HT95R33 datasheet(39/59 Pages) HOLTEK

39 / 59 page

HT95R33

Rev. 1.10

February 18, 2009

PFD Data Register

Bit No.

Label

R/W

Function

7~0

PFD data register

PFDD (2FH) Register

PFD_Output_Frequency=

Prescaler_Output

2x(N 1)

, where N = the value of the PFD Data

RTC Function

When RTC 1000ms time-out occurs, the hardware will set the interrupt request flag RTCF and the RTCTO flag to 1.

When the interrupt service routine is serviced, the interrupt request flag (RTCF) will be cleared to 0, but the flag RTCTO

remains in its original values. This bit (RTCTO) should be cleared only by software. However, next RTC interrupt will

still occur, even though the RTCTO flag is not cleared.

Low Voltage Reset Functions

There is a low voltage reset circuit (LVR) implemented in the microcontroller. This function can be enabled/disabled by

options. Once the LVD options is enabled, the user can use the RTCC.3 to enable/disable (1/0) the LVD circuit and read

the LVD detector status (0/1) from RTCC.5; otherwise, the LVD function is disabled.

The microcontroller provides low voltage reset circuit in order to monitor the supply voltage of the device. If the supply

voltage of the device is within the range 0.9V~3.3V, such as changing a battery, the LVR will automatically reset the de-

vice internally.

The LVR includes the following specifications:

· The low voltage (0.9V~V

LVR) has to remain in their original state to exceed 1ms. If the low voltage state does not ex-

ceed 1ms, the LVR will ignore it and do not perform a reset function.

· The LVR uses the

²OR² function with the external RES signal to perform chip reset.

The relationship between VDD and VLVR is shown below.

5 . 5 V

3 . 0 V

2 . 2 V

0 . 9 V

V D D

V O P R

V L V R

5 . 5 V

R T C C R e g i s t e r

b 0

N o t i m p l e m e n t e d , r e a d a s " 0 "

b 7

R T C F u n c t i o n E n a b l e

1 : e n a b l e

0 : d i s a b l e

R T C T i m e - o u t F l a g

1 : R T C t i m e - o u t o c c u r s

0 : R T C t i m e - o u t d o e s n o t o c c u r

R T C E N

N o t i m p l e m e n t e d , r e a d a s " 0 "

R T C T O

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