HT67F60 datasheet(159/242 Pages) HOLTEK

159 / 242 page

HT67F30/HT67F40/HT67F50/HT67F60

TinyPowerTM A/D Flash Type 8-Bit MCU with LCD & EEPROM

Rev. 1.50

158

March 06 , 2012

Rev. 1.50

159

March 06 , 2012

Comparators

Two independent analog comparators are contained within these devices. These functions offer

flexibility via their register controlled features such as power-down, polarity select, hysteresis etc. In

sharing their pins with normal I/O pins the comparators do not waste precious I/O pins if there

functions are otherwise unused.

Cn +

Cn -

Cn PO L

Cn OU T

Cn X

Cn SE L

Comparator

Comparator Operation

The device contains two comparator functions which are used to compare two analog voltages and

provide an output based on their difference. Full control over the two internal comparators is

provided via two control registers, CP0C and CP1C, one assigned to each comparator. The

comparator output is recorded via a bit in their respective control register, but can also be transferred

out onto a shared I/O pin. Additional comparator functions include, output polarity, hysteresis

functions and power down control.

Any pull-high resistors connected to the shared comparator input pins will be automatically

disconnected when the comparator is enabled. As the comparator inputs approach their switching

level, some spurious output signals may be generated on the comparator output due to the slow

rising or falling nature of the input signals. This can be minimised by selecting the hysteresis

function will apply a small amount of positive feedback to the comparator. Ideally the comparator

should switch at the point where the positive and negative inputs signals are at the same voltage

level, however, unavoidable input offsets introduce some uncertainties here. The hysteresis function,

if enabled, also increases the switching offset value.

Comparator Registers

There are two registers for overall comparator operation, one for each comparator. As corresponding

bits in the two registers have identical functions, they following register table applies to both

registers.

Name

Bit

CP0C

C0SEL

C0EN

C0POL

C0OUT

C0OS

—

C0HYEN

CP1C

C1SEL

C1EN

C1POL

C1OUT

C1OS

—

C1HYEN

Comparator Registers List

Comparator Interrupt

Each also possesses its own interrupt function. When any one of the changes state, its relevant

interrupt flag will be set, and if the corresponding interrupt enable bit is set, then a jump to its

relevant interrupt vector will be executed. Note that it is the changing state of the C0OUT or C1OUT

bit and not the output pin which generates an interrupt. If the microcontroller is in the SLEEP or

IDLE Mode and the Comparator is enabled, then if the external input lines cause the Comparator

output to change state, the resulting generated interrupt flag will also generate a wake-up. If it is

required to disable a wake-up from occurring, then the interrupt flag should be first set high before

entering the SLEEP or IDLE Mode.

HT67F60 Datasheet(PDF) 159 Page - Holtek Semiconductor Inc

HT67F60 Datasheet(HTML) 159 Page - Holtek Semiconductor Inc

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