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INDUSTRIAL TEMPERATURE RANGE
IDT5T9890
EEPROM PROGRAMMABLE 2.5V PROGRAMMABLE SKEW PLL CLOCK DRIVER
The following sections provide a brief description of each instruction. For a
complete description refer to the IEEE Standard Test Access Port Specification
(IEEE Std. 1149.1-1990).
EXTEST
The required EXTEST instruction places the IC into an external boundary-
test mode and selects the boundary-scan register to be connected between
TDI and TDO. During this instruction, the boundary-scan register is accessed
to drive test data off-chip through the boundary outputs, and recieve test data
off-chip through the boundary inputs. As such, the EXTEST instruction is the
workhorse of IEEE. Std 1149.1, providing for probe-less testing of solder-joint
opens/shorts and of logic cluster function.
SAMPLE/PRELOAD
The required SAMPLE/PRELOAD instruction allows the IC to remain in a
normal functional mode and selects the boundary-scan register to be connected
between TDI and TDO. During this instruction, the boundary-scan register can
be accessed via a data scan operation, to take a sample of the functional data
entering and leaving the IC.
IDCODE
The optional IDCODE instruction allows the IC to remain in its functional mode
and selects the optional device identification register to be connected between
TDI and TDO. The device identification register is a 32-bit shift register
containing information regarding the IC manufacturer, device type, and
version code. Accessing the device identification register does not interfere
with the operation of the IC. Also, access to the device identification register
should be immediately available, via a TAP data-scan operation, after power-
up of the IC or after the TAP has been reset using the optional TRST pin or
by otherwise moving to the Test-Logic-Reset state.
PROGWRITE
The PROGWRITE instruction is for writing the IDT5T9890 configuration
data to the device’s volatile programming registers. This instruction selects the
programming register path for shifting data from TDI to TDO during data register
scanning. The programming register path has 112 registers (14 bytes)
between TDI and TDO. The 12 configuration data bytes are scanned in
through TDI first, starting with Bit 0. After scanning in the last configuration bit,
Bit 95, sixteen additional bits must be scanned in to place the configuration data
in the proper location. The last sixteen registers in the programming path are
reserved, read-only registers.
PROGREAD
The PROGREAD instruction is for reading out the IDT5T9890 configuration
data from the device’s volatile programming registers. This instruction selects
the programming register path for shifting data from TDI to TDO during data
register scanning. The programming register path has 112 registers between
TDI and TDO, and the first bit scanned out through TDO will be Bit 0 of the
configuration data.
PROGSAVE and PROGRESTORE (EEPROM OPERATION)
The PROGSAVE instruction is for copying the IDT5T9890 configuration
data from the device’s volatile programming registers to the EEPROM. This
instruction selects the BYPASS register path for shifting data from TDI to TDO
during data register scanning.
The PROGRESTORE instruction is for loading the IDT5T9890 configuration
data from the EEPROM to the device’s volatile programming registers. This
instruction selects the BYPASS register path for shifting data from TDI to TDO
during data register scanning.
During the execution of a PROGSAVE or PROGRESTORE instruction, the
IDT5T9890 will not accept a new programming instruction (read, write, save,
or restore). All non-programming JTAG instructions will function properly, but
the user should wait until the save or restore is complete before issuing a new
programming instruction. The time it takes for the save and restore instructions
to complete depends on the PLL oscillator frequency, FVCO. The restore time,
TRESTORE, and the save time, TSAVE, can be calculated as follows:
TRESTORE
= 1.23X10
9
/FVCO
(mS)
TSAVE
= 3.09X10
9
/
FVCO
+ 52 (mS)
If a new programming instruction is issued before the save or restore
completes, the new instruction is ignored, and the BYPASS register path
remains in effect for shifting data from TDI to TDO during data register scanning.
In order for the ProgSave and ProgRestore instructions to function properly,
the IDT5T9890 must not be in power-down mode (PD must be HIGH), and
the PLL must be enabled (PLL_EN = LOW and Bit 57 = 0).
On power-up of the IDT5T9890, an automatic restore is performed to load
the EEPROM contents into the internal programming registers. The auto-
restore will not function properly if the device is in power-down mode (PD must
be HIGH). The device's auto-restore feature will function regardless of the state
of the PLL_EN pin or Bit 57. The time it takes for the device to complete the
auto-restore is approximately 3ms.
CLAMP
The optional CLAMP instruction loads the contents from the boundary-scan
register onto the outputs of the IC, and selects the one-bit bypass register to
be connected between TDI and TDO. During this instruction, data can be
shifted through the bypass register from TDI to TDO without affecting the
condition of the IC outputs.
HIGH-IMPEDANCE
The optional High-Impedance instruction sets all outputs (including two-state
as well as three-state types) of an IC to a disabled (high-impedance) state and
selects the one-bit bypass register to be connected between TDI and TDO.
During this instruction, data can be shifted through the bypass register from TDI
to TDO without affecting the condition of the IC outputs.
BYPASS
The required BYPASS instruction allows the IC to remain in a normal
functional mode and selects the one-bit bypass register to be connected
between TDI and TDO. The BYPASS instruction allows serial data to be
transferred through the IC from TDI to TDO without affecting the operation of
the IC.
