PC87591L datasheet(170/437 Pages) NSC

170 / 437 page

Embedded Controller Modules (Continued)

www.national.com

170

Revision 1.07

4.11 ANALOG TO DIGITAL CONVERTER (ADC)

The Analog to Digital Converter (ADC) monitors various voltages and temperatures in the system and reports their values

to the core.

The ADC can measure up to 10 external voltage inputs and four internal voltage sources, with 10-bit resolution. The internal

voltage sources measure the VDD,VCC,AVCC and VBAT supplies. VDD,VCC and AVCC are divided by 2 to allow both over-

voltage and undervoltage detection. The external voltage inputs support thermistor-based temperature measurement.

The ADC can measure up to two, diode-based temperature sources with 1oC resolution. The current generated by the ADC

module causes a voltage drop on a remote (external) or local (internal) diode. This voltage is measured by the ADC and

converted to temperature units. An Overtemperature Shutdown (OTS) interrupt becomes active when the temperature of the

internal diode exceeds a programmable limit.

The ADC executes cycles of one temperature and three voltage measurements, each assigned to a separate output chan-

nel. The temperature channel measures the two temperature sources (remote and local) in consecutive cycles. Each of the

three voltage channels measures one selected voltage input during the cycle.

4.11.1 Features

●

Voltage measurement

— Ten external voltage inputs and four internal power supply inputs

— 10-bit resolution

— 0 to 2.97V input voltage range

— High-impedance, ground-referenced inputs

— Enables thermistor-based temperature measurement

●

Diode-based temperature measurement

— one remote (external) diode input and one local (internal) diode

— 1oC/bit resolution

—

−40oC to +125oC range (using the remote diode)

— Open/short detection for the remote diode connection

— Hardware-monitored, local overtemperature detection

●

Internal high-precision reference

●

Digital reading output channels

— Three voltage buffers and one temperature buffer (diode)

— Input selection for each voltage channel

●

Sampling sequence and timing

— Three voltage and one temperature measurement within 100 ms.

— Cyclic measurement of the four output channels

— Separate enable for each channel

— Programmable conversion-start delay to guarantee input settling time

●

Polling- or interrupt-driven interface

●

Power consumption

— Zero current when disabled

— Low operating current

4.11.2 Functional Description

Inputs. The ADC has 16 inputs (AI0-13, AI15, AI16) divided in three groups:

●

External Voltage (AI0-9). These are either general-purpose, positive DC voltage sources or temperature-dependent

voltage generated by using a Negative/Positive Temperature Coefﬁcient (NTC/PTC) thermistor in a resistive divider.

●

Internal Voltage (AI10-13) These are internally connected to the supply voltages of the device (VDD,VCC,AVCC and

VBAT). Voltages higher than the full-scale voltage (VFS) are divided by 2, except for VBAT which is not divided in order

to minimize the current drain.

●

Diode-Based Temperature Inputs (AI15, AI16). These are temperature-dependent voltage drops, on a remote and a

local diode, caused by the ﬂow of a current generated by the ADC. Since the AI8 and AI9 voltage inputs use the

same package pins as the remote diode (DP, DN), only one option (voltages or diode) is available at a time.

PC87591L датащи(PDF) 170 Page - National Semiconductor (TI)

PC87591L датащи(HTML) 170 Page - National Semiconductor (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL