HT48R03 Holtek Semiconductor, HT48R03 Datasheet - Page 19

• Manufacturer Part Number: HT48R03
• Description: (HT48R01 - HT48R03) 10-Pin MSOP I/O Type 8-Bit OTP MCU
• Manufacturer: Holtek Semiconductor

Note: I: input; O: output; D, D
Note: *1: To make sure that the system oscillator has stabilised, the SST provides an extra delay of
Rev. 1.00
Buzzer Function
PA0 and PA1 are pin-shared with the BZ and BZ
buzzer signals, respectively. If the Buzzer option is se-
lected, then if these pins are setup as outputs, the sig-
nals on PA0 (or PA1) will be the Buzzer signal. If setup
as inputs, they will always retain their original input
functions.
The buzzer output signals (in output mode) are con-
trolled by the PA0 data register only. The truth table for
PA0/BZ and PA1/BZ are listed below. Port A also has
a CMOS or Schmitt trigger input configuration option
(All port A I/O lines are controlled by a option bit).
The truth table for PA0/BZ and PA1/BZ is as shown.
PA0 I/O
PA1 I/O
PA0 Mode
PA1 Mode
PA0 Data
PA1 Data
PA0 Pad Status I I I I D 0 B D
PA1 Pad Status I D 0 B I I I D
B: buzzer option, BZ or BZ; x: don't care
C: CMOS output
*2: Since the low voltage has to be maintained in its original state and exceed t
1024 system clock pulses before entering normal operation.
the reset mode.
x x x x C B B C B B B B
x C B B x x x C C C B B
x x 0 1 D 0 1 D
x D x x x x x D
I I I I O O O O O O O O
I O O O I I I O O O O O
0
, D
1
: data;
0
1
0
1
D D x x
D D 0 B
0 1 0 1
0 B 0 B
Low Voltage Reset
19
Low Voltage Reset - LVR
The microcontroller provides a 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~V
will automatically reset the device internally.
The LVR includes the following specifications:
The relationship between V
Note: V
The low voltage (0.9V~V
dition for a time greater than 1ms. If the low voltage
state does not exceed 1ms, the LVR will ignore it and
will not perform a reset function.
The LVR uses an OR function with the external RES
signal to perform a chip reset.
tion with a 4MHz system clock.
LVR
OPR
HT48R01/HT48R02/HT48R03
, such as when changing the battery, the LVR
is the voltage range for proper chip opera-
LVR
, therefore a t
LVR
DD
) has to remain in this con-
and V
LVR
December 20, 2006
LVR
is shown below.
delay enters