HT13R90

Rev. 1.10

4

July 10, 2007

Functional Description

Power On & Reset

The HT13R90 has four different operating states,

namely the POR state, the standby state, the running

state and the wait state. The wait state can only be en-

tered when the Operating Mode bits, known as OMOD,

have a value of either 01 or 10. The POR state is the

Power on state, during which the device internal clock

will be used to load the configuration options. When the

device is in the POR state, the output pins, LED0, LED1

and LED2, will remain in a tri-state condition.

After the POR state has completed, if the RESET pin re-

mains low, the device will then enter the standby state.

In this state, the output pins will remain in an inactive

state according to the configuration option settings.The

accompanying timing diagram gives more details. For

the general case, the oscillator will cease running to re-

duce power, however the configuration options can also

be set to keep the oscillator running in the standby mode

in order to reduce the oscillator startup time.

In modes 01 and 10, after the counting ends, the device

will enter the wait state, which is different from what will

happen if the RESET line goes low. The wait state en-

compasses the same behavior as the standby state.

When the RESET line returns high, the device will enter

the running state. At the beginning of this state, the con-

figuration options will be loaded, which will initiate a re-

set, switch to the defined oscillator and start running.

R E S E T

T r i - s t a t e

R u n n i n g S t a t e

P O R S t a t e

( L o a d O p t i o n )

S t a n d b y S t a t e

R u n n i n g S t a t e

S t a n d b y

S t a t e

L o a d O p t i o n

T r i - s t a t e

T r i - s t a t e

T r i - s t a t e

L o a d O p t i o n

L E D 0

( O A C T = 1 )

L E D 0

( O A C T = 0 )

L E D 1 / 2

( L x A C T = 1 )

L E D 1 / 2

( L x A C T = 0 )

For all OMOD

R E S E T

T r i - s t a t e

R u n n i n g S t a t e

P O R S t a t e

( L o a d O p t i o n )

S t a n d b y S t a t e

R u n n i n g S t a t e

S t a n d b y

S t a t e

L o a d O p t i o n

L E D 0

( O A C T = 1 )

L E D 0

( O A C T = 0 )

T r i - s t a t e

T r i - s t a t e

T r i - s t a t e

L E D 1 / 2

( L x A C T = 1 )

L E D 1 / 2

( L x A C T = 0 )

L o a d O p t i o n

W a i t

S t a t e

For OMOD = 01 and 10