32-bit ARM Cortex™-M3 MCU
HT32F1251/51B/52/53
External Clock Characteristics
Table 8. High Speed External Clock (HSE) Characteristics
TA = 25°C, unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
High Speed External oscillator
frequency (HSE)
fHSE
VDD33 = 3.3 V
4
—
16
MHz
Recommended load capacitance on
XTALIN and XTALOUT
CHSE
—
—
TBD
1.0
—
—
pF
Recommended external feedback
resistor between XTALIN and
XTALOUT
RFHSE
MΩ
DHSE
HSE Oscillator Duty cycle
40
—
—
—
—
0.96
—
60
—
0.1
4
%
IDDHSE
ISTBHSE
tSUHSE
HSE Oscillator Operating Current
HSE Oscillator Standby current
HSE Oscillator Startup time
VDD33 = 3.3 V, TA = 25°C
VDD33 = 3.3 V, TA = 25°C
VDD33 = 3.3 V, TA = 25°C
mA
μA
ms
—
Table 9. Low Speed External Clock (LSE) Characteristics
TA = 25°C, unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
Low Speed External oscillator
frequency (LSE)
=
fLSE
V
DD33 = VBAT 3.3 V
—
32.768
—
kHz
Recommended load capacitance on
XTAL32IN and XTAL32OUT
CLSE
—
—
TBD
—
pF
Recommended external feedback
resistor between XTAL32IN and
XTAL32OUT
RFLSE
DLSE
—
—
—
40
—
10
—
—
60
—
MΩ
%
LSE Oscillator Duty cycle
VDD33 = VBAT = 3.3 V,
LSESM = 0 (Normal
startup mode)
IDDLSE
LSE Oscillator Operating Current
1.7
μA
VDD33 = VBAT = 3.3 V,
LSESM = 1 (Fast startup
mode)
ISTBLSE
LSE Oscillator Standby current
LSE Oscillator Startup time
—
—
3
8
μA
VDD33 = VBAT = 3.3 V,
LSESM = 1 (Fast startup
mode)
tSULSE
200
—
ms
Rev. 1.00
24 of 35
May 27, 2011
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
