafter, the reset pulse is

generated whenever the RESET bit (bit 4) of the configuration

register is programmed to change from 0 to 1.

Because Pin 16 becomes an open-drain output when it is selected

as an output, an external pull-up resistor, about 100 kΩ is needed

for the output operation. This will restrict the address function on

Pin 16 to being high at power-up. Therefore, if multiple NE1619’s

are connected on the same bus, only one can have this function

enabled at one time.

2004 Oct 05

13

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