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Advanced Information
CAT521
8-Bit Digital POT With Independent Reference Inputs FEATURES
s Buffered Outputs s Output settings retained without power s Output range includes both supply rails s Programming voltage generated on-chip s Serial
APPLICATIONS
s Automated product calibration. s Remote control adjustment of equipment s Offset, gain and zero adjustments in Self-
Calibrating and Adaptive Control systems.
s Tamper-proof calibrations.
P interface
s Single supply operation: 2.7V-5.5V
DESCRIPTION
The CAT521 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. The CAT521 consists of a programmable DAC with independent high and low reference inputs and is capable of a rail to rail output swing. The output is buffered by a rail to rail OP AMP. Output settings, stored in nonvolatile EEPROM memory, are not lost when the device is powered down and are automatically reinstated when power is returned. The output can be dithered to test new output values without effecting the stored settings FUNCTIONAL DIAGRAM
VDD
and stored settings can be read back without disturbing the DAC's output. Control of the CAT521 is accomplished with a simple 3 wire serial interface. A Chip Select pin allows several CAT521's to share a common serial interface and communications back to the host controller is via a single serial data line thanks to the CAT521'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 CAT521 operates from a single 3-5 volt power supply. The high voltage required for EEPROM Erase/ Write operations is generated on-chip. The CAT521 is available in the 0C to 70C Commercial and -40C to +85C Industrial operating temperature ranges and offered in 14-pin plastic DIP and Surface mount packages. PIN CONFIGURATION
1
DIP Package (P)
6
DO
SOIC Package (J)
VDD CLK RDY/BSY CS DI DO PROG 1 2 3 4 5 6 7 14 13 12 11 10 9 8 VREF H1 NC VOUT1 NC NC VREF L1 GND
RDY/BSY
3
SERIAL DATA OUTPUT
VDD
PROG 7 PROGRAM CONTROL 14 EEPROM LATCH
DAC 1 V REF H1
1 2 3 4 5 6 7
14 13 12 11 10 9 8
VREF H1 NC VOUT1 NC NC VREF L1 GND
CLK RDY/BSY CS DI DO PROG
CAT521
CAT521
+
-
12 9
1 V OUT V REF L1
CLK
2 DATA CONTROLLER
CS
4
DI
5
H.V. CHARGE PUMP
CAT521
8 GND
(c) 2001 by Catalyst Semiconductor, Inc. Characteristics subject to change without notice
1
CAT521
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 RELIABILITY CHARACTERISTICS Symbol
VZAP(1) ILTH(1)(2)
Advanced Information
Operating Ambient Temperature Commercial (`C' suffix) .................... 0C to +70C Industrial (`I' suffix) ...................... - 40C to +85C Junction Temperature ..................................... +150C Storage Temperature ....................... -65C to +150C Lead Soldering (10 sec max) .......................... +300C
* 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.
Parameter
ESD Susceptibility Latch-Up
Min
2000 100
Max
Units
Volts mA
Test Method
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 Accuracy
INL Integral Linearity Error ILOAD = 10 A, ILOAD = 40 A, DNL Differential Linearity Error ILOAD = 10 A, ILOAD = 40 A, TR = C TR = I TR = C TR = I TR = C TR = I TR = C TR = I -- -- -- -- -- -- -- -- -- -- 2 0 2.7 GND -- 0.6 0.6 1.2 1.2 0.25 0.25 0.5 0.5 -- -- -- -- -- -- 28K 1 1 -- -- 0.5 0.5 -- -- 10 -10 VDD 0.8 VDD VDD -2.7 -- LSB LSB LSB LSB LSB LSB LSB LSB A A V V V V
Parameter
Resolution
Conditions
Min
8
Typ
--
Max
--
Units
Bits
Logic Inputs
IIH IIL VIH VIL Input Leakage Current Input Leakage Current High Level Input Voltage Low Level Input Voltage VREFH Input Voltage Range VREFL Input Voltage Range VREFH-VREFL Resistance VIN = VDD VIN = 0V
References
VRH VRL ZIN
Logic Outputs
VOH VOL High Level Output Voltage Low Level Output Voltage IOH = - 40 A IOL = 1 mA, VDD = +5V IOL = 0.4 mA, VDD = +3V VDD -0.3 -- -- -- -- -- -- 0.4 0.4 V V V
2
Advanced Information
DC ELECTRICAL CHARACTERISTICS (Cont.): VDD = +2.7V to +5.5V, VREFH = VDD, VREFL = 0V, unless otherwise specified Symbol
FSO ZSO IL ROUT PSSR TCO TCREF
CAT521
Parameter
Full-Scale Output Voltage Zero-Scale Output Voltage DAC Output Load Current DAC Output Impedance Power Supply Rejection VOUT Temperature Coefficient Temperature Coefficient of VREF Resistance Supply Current (Read) Supply Current (Write) Operating Voltage Range
Conditions
VR = VREFH - VREFL VR = VREFH - VREFL VDD = VREFH = +5V VDD = VREFH = +3V ILOAD = 1 A VDD = +5V, ILOAD = 250nA VREFH= +5V, VREFL = 0V VREFH to VREFL
Min
0.99 VR -- -- -- -- -- -- --
Typ
0.995 VR 0.005 VR -- -- -- -- -- 700
Max
-- 0.01 VR 1 1K 1K 1 200 --
Units
V V A LSB / V V/ C ppm / C
Analog Output
Temperature
Power Supply
IDD1 IDD2 VDD 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
AC ELECTRICAL CHARACTERISTICS: VDD = +2.7V to +5.5V, VREFH = VDD, VREFL = 0V, unless otherwise specified Symbol 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 DAC Settling Time to 1 LSB 150 100 0 50 50 -- -- -- -- -- 150 700 500 300 DC -- -- -- -- -- -- -- -- -- -- -- 400 400 4 -- -- -- -- -- 3 6 8 6 -- -- -- -- -- 150 150 -- -- 5 -- -- -- -- 1 10 10 -- -- ns ns ns ns ns ns ns ns ns ms ns ns ns ns MHz s s pF pF
Parameter
Conditions
Min
Typ
Max
Units
CL = 100 pF, see note 1
Analog
tDS CLOAD = 10 pF, VDD = +5V CLOAD = 10 pF, VDD = +3V VIN = 0V, f = 1 MHz(2) VOUT = 0V, f = 1 MHz(2)
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
CAT521
A. C. TIMING DIAGRAM
Advanced Information
to
1
2
3
4
5
t CLK H CLK
t CSS CS
t CLK L
t CSH
t CSMIN
t DIS DI t DIH
t LZ DO
t DO0
t HZ t DO1
PROG t PS t PROG RDY/BSY t BUSY
to
1
2
3
4
5
4
Advanced Information
PIN DESCRIPTION Pin
1 2 3 4 5 6 7 8 9 10 11 12 13 14
CAT521
DAC addressing is as follows:
Name
VDD CLK RDY/BSY CS DI DO PROG GND VREFL1 NC NC VOUT1 NC VREFH1
Function
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 No Connect No Connect DAC 1 output No Connect Maximum DAC 1 output voltage
DAC OUTPUT VOUT1
A0 0
A1 1
DEVICE OPERATION The CAT521 is a single 8-bit Digital to Analog Converter (DAC) whose output can be programmed to any one of 256 individual voltage steps. Once programmed, the output setting is retained in non-volatile EEPROM memory and will not be lost when power is removed from the chip. Upon power up the DAC returns to the setting stored in EEPROM memory. The DAC can be written to and read from without effecting the output voltage during the read or write cycle. The output can also be adjusted without altering the stored output setting, which is useful for testing new output settings before storing them in memory. DIGITAL INTERFACE The CAT521 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. 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
CHIP SELECT Chip Select (CS) enables and disables the CAT521'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 register 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. CLOCK The CAT521's clock controls both data flow in and out of the device 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 CAT521's internal power-on reset circuitry loads data from EEPROM to the DAC without using the external clock.
CAT521
As data transfers are edge triggered clean clock transitions are necessary to avoid falsely clocking data into the control register. 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. 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. 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 CAT521 will ignore any data appearing at DI and no data will be output on DO. 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 Data is output serially by the CAT521, 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 Figure 1. Writing to Memory
to 1 2 3 4 5 6 7 8 9 10 11 12 N N+1 N+2
Advanced Information
its high impedance Tri-State mode when CS returns low. Tri-Stating the DO pin allows several 521s to share a single serial data line and simplifies interfacing multiple 521s to a microprocessor. WRITING TO MEMORY Programming the CAT521'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. 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 CAT521'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. READING DATA Each time data is transferred into the 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 Ps 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 2. Reading from Memory
to 1 2 3 4 5 6 7 8 9 10 11 12
CS NEW DAC DATA DI 1 A0 A1 D0 D1 D2 D3 D4 D5 D6 D7
CS
DI
1
A0
A1 CURRENT DAC DATA
CURRENT DAC DATA DO D0 D1 D2 D3 D4 D5 D6 D7
DO
D0
D1
D2
D3
D4
D5
D6
D7
PROG
PROG
RDY/BSY
RDY/BSY
DAC OUTPUT
CURRENT DAC VALUE NON-VOLATILE
NEW DAC VALUE VOLATILE
NEW DAC VALUE NON-VOLATILE
DAC OUTPUT
CURRENT DAC VALUE NON-VOLATILE
6
Advanced Information
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. TEMPORARILY CHANGE OUTPUT The CAT521 allows temporary changes in the 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. 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. The temporary setting remains in effect long as CS remains high. When CS returns low the DAC will return to the output value stored in EEPROM memory. 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 CAT521'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
CAT521
Figure 3. Temporary Change in Output
to 1 2 3 4 5 6 7 8 9 10 11 12 N N+1 N+2
CS
NEW DAC DATA 1 A0 A1 D0 D1 D2 D3 D4 D5 D6 D7
DI
CURRENT DAC DATA DO D0 D1 D2 D3 D4 D5 D6 D7
PROG
RDY/BSY
DAC OUTPUT
CURRENT DAC VALUE NON-VOLATILE
NEW DAC VALUE VOLATILE
CURRENT DAC VALUE NON-VOLATILE
DAC INPUT
Vi RI +15V VDD CONTROL & DATA VREF H RF
DAC OUTPUT CODE VDAC = ------ (VFS - VZERO ) + VZERO 255 VFS = 0.99 VREF
ANALOG OUTPUT
- +
-15V
V OUT
MSB 1111
LSB 1111
VZERO = 0.01 VREF 255 ---- (.98 VREF ) + .01 VREF = .990 V REF 255 128 ---- (.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 0 ---- (.98 V ) + .01 V = .010 V REF REF REF 255
VREF = 5V R I = RF V OUT = +4.90V V = +0.02V OUT V = -0.02V OUT V = -4.86V OUT V = -4.90V OUT
OPT 505 CAT521
GND VREF L
OP 07
1000
0000 1111 0001
VOUT = VDAC ( R I+ RF) -VI R F RI For R I = RF VOUT = 2VDAC -VI
0111 0000
0000
0000
Bipolar DAC Output
+5V RI +15V VDD CONTROL & DATA VREF H RF
- +
-15V
VOUT
OPT 505 CAT521
GND VREF L
OP 07
RF VOUT = (1 + ---) V DAC RI
Amplified DAC Output 7
CAT521
APPLICATION CIRCUITS (Cont.)
Advanced Information
28 - 32V
V+
I > 2 mA
15K 10 F
VDD CONTROL & DATA
VREF H
VREF = 5.000V
VDD
1N5231B
VREF H 5.1V 10K CONTROL & DATA
OPT 505 CAT521
GND VREF L
LT 1029
OPT 505 CAT521
GND VREF L
+ - LM 324
MPT3055EL
OUTPUT 4.02 K 1.00K 10 F 35V 0 - 25V @ 1A
Digitally Trimmed Voltage Reference
Digitally Controlled Voltage Reference
8
Advanced Information
CAT521
ORDERING INFORMATION
Prefix CAT Device # 521 Suffix J I -TE13
Optional Company ID
Product Number
Package P: PDIP J: SOIC
2000/Reel
Tape & Reel TE13:
Temperature Range Blank = Commercial (0C to +70C) I = Industrial (-40C to +85C)
Notes: (1) The device used in the above example is a CAT521JI-TE13 (SOIC, Industrial Temperature, Tape & Reel)
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