HT46R74D-1 Holtek Semiconductor, HT46R74D-1 Datasheet - Page 22

• Manufacturer Part Number: HT46R74D-1
• Description: Dual Slope A/D Type MCU
• Manufacturer: Holtek Semiconductor

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Charge Pump and Voltage Regulator
A charge pump and voltage regulator are integrated
within the device. The charge pump can be enabled/dis-
abled by the application program. The charge pump
uses VDD as its input, and has the function of doubling
the V
age will be V
voltage of 3.3V for the ADC and also can provide an ex-
ternal bridge sensor excitation voltage or supply a refer-
ence voltage for other applications. The user needs to
ensure that the charge pump output voltage is greater
than 3.6V to ensure that the regulator is capable of gen-
erating the required 3.3V voltage output.
Rev. 1.10
DD
voltage, therefore the charge pump output volt-
DD
2. The regulator can generate a stable
Input/Output Ports
22
Additionally, the device also includes a band gap voltage
generator for the 1.5V low temperature sensitive refer-
ence voltage. This reference voltage is used as the zero
adjustment and for a single end type reference voltage.
R
is 10 F.
Note: The VOBGP signal is an internal signal only and
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 function, the 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 used 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
only the recommend C
and the recommend value for C
FIL
SYS
should be connected.
/16)/(CHPCKD +1).
HT46R74D-1
January 11, 2007
FIL