HT46R71D-1 Holtek Semiconductor, HT46R71D-1 Datasheet - Page 20

• Manufacturer Part Number: HT46R71D-1
• Description: Dual Slope A/D Type MCU
• Manufacturer: Holtek Semiconductor

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It is recommended that unused or not bonded out I/O
lines should be set as output pins using software in-
structions to avoid consuming power when in an input
state.
Charge Pump and Voltage Regulator
There is one charge pump and one voltage regulator im-
plement in this device.
The charge pump can be enabled/disabled by the appli-
cation program. The charge pump uses VDD as its in-
put, and has the function of doubling the V
The output voltage of the charge pump will be V
The regulator can generate a stable voltage of 3.3V, for
the ADC and also can provide an external bridge sensor
excitation voltage or supply a reference voltage for other
applications. The user needs to guarantee the charge
pump output voltage is greater than 3.6V to ensure that
the regulator generates the required 3.3V voltage out-
put. The block diagram of this module is shown below.
Rev. 1.00
DD
voltage.
Input/Output Ports
DD
2.
20
Additionally, the device also includes a band gap volt-
age generator for the 1.5V low temperature sensitive
reference voltage. This reference voltage is used as the
zero adjustment and for a single end type reference volt-
age.
R
Note: VOBGP signal is only for chip internal used.
There is a single register associated with this module
named CHPRC. The CHPRC is the Charge Pump/Reg-
ulator Control register, which controls the charge pump
on/off, regulator on/off functions as well as setting the
clock divider value to generate the clock for the charge
pump.
The CHPCKD4~CHPCKD0 bits are use to set the clock
divider to generate the desired clock frequency for
proper charge pump operation. The actual frequency is
determined by the following formula.
Actual Charge Pump Clock= (f
FIL
is about 100k and the recommend C
Don t connect to external component except the
recommend C
FIL
SYS
/16)/(CHPCKD +1).
HT46R71D-1
May 14, 2007
FIL
is 10 F.