X9530 Datasheet, PDF (4/30 Pages) Xicor Inc. – Temperature Compensated Laser Diode Controller

X9530
PRINCIPLES OF OPERATION
CONTROL AND STATUS REGISTERS
The Control and Status Registers provide the user with
a mechanism for changing and reading the value of
various parameters of the X9530. The X9530 contains
seven Control, one Status, and several Reserved
registers, each being one Byte wide (See Figure 1).
The Control registers 0 through 6 are located at
memory addresses 80h through 86h respectively. The
Status register is at memory address 87h, and the
Reserved registers at memory address 88h through
8Fh.
All bits in Control register 6 always power up to the
logic state “0”. All bits in Control registers 0 through 5
power up to the logic state value kept in their
corresponding nonvolatile memory cells. The
nonvolatile bits of a register retain their stored values
even when the X9530 is powered down, then powered
back up. The nonvolatile bits in Control 0 through
Control 5 registers are all preprogrammed to the logic
state “0” at the factory.
Bits indicated as “Reserved” are ignored when read,
and must be written as “0”, if any Write operation is
performed to their registers.
A detailed description of the function of each of the
Control and Status register bits follows:
Control Register 0
This register is accessed by performing a Read or
Write operation to address 80h of memory.
BL1, BL0: BLOCK LOCK PROTECTION BITS (NON-VOLATILE)
These two bits are used to inhibit any write operation to
certain addresses within the memory array. The
protected region of memory is determined by the
values of the two bits as shown in the table below:
Protected Addresses Partition of array
(Size)
locked
00
None (Default)
None (Default)
0 1 00h to 7Fh (128 bytes)
GPM
1 0 00h to 7Fh and 90h to
CFh (192 bytes)
GPM, LUT1
1 1 00h to 7Fh and 90h to GPM, LUT1, LUT2
10Fh (256 bytes)
Notice that if the Write Protect (WP) input pin of the
X9530 is active (LOW), then any write operation to the
memory is inhibited, irrespective of the Block Lock bit
settings.
VRM: VOLTAGE REFERENCE PIN MODE (NON-VOLATILE)
The VRM bit configures the Voltage Reference pin
(VRef) as either an input or an output. When the VRM
bit is set to “0” (default), the voltage at pin VRef is an
output from the X9530’s internal voltage reference.
When the VRM bit is set to “1”, the voltage reference
for the VRef pin is external. See Figure 2.
ADCIN: A/D CONVERTER INPUT SELECT (NON-VOLATILE)
The ADCIN bit selects the input of the on-chip A/D
converter. When the ADCIN bit is set to “0” (default),
the output of the on-chip temperature sensor is the
input to the A/D converter. When the ADCIN bit is set
to “1”, the input to the A/D converter is the voltage at
the VSense pin. See Figure 4.
ADCFILTOFF: ADC FILTERING CONTROL (NON-VOLATILE)
When this bit is“1”, the status register at 87h is updated
after every conversion of the ADC. When this bit is “0”
(default), the status register is updated after four
consecutive conversions with the same result.
NV1234: CONTROL REGISTERS 1, 2, 3, AND 4 VOLATILITY MODE
SELECTION BIT (NON-VOLATILE)
When the NV1234 bit is set to “0” (default), bytes
written to Control registers 1, 2, 3, and 4 are stored in
volatile cells, and their content is lost when the X9530
is powered down. When the NV1234 bit is set to “1”,
bytes written to Control registers 1, 2, 3, and 4 are
stored in both volatile and nonvolatile cells, and their
value doesn’t change when the X9530 is powered
down and powered back up. See “Writing to Control
Registers” on page 17.
I1DS: CURRENT GENERATOR 1 DIRECTION SELECT BIT
(NON-VOLATILE)
The I1DS bit sets the polarity of Current Generator 1,
DAC1. When this bit is set to “0” (default), the Current
Generator 1 of the X9530 is configured as a Current
Source. Current Generator 1 is configured as a Current
Sink when the I1DS bit is set to “1”. See Figure 5.
If the user attempts to perform a write operation to a
protected region of memory, the operation is aborted
without changing any data in the array.
REV 3.7 8/26/04
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Characteristics subject to change without notice. 4 of 30