F75909
1 General Description
The F75909 is a I2C-bus/SMBus level shifter that translating signal voltage level of standard I2C-bus or
SMBus. Port L allows a operating voltage range from 1.0 V to [VCC(H) -1.0 V]. The operating voltage of Port
H is range from 3.0 V to 5.5 V. When F75909 is disabled, both port L and port H I/O pins are high-
impedance.
The bus port H are compliant with SMBus I/O levels, while port L uses a current sensing mechanism to
detect the input or output LOW signal which prevents bus lock-up. Port L uses a 1 mA current source for
pull-
pull-down driver. This results in a LOW on the port L accommodating smaller voltage
swings. The output pull-down on the port L internal buffer LOW is set for approximately 0.2 V, while the
input threshold of the internal buffer is set about 50 mV lower than that of the output voltage LOW. When
the port L I/O is driven LOW internally, the LOW is not recognized as a LOW by the input. This prevents a
lock-up condition from occurring. The output pull-down on the port H drives a hard LOW and the input level
is set at 0.3 of SMBus or I2C-bus voltage level which enables port H to connect to any other I2C-bus devices
or buffer.
The F75909 is not enabled unless VCC(L) is above 0.8 V and VCC(H) is above 2.5 V. The enable (EN) pin
can also be used to turn the drivers on and off under system control. Caution should be observed to only
change the state of the EN pin when the bus is idle.
2 Feature List
Voltage level shifting from L-Port (1V to Vcc(H) -1.0V)
No external pull-up resistors required on Port L
Open-drain I/O
Lock-up free operation
High impedance bus pin when Power-off.
Dec, 2011
V0.12P
1
FINTEK [ FEATURE INTEGRATION TECHNOLOGY INC. ]
