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Integrated Device Technology
|Description||3.3V EEPROM PROGRAMMABLE CLOCK GENERATOR|
|IDT5V9888 Datasheet PDF : 37 Pages |
3.3V EEPROM PROGRAMMABLE CLOCK GENERATOR
INDUSTRIAL TEMPERATURE RANGE
Understanding the GIN Signals
During power up, the part will virtually be in MFC mode2, therefore, the values of GIN3, GIN2, GIN1 and GIN0 will be latched and used for PLL configuration
selection, regardless of the state of the I2C/JTAG pin. GIN4 is not latched, and will assume the LOW state internally when in programming mode. This means
that when in programming mode, the PLL configuration can only be changed by writing directly to the registers of the currently selected configuration. When
in MFC mode 2, configuration 0 or 1 (GIN4=0) should be selected if you do not want to change configurations when entering or leaving programming mode.
The GIN pins should be held LOW during power up to select configuration0 as default.
When not in programming mode, the GIN inputs directly control the selected configuration. The internal GINx signals can be individually disabled via
programming the GINEN bits (0x06). When disabled by setting GINENx to "0", the GINx inputs may be left floating, but during power up, the GIN pins will still
latch. Disabled inputs are interpreted as LOW by the internal state machines. Even if disabled, GIN2, GIN1, GIN0 and GIN3 pins will be enabled if required
for I2C or JTAG programming functions when in programming mode. The CLK_SEL function on the GIN4 pin will be rendered completely non-functional when
SHUTDOWN/ENABLE OF OUTPUTS
The SHUTDOWN/OE pin, along with internal bits, controls the enabling/disabling of the output banks. The SHUTDOWN/OE pin can be programmed to function
as an output enable or global shutdown. The polarity of the SHUTDOWN/OE signal pin can be programmed to be either active HIGH or LOW with the SP bit
(0x1C). When SP is "0", the pin becomes active HIGH and when SP is "1", the pin becomes active LOW. The SH bit(0x1C) determines the function of the
SHUTDOWN/OE signal pin. If SH is "1", the signal pin is SHUTDOWN and functions as a global shutdown. This will override the OEx (0x1C), OSx (0x1D),
and PLLSx (0x1E) bits. If SH is "0", the signal pin is OE and functions as an enable/disable of the output banks. If used as an output enable/disable, each
output bank can be individually programmed to be enabled or disabled by the OE pin.by setting OEx bits to "1". If the OE signal pin is asserted, the output banks
that has their corresponding OEx bit set to "1" will be disabled. The OEMx bits determine the outputs' disable state. When set to "0x" the outputs will be tristated.
When set to "10", the outputs will be pulled low. When set to "11", the outputs will be pulled high. Inverted outputs will be parked in the opposite state. If the
OEx bits are set to "0", the states of the corresponding output banks will not be impacted by the state of the OE pin. To individually enable/disable via programming
instead of the OE pin, hard wire the OE pin to Vdd or GND (depending if it is active HIGH or LOW) as if to disable the outputs. Then toggle the OEx bits to either
"0" to enable or "1" to disable.
When the chip is in shutdown, the outputs, the reference oscillator, and the I2C /JTAG pin are powered down. The outputs will be tristated and the I2C
/JTAG pin will be set to MFC mode (MID level). Programming will not be allowed. The GINx pins and clock inputs remain operational. The PLL is not disabled.
The SHUTDOWN pin must be reasserted in order to program the part or to resume operation.
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