1°C Triple Temperature Sensor with Resistance Error Correction & Hotter of Two Zones

Datasheet

Revision 1.44 (04-14-08)

12

SMSC EMC1053

DATASHEET

3.3.1

Conversion Rates

The EMC1053 may be configured for different conversion rates based on the system requirements.

The available rates are 1 full set of conversions per second to 16 full sets of conversions per second.

The conversion rate is configured as described in Section 4.4. The available conversion rates are

shown in Table 4.4.

3.3.2

Dynamic Averaging

The EMC1053 temperature channels support a new feature that measures the external diode channels

for an extended time based on the selected conversion rate. This functionality can be disabled as

described in Section 4.5 for increased power savings at the lower conversion rates. When Dynamic

Averaging is enabled, the device will automatically adjust the sampling and measurement time for both

external diode channels. This allows the device to average 2x or 4x longer than the normal 11 bit

operation while still maintaining the selected conversion rate. The benefits of Dynamic Averaging are

improved noise rejection due to the longer integration time as well as less random variation on the

temperature measurement.

The Dynamic Averaging applies when a One-Shot command is issued. The device will perform the

desired averaging during the one-shot operation according to the selected conversion rate.

The Dynamic Averaging will affect the average supply current based on the chosen conversion rate

as shown in Table 3.1.

3.4

Temperature Monitors

In general, thermal diode temperature measurements are based on the change in forward bias voltage

of a diode when operated at two different currents. This

ΔV

temperature as shown in the following equation:

Table 3.1 Supply Current vs. Conversion Rate and ADC Averaging Factor

CONVERSION RATE

ADC AVERAGING FACTOR

4X

(MAX_RES = 1)

(DA_N = 0)

2X

(MAX_RES = 0)

(DA_N = 0)

1X

(DA_N = 1)

1 / sec

190uA

132uA

105uA

2 / sec

315uA

205uA

150uA

4 / sec

580uA

350uA

235uA

8 / sec

N/A

640uA

405uA

16 / sec

N/A

N/A

750uA

where:

k = Boltzmann’s constant

T = absolute temperature in Kelvin

[1]

q = electron charge

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

=

−

=

Δ

LOW

HIGH

LOW

BE

HIGH

BE

BE

I

I

q

kT

V

V

V

ln

_

_

η