Catalyst CAT522 8-bit dual digital pot with independent reference input Datasheet

Advanced Information
CAT522
8-Bit Dual Digital POT With Independent Reference Inputs
FEATURES
APPLICATIONS
■ Buffered Outputs
■ Automated product calibration.
■ Output settings retained without power
■ Remote control adjustment of equipment
■ Independent Reference Inputs
■ Offset, gain and zero adjustments in Self-
Calibrating and Adaptive Control systems.
■ Output range includes both supply rails
■ Tamper-proof calibrations.
■ Programming voltage generated on-chip
■ 2 independently addressable outputs
■ Serial µP interface
■ Single supply operation: 2.7V-5.5V
DESCRIPTION
and stored settings can be read back without disturbing
the DAC’s output.
The CAT522 is a dual 8-Bit Memory DAC designed as an
electronic replacement for mechanical potentiometers
and trim pots. Intended for final calibration of products
such as camcorders, fax machines and cellular telephones on automated high volume production lines and
systems capable of self calibration, it is also well suited
for applications were equipment requiring periodic adjustment is either difficult to access or located in a
hazardous environment.
Control of the CAT522 is accomplished with a simple 3
wire serial interface. A Chip Select pin allows several
CAT522's to share a common serial interface and communications back to the host controller is via a single
serial data line thanks to the CAT522’s Tri-Stated Data
Output pin. A RDY/BSY output working in concert with
an internal low voltage detector signals proper operation
of EEPROM Erase/Write cycle.
The CAT522 offers 2 independently programmable DACs
each having its own reference inputs and each capable
of rail to rail output swing. Outputs are buffered by rail
to rail OP AMPS Output settings, stored in non-volatile
EEPROM memory, are not lost when the device is
powered down and are automatically reinstated when
power is returned. Each output can be dithered to test
new output values without effecting the stored settings
The CAT522 operates from a single 3–5 volt power
supply. The high voltage required for EEPROM Erase/
Write operations is generated on-chip.
FUNCTIONAL DIAGRAM
PIN CONFIGURATION
The CAT522 is available in the 0°C to 70°C Commercial
and –40°C to +85°C Industrial operating temperature
ranges and offered in 14-pin plastic DIP and Surface
mount packages.
VDD
DIP Package (P)
1
RDY/BSY
PROG
3
7
6
SERIAL DATA OUTPUT
DO
PROGRAM
CONTROL
14
V
REF
H1
VDD
1
14
VREF H1
CLK
2
13
VREF H2
RDY/BSY
3
12
CS
4
11
CAT522
5
10
VREF L2
DI
EEPROM
LATCH
DAC 1
+
12
–
9
CLK
CS
2
4
DI
1
V
OUT
V REF L1
DATA
CONTROLLER
DI
13
5
EEPROM
DAC 2
LATCH
+
11
–
10
V
H2
REF
V
2
OUT
VREF L2
H.V.
CHARGE
PUMP
CAT522
8
GND
© 2000 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
SOIC Package (J)
1
VDD
1
14
VREF H1
CLK
2
13
VREF H2
VOUT1
RDY/BSY
3
12
VOUT1
VOUT2
CS
4
11
CAT522
5
10
VOUT2
VREF L2
DO
6
9
VREF L1
PROG
7
8
GND
DO
6
9
VREF L1
PROG
7
8
GND
CAT522
Advanced Information
Operating Ambient Temperature
Commercial (‘C’ suffix) .................... 0°C to +70°C
Industrial (‘I’ suffix) ...................... – 40°C to +85°C
Junction Temperature ..................................... +150°C
Storage Temperature ....................... –65°C to +150°C
Lead Soldering (10 sec max) .......................... +300°C
ABSOLUTE MAXIMUM RATINGS
Supply Voltage*
VDD to GND ...................................... –0.5V to +7V
Inputs
CLK to GND ............................ –0.5V to VDD +0.5V
CS to GND .............................. –0.5V to VDD +0.5V
DI to GND ............................... –0.5V to VDD +0.5V
RDY/BSY to GND ................... –0.5V to VDD +0.5V
PROG to GND ........................ –0.5V to VDD +0.5V
VREFH to GND ........................ –0.5V to VDD +0.5V
VREFL to GND ......................... –0.5V to VDD +0.5V
Outputs
D0 to GND ............................... –0.5V to VDD +0.5V
VOUT 1– 2 to GND ................... –0.5V to VDD +0.5V
* Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Absolute
Maximum Ratings are limited values applied individually while
other parameters are within specified operating conditions,
and functional operation at any of these conditions is NOT
implied. Device performance and reliability may be impaired by
exposure to absolute rating conditions for extended periods of
time.
RELIABILITY CHARACTERISTICS
Symbol
Parameter
Min
VZAP(1)
ILTH(1)(2)
ESD Susceptibility
Latch-Up
2000
100
Max
Units
Test Method
Volts
mA
MIL-STD-883, Test Method 3015
JEDEC Standard 17
NOTES: 1. This parameter is tested initially and after a design or process change that affects the parameter.
2. Latch-up protection is provided for stresses up to 100mA on address and data pins from –1V to VCC + 1V.
DC ELECTRICAL CHARACTERISTICS: VDD = +2.7V to +5.5V, VREFH = VDD, VREFL = 0V, unless otherwise specified
Symbol
Parameter
Conditions
Resolution
Min
Typ
Max
Units
8
—
—
Bits
—
—
—
—
—
—
—
—
0.6
0.6
1.2
1.2
0.25
0.25
0.5
0.5
±1
±1
—
—
± 0.5
± 0.5
—
—
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
—
—
2
0
—
—
—
—
10
–10
VDD
0.8
µA
µA
V
V
2.7
GND
—
—
—
28K
VDD
VDD -2.7
—
V
V
Ω
—
± 0.5
±1
%
VDD –0.3
—
—
—
—
—
—
0.4
0.4
V
V
V
Accuracy
INL
Integral Linearity Error
ILOAD = 10 µA,
ILOAD = 40 µA,
DNL
Differential Linearity Error
ILOAD = 10 µA,
ILOAD = 40 µA,
TR = C
TR = I
TR = C
TR = I
TR = C
TR = I
TR = C
TR = I
Logic Inputs
IIH
IIL
VIH
VIL
Input Leakage Current
Input Leakage Current
High Level Input Voltage
Low Level Input Voltage
VIN = VDD
VIN = 0V
References
VRH
VRL
ZIN
VREFH Input Voltage Range
VREFL Input Voltage Range
VREFH–VREFL Resistance
∆VIN / RIN
Input Resistance Match
Logic Outputs
VOH
VOL
8/00
High Level Output Voltage
Low Level Output Voltage
IOH = – 40 µA
IOL = 1 mA, VDD = +5V
IOL = 0.4 mA, VDD = +3V
2
CAT522
Advanced Information
DC ELECTRICAL CHARACTERISTICS (Cont.):
VDD = +2.7V to +5.5V, VREFH = VDD, VREFL = 0V, unless otherwise specified
Symbol
Parameter
Conditions
Min
Typ
Max
Units
0.99 VR
—
—
—
—
—
0.995 VR
0.005 VR
—
—
—
—
—
0.01 VR
1
1K
1K
1
V
V
µA
Ω
Ω
LSB / V
VDD = +5V, ILOAD = 250nA
VREFH= +5V, VREFL = 0V
VREFH to VREFL
—
—
200
µV/ °C
—
700
—
ppm / °C
Normal Operating
Programming, VDD = 5V
VDD = 3V
—
—
—
2.7
0.4
1.6
1.0
—
0.6
2.5
1.6
5.5
mA
mA
mA
V
Min
Typ
Max
Units
150
100
0
50
50
—
—
—
—
—
150
700
500
300
DC
—
—
—
—
—
—
—
400
400
4
—
—
—
—
—
—
—
—
—
—
150
150
—
—
5
—
—
—
—
1
ns
ns
ns
ns
ns
ns
ns
ns
ns
ms
ns
ns
ns
ns
MHz
CLOAD = 10 pF, VDD = +5V
CLOAD = 10 pF, VDD = +3V
—
—
3
6
10
10
µs
µs
VIN = 0V, f = 1 MHz(2)
VOUT = 0V, f = 1 MHz(2)
—
—
8
6
—
—
pF
pF
Analog Output
FSO
ZSO
IL
ROUT
Full-Scale Output Voltage
Zero-Scale Output Voltage
DAC Output Load Current
DAC Output Impedance
PSSR
Power Supply Rejection
VR = VREFH – VREFL
VR = VREFH – VREFL
VDD = VREFH = +5V
VDD = VREFH = +3V
ILOAD = 1 µA
Temperature
TCO
VOUT Temperature Coefficient
TCREF
Temperature Coefficient of
VREF Resistance
Power Supply
IDD1
IDD2
Supply Current (Read)
Supply Current (Write)
VDD
Operating Voltage Range
AC ELECTRICAL CHARACTERISTICS:
VDD = +2.7V to +5.5V, VREFH = VDD, VREFL = 0V, unless otherwise specified
Symbol
Parameter
Conditions
Digital
tCSMIN
tCSS
tCSH
tDIS
tDIH
tDO1
tDO0
tHZ
tLZ
tBUSY
tPS
tPROG
tCLKH
tCLKL
fC
Minimum CS Low Time
CS Setup Time
CS Hold Time
DI Setup Time
DI Hold Time
Output Delay to 1
Output Delay to 0
Output Delay to High-Z
Output Delay to Low-Z
Erase/Write Cycle Time
PROG Setup Time
Minimum Pulse Width
Minimum CLK High Time
Minimum CLK Low Time
Clock Frequency
CL = 100 pF,
see note 1
Analog
tDS
DAC Settling Time to 1 LSB
Pin Capacitance
CIN
COUT
Input Capacitance
Output Capacitance
NOTES: 1. All timing measurements are defined at the point of signal crossing VDD / 2.
2. These parameters are periodically sampled and are not 100% tested.
3
8/00
CAT522
Advanced Information
A. C. TIMING DIAGRAM
to
1
2
3
4
5
t CLK H
CLK
t CSS
t CLK L
t CSH
CS
t CSMIN
t DIS
DI
t DIH
t DO0
t LZ
DO
t HZ
t DO1
PROG
t PS
t PROG
RDY/BSY
t BUSY
to
8/00
1
2
3
4
4
5
CAT522
Advanced Information
PIN DESCRIPTION
Pin
DAC addressing is as follows:
Name
Function
1
2
3
4
5
6
7
VDD
CLK
RDY/BSY
CS
DI
DO
PROG
8
9
10
11
12
13
14
GND
VREFL1
VREFL2
VOUT2
VOUT1
VREFH2
VREFH1
Power supply positive
Clock input pin
Ready/Busy output
Chip select
Serial data input pin
Serial data output pin
EEPROM Programming Enable
Input
Power supply ground
Minimum DAC 1 output voltage
Minimum DAC 2 output voltage
DAC 2 output
DAC 1 output
Maximum DAC 2 output voltage
Maximum DAC 1 output voltage
DAC OUTPUT
A0
A1
VOUT1
0
1
VOUT2
1
1
DEVICE OPERATION
CHIP SELECT
The CAT522 is a dual 8-bit Digital to Analog Converter
(DAC) whose outputs can be programmed to any one of
256 individual voltage steps. Once programmed, these
output settings are retained in non-volatile EEPROM
memory and will not be lost when power is removed from
the chip. Upon power up the DACs return to the settings
stored in EEPROM memory. Each DAC can be written
to and read from independently without effecting the
output voltage during the read or write cycle. Each
output can also be adjusted without altering the stored
output setting, which is useful for testing new output
settings before storing them in memory.
Chip Select (CS) enables and disables the CAT522’s
read and write operations. When CS is high data may be
read to or from the chip, and the Data Output (DO) pin is
active. Data loaded into the DAC control registers will
remain in effect until CS goes low. Bringing CS to a logic
low returns all DAC outputs to the settings stored in
EEPROM memory and switches DO to its high impedance Tri-State mode.
Because CS functions like a reset the CS pin has been
desensitized with a 30 ns to 90 ns filter circuit to prevent
noise spikes from causing unwanted resets and the loss
of volatile data.
DIGITAL INTERFACE
CLOCK
The CAT522 employs a standard 3 wire serial control
interface consisting of Clock (CLK), Chip Select (CS)
and Data In (DI) inputs. For all operations, address and
data are shifted in LSB first. In addition, all digital data
must be preceded by a logic “1” as a start bit. The DAC
address and data are clocked into the DI pin on the
clock’s rising edge. When sending multiple blocks of
information a minimum of two clock cycles is required
between the last block sent and the next start bit.
The CAT522’s clock controls both data flow in and out of
the IC and EEPROM memory cell programming. Serial
data is shifted into the DI pin and out of the DO pin on the
clock’s rising edge. While it is not necessary for the clock
to be running between data transfers, the clock must be
operating in order to write to EEPROM memory, even
though the data being saved may already be resident in
the DAC control register.
No clock is necessary upon system power-up. The
CAT522’s internal power-on reset circuitry loads data
from EEPROM to the DACs without using the external
clock.
Multiple devices may share a common input data line by
selectively activating the CS control of the desired IC.
Data Outputs (DO) can also share a common line
because the DO pin is Tri-Stated and returns to a high
impedance when not in use.
5
8/00
CAT522
Advanced Information
As data transfers are edge triggered clean clock transitions are necessary to avoid falsely clocking data into the
control registers. Standard CMOS and TTL logic families work well in this regard and it is recommended that
any mechanical switches used for breadboarding or
device evaluation purposes be debounced by a flip-flop
or other suitable debouncing circuit.
its high impedance Tri-State mode when CS returns low.
Tri-Stating the DO pin allows several 522s to share a
single serial data line and simplifies interfacing multiple
522s to a microprocessor.
WRITING TO MEMORY
Programming the CAT522’s EEPROM memory is accomplished through the control signals: Chip Select
(CS) and Program (PROG). With CS high, a start bit
followed by a two bit DAC address and eight data bits are
clocked into the DAC control register via the DI pin. Data
enters on the clock’s rising edge. The DAC output
changes to its new setting on the clock cycle following
D7, the last data bit.
VREF
VREF, the voltage applied between pins VREFH &VREFL,
sets the DAC’s Zero to Full Scale output range where
VREFL = Zero and VREFH = Full Scale. VREF can span the
full power supply range or just a fraction of it. In typical
applications VREFH &VREFL are connected across the
power supply rails. When using less than the full supply
voltage be mindfull of the limits placed on VREFH and
VREFL as specified in the References section of DC
Electrical Characteristics.
Programming is accomplished by bringing PROG high
sometime after the start bit and at least 150 ns prior to the
rising edge of the clock cycle immediately following the
D7 bit. Two clock cycles after the D7 bit the DAC control
register will be ready to receive the next set of address
and data bits. The clock must be kept running throughout the programming cycle. Internal control circuitry
takes care of generating and ramping up the programming voltage for data transfer to the EEPROM cells. The
CAT522’s EEPROM memory cells will endure over
1,000,000 write cycles and will retain data for a minimum
of 100 years without being refreshed.
BUSY
READY/BUSY
When saving data to non-volatile EEPROM memory, the
Ready/Busy ouput (RDY/BSY) signals the start and
duration of the EEPROM erase/write cycle. Upon receiving a command to store data (PROG goes high) RDY/
BSY goes low and remains low until the programming
cycle is complete. During this time the CAT522 will
ignore any data appearing at DI and no data will be
output on DO.
READING DATA
Data is output serially by the CAT522, LSB first, via the
Data Out (DO) pin following the reception of a start bit
and two address bits by the Data Input (DI). DO
becomes active whenever CS goes high and resumes
Each time data is transferred into a DAC control register
currently held data is shifted out via the D0 pin, thus in
every data transaction a read cycle occurs. Note,
however, that the reading process is destructive. Data
must be removed from the register in order to be read.
Figure 2 depicts a Read Only cycle in which no change
occurs in the DAC’s output. This feature allows µPs to
poll DACs for their current setting without disturbing the
output voltage but it assumes that the setting being read
is also stored in EEPROM so that it can be restored at the
end of the read cycle. In Figure 2 CS returns low before
the 13th clock cycle completes. In doing so the EEPROM’s
Figure 1. Writing to Memory
Figure 2. Reading from Memory
RDY/BSY is internally ANDed with a low voltage detector circuit monitoring VDD. If VDD is below the minimum
value required for EEPROM programming, RDY/BSY
will remain high following the program command indicating a failure to record the desired data in non-volatile
memory.
DATA OUTPUT
to
1
2
3
4
5
6
7
8
9
10
11
12
N
N+1 N+2
to
1
2
3
4
5
6
7
8
9
10
11
12
CS
CS
NEW DAC DATA
DI
1
A0
A1
D0
D1
D2
D3
D4
D5
D6
D7
DI
D6
D7
DO
1
A0
A1
CURRENT DAC DATA
DO
D0
D1
D2
D3
D4
D5
CURRENT DAC DATA
PROG
PROG
RDY/BSY
RDY/BSY
DAC
OUTPUT
8/00
CURRENT
DAC VALUE
NON-VOLATILE
NEW
DAC VALUE
NEW
DAC VALUE
VOLATILE
NON-VOLATILE
DAC
OUTPUT
6
D0
D1
D2
D3
D4
D5
CURRENT
DAC VALUE
NON-VOLATILE
D6
D7
CAT522
Advanced Information
Figure 3. Temporary Change in Output
setting is reloaded into the DAC control register. Since
this value is the same as that which had been there
previously no change in the DAC’s output is noticed.
Had the value held in the control register been different
from that stored in EEPROM then a change would occur
at the read cycle’s conclusion.
to
1
2
3
4
5
6
7
8
9
10
11
12
N
N+1 N+2
CS
NEW DAC DATA
TEMPORARILY CHANGE OUTPUT
1
DI
A0
A1
D0
D1
D0
D1
D2
D3
D4
D5
D6
D7
D6
D7
CURRENT DAC DATA
The CAT522 allows temporary changes in DAC’s output
to be made without disturbing the settings retained in
EEPROM memory. This feature is particularly useful
when testing for a new output setting and allows for user
adjustment of preset or default values without losing the
original factory settings.
DO
D2
D3
D4
D5
PROG
RDY/BSY
DAC
OUTPUT
Figure 3 shows the control and data signals needed to
effect a temporary output change. DAC settings may be
changed as many times as required and can be made to
any of the two DACs in any order or sequence. The
temporary setting(s) remain in effect long as CS remains
high. When CS returns low all two DACs will return to the
output values stored in EEPROM memory.
CURRENT
DAC VALUE
NON-VOLATILE
NEW
DAC VALUE
VOLATILE
CURRENT
DAC VALUE
NON-VOLATILE
When it is desired to save a new setting acquired using
this feature, the new value must be reloaded into the
DAC control register prior to programming. This is because the CAT522’s internal control circuitry discards
from the programming register the new data two clock
cycles after receiving it if no PROG signal is received.
APPLICATION CIRCUITS
+5V
DAC INPUT
Vi
RI
DAC OUTPUT
RF
CODE (V - V
VDAC = ———
FS ZERO ) + VZERO
255
+15V
VDD
CONTROL
& DATA
VREF H
GND
VFS = 0.99 VREF
V OUT
–
+
OPT
505
CAT522
OP 07
MSB
LSB
VZERO = 0.01 VREF
VREF = 5V
R I = RF
1111
1111
255 (.98 V
——
REF ) + .01 VREF = .990 VREF
255
VOUT = +4.90V
1000
0000
V
= +0.02V
OUT
0111
1111
0000
0001
128 (.98 V
——
) + .01 V
= .502 V
REF
REF
REF
255
127
—— (.98 V
) + .01 V
= .498 V
255
REF
REF
REF
1 (.98 V
——
) + .01 V
= .014 V
255
REF
REF
REF
0000
0000
0 (.98 V
——
) + .01 V
= .010 V
REF
REF
REF
255
V
= -4.90V
OUT
-15V
VREF L
ANALOG
OUTPUT
VOUT = VDAC ( R I+ RF) -VI R F
RI
For R I = RF
VOUT = 2VDAC -VI
V
= -0.02V
OUT
V
= -4.86V
OUT
Bipolar DAC Output
+5V
RI
RF
+15V
VDD
CONTROL
& DATA
VREF H
–
+
OPT 505
CAT522
GND
VOUT
OP 07
-15V
VREF L
RF
VOUT = (1 + –––)
V DAC
RI
Amplified DAC Output
7
8/00
CAT522
Advanced Information
APPLICATION CIRCUITS (Cont.)
+5V
VREF
RC = —————
256 * 1 µA
+5V
VDD
VREF
VDD
Fine adjust gives ± 1 LSB change in V OFFSET
VREF
when VOFFSET = ———
2
VREFH
+VREF
VREFH
127RC
FINE ADJUST
DAC
+
(+VREF ) - (VOFFSET )
RC = ———————————
1 µA
127RC
FINE ADJUST
DAC
(-VREF ) + (VOFFSET+ )
Ro = ———————————
1 µA
+V
COARSE ADJUST
DAC
RC
V OFFSET
+
GND
VREF L
+V
Ro
–
GND
RC
COARSE ADJUST
DAC
VOFFSET
-VREF
VREF L
+
–
-V
Coarse-Fine Offset Control by Averaging DAC Outputs
for Single Power Supply Systems
Coarse-Fine Offset Control by Averaging DAC Outputs
for Dual Power Supply Systems
28 - 32V
V+
I > 2 mA
15K
10 µF
VDD
VREF H
1N5231B
VREF = 5.000V
VDD
CONTROL
& DATA
OPT
505
CAT522
GND
VREF H
5.1V
10K
LT 1029
CONTROL
& DATA
VREF L
OPT 505
CAT522
GND
VREF L
+
–
MPT3055EL
LM 324
OUTPUT
4.02 K
1.00K
Digitally Trimmed Voltage Reference
8/00
Digitally Controlled Voltage Reference
8
10 µF
35V
0 - 25V
@ 1A
CAT522
Advanced Information
APPLICATION CIRCUITS (Cont.)
+5V
2.2K
VDD
VREF
4.7 µA
LM385-2.5
ISINK = 2 - 255 mA
+15V
DAC
+
+5V
CONTROL
& DATA
10K
CAT522
OPT 505
1 mA steps
2N7000
–
10K
39Ω1W
39Ω 1W
DAC
+
5 µA steps
2N7000
–
VREF L
GND
5 meg
5 meg
3.9K
10K
10K
–
TIP 30
+
-15V
Current Sink with 4 Decades of Resolution
+15V
51K
+
TIP 29
–
10K
10K
+5V
VDD
VREF H
5 meg
5 meg
39Ω 1W
DAC
39Ω 1W
CONTROL
& DATA
–
OPT 505
CAT522
5 meg
DAC
GND
BS170P
+
5 meg
1 mA steps
3.9K
–
VREF L
BS170P
5 µA steps
+
LM385-2.5
-15V
ISOURCE = 2 - 255 mA
Current Source with 4 Decades of Resolution
9
8/00
CAT522
Advanced Information
ORDERING INFORMATION
Prefix
Device #
Suffix
CAT
522
J
Optional
Company ID
Product
Number
Package
P: PDIP
J: SOIC
I
2000/Reel
Temperature Range
Blank = Commercial (0˚C to +70˚C)
I = Industrial (-40˚C to +85˚C)
Notes:
(1) The device used in the above example is a CAT522JI-TE13 (SOIC, Industrial Temperature, Tape & Reel)
8/00
10
-TE13
Tape & Reel
TE13:
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