sh66p31b SinoWealth Micro-Electronics Corp. Ltd, sh66p31b Datasheet - Page 16

• Manufacturer Part Number: sh66p31b
• Description: Otp 1k 4-bit Micro-controller
• Manufacturer: SinoWealth Micro-Electronics Corp. Ltd

10. Low Power Detection (LPD)
The LPD function monitors the supply voltage and applies an internal reset in the micro-controller at battery replacement. If the
applied circuit satisfies the following conditions, the LPD can be incorporated by the software control.
The software enable flag controls LPD circuit on/off.
LPD circuit Operating ambient temperature is T
Functions of LPD Circuit:
The LPD circuit has the following functions:
Generates an internal reset signal when V
Cancels the internal reset signal when V
Stops the oscillator operation and force the CPU to enter STOP mode when V
As V
then cancel the LPD reset.
LPD Control Register:
11. HALT and STOP Mode
After the execution of HALT instruction, SH66P31B will enter HALT mode. In HALT mode, the CPU will stop operating; but the
peripheral circuit (timer) will keep operating.
After the execution of STOP instruction, SH66P31B will enter STOP mode.
In STOP mode, the entire chip (including oscillator) will stop operating.
In HALT mode, SH66P31B can be waked up if any interrupt occurs.
In STOP mode, SH66P31B can be waked up if port interrupt occurs.
12. Warm-up Timer
The device has a built-in warm-up timer to eliminate unstable state of initial oscillation when oscillator starts oscillating in the
following conditions
Power-on Reset
Wake up from Stop Mode
Warm-up time interval:
(1) In Crystal oscillator or Ceramic resonator mode, f
(2) In Crystal oscillator or Ceramic resonator mode, f
13. Code Option
Port Interrupt Source Select:
0: Int. source: PB, PC (Default)
1: Int. source: PA.1 - 3, PB.0 - 3, PC.0
Instruction Cycle Time:
0: Instruction cycle time = 4/f
1: Instruction cycle time = 16/f
LPD Function Enable Select:
0: Use LPD register ($15) control (Default = 0)
1: LPD always enable, LPD register ($15) inactive.
Address
$15
DD
≤
V
LPD
LPD3
, the LPD reset will delay about 1.2ms before being triggered. If V
Bit3
LPD2
Bit2
OSC
OSC
(Default) - (only use for less than 500kHz oscillator)
LPD1
Bit1
DD
DD
> V
≤ V
LPD
A
LPD0
LPD
Bit0
= -20 ℃ to + 70 ℃
.
.
OSC
OSC
= 455kHz, the warm-up time interval is 9 ms.
= 4MHz, the warm-up time interval is 1.02 ms
R/W
W
16
LPD Enable Control (LPD3 - 0):
When LPD function enable code option = 0
0101: LPD Enable (Power-on initial)
1010: LPD Disable
When LPD function enable code option = 1
xxxx: LPD Enable
DD
DD
≤ V
goes back to V
LPD
.
Remarks
DD
＞ V
LPD
SH66P31B
, without any delay