pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 170

• Manufacturer Part Number: pc87591l
• Description: Lpc Mobile Embedded Controllers
• Manufacturer: National Semiconductor Corporation

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Embedded Controller Modules
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 V
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 1
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
4.11.2 Functional Description
Inputs. The ADC has 16 inputs (AI0-13, AI15, AI16) divided in three groups:
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
— 1
—
— 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
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 (V
V
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.
BAT
). Voltages higher than the full-scale voltage (V
o
40
C/bit resolution
o
C to +125
o
C range (using the remote diode)
DD
, V
CC
, AV
CC
(Continued)
and V
BAT
FS
supplies. V
) are divided by 2, except for V
170
DD
, V
CC
o
C resolution. The current generated by the ADC
and AV
CC
are divided by 2 to allow both over-
BAT
which is not divided in order
DD
, V
CC
, AV
Revision 1.07
CC
and