MAXWELL 7820RPDS, 7820RPDI, 7820RPDE, 7820RPDB Datasheet

7820

Microprocessor-compatible

8-Bit ADC

FEATURES:

• 1.36 µs Conversion Time

• Built-in-Track-and-Hold Function

• Single +5 Volt Supply

• No External Clock Required

• Tri-State Output Buffered

• Total Ionization Dose:

- > 50 krads (Si), depending upon space mission.

• Excellent Single Event Effects

- SEL > 80 MeV/mg/cm

• Package:

- 20 pin Rad-Pak DIP

2

Logic Diagram

DESCRIPTION:

The 7820 is a microprocessor compatible 8-bit Analog-to-Digi­tal Converter with a 0V to +5V input supply range with a single
+5 Volt supply.

The 7820 incorporates internal sample-and-hold circuitry
which eliminates the need for an external S/H for signals with
slew rates less than 100 mV/µs.

The 7820 was designed to be easiliy interfaced with micropro­cessors, appearing as either a memory location or I/O port
without the need for external interfacing. All outputs are
latched and tri-state buffered.

Maxwell Technologies' patented R
ogy incorporates radiation shielding in the microcircuit pack­age. It eliminates the need for box shielding while providing
the required radiation shielding for a lifetime in orbit or space
mission. In a GEO orbit, R
krad (Si) radiation dose tolerance. This product is available
with screening up to Class S.

AD-PAK® packaging technol-

AD-PAK provides greater than 100

Memory

1000564

[phone] - Fax: [phone] - www.maxwell.com

12.19.01 Rev2

All data sheets are subject to change without notice

©2001 Maxwell Technologies

All rights reserved.

1

Microprocessor-compatible 8-Bit ADC

TABLE 1. PIN DESCRIPTION

PIN SYMBOL DESCRIPTION

7820

1VINAnalog Input Range: V

REF(-)

to V

REF(+)

.

2 DB0 Data Output. Three State Output, bit 0 (LSB)

3 DB1 Data Output. Three State Output, bit 1

4 DB2 Data Output. Three State Output, bit 2

5 DB3 Data Output. Three State Output, bit 3

6WR

/RDY WRITE control input/READY status output.

7 Mode Mode Selection Input. It determines whether the device operates in the

WR-RD or RD mode. It is internally tied to GND through a 50 µA current
source.

8RD

9INT

READ Input. RD must be low to access data from the part.

INTERUPT Output. INT going low indicates that the conversion is com­plete INT

returns high on rising the edge of RD or CS.

10 GND Ground

11 V

12 V

REF-

REF+

Lower limit of reference span. Range: GND < V

Upper limit of reference span. Range: GND < V

REF(-)

REF(-)

< V

< V

REF(+)

REF(+)

< V

DD

13 CS Chip Select Input. CS, the decoded device address, must be low for RD

or WR

to be recognized by the converter.

14 DB4 Data Output. Three State Output, bit 4

15 DB5 Data Output. Three State Output, bit 5

Memory

16 DB6 Data Output. Three State Output, bit 6

17 DB7 Data Output. Three State Output, bit 7 (MSB)

18 OFL

Overflow Output. If the analog input is higher than (V

REF(+)

OFL will be low at the end of conversion. It is a non three state output
which can be used to cascade 2 or more devices to increase resolution.

19 NC No Connection.

20 V

DD

Power supply voltage, +5V

TABLE 2. 7820 ABSOLUTE MAXIMUM RATINGS

1

PARAMETER MIN MAX UNIT

VDD to GND -0 7.0 V

Digital Input Voltage to GND (Pins 6-80, 13) -0.3 V

Digital Output Voltage to GND (Pins 2-5, 9, 14-18) 0.3 V

V

(+) to GND 0 VDD +0.3 V

REF

V

(-) to GND VSS -0.3 V

REF

1000564

12.19.01 Rev2

All data sheets are subject to change without notice

DD

DD

REF

- 1/2LSB),

+0.3 V

+0.3 V

(+) V

2

©2001 Maxwell Technologies

All rights reserved.

Microprocessor-compatible 8-Bit ADC

7820

TABLE 2. 7820 ABSOLUTE MAXIMUM RATINGS

1

PARAMETER MIN MAX UNIT

VIN to GND -0.3 VDD +0.3 V

Operating Temperature -55 125 °C

Storage Temperature Range -65 150 °C

Power Dissipation to 75°C -- 450 mW

Derates above +75°C -- 6 mW/°C

1. CAUTION: ESD (electrostatic discharge) sensitive device. The digital control inputs are diode protected; how­ever, permanent damage may occur on unconnected devices subject to high energy electrostatic fields. Unused
devices must be stored in conductive foam or shunts. The protective foam should be discharged to the destina­tion socket before devices are inserted.

TABLE 3. 7820 DC ELECTRICAL CHARACTERISTICS

(VDD = +5V; VREF(+) = +5V; VREF(-) = GND = 0V, UNLESS OTHERWISE SPECIFIED) (RD MODE (PIN 7 = 0V))

(T

= -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)

A

P

ARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Accuracy

Resolution -- 8 -- -- Bits

Total Unadjusted Error

1

-- -- -- ±1.0 LSB

Memory

Minimum Resolution for which No

-- -- -- 8 Bits

Missing Codes are Guaranteed

Reference Input

Input Resisitance -- 1.0 -- 4.0 k

V

(+) Input Voltage Range -- V

REF

V

(-) Input Voltage Range -- GND -- V

REF

(-) -- V

REF

DD

(+) V

REF

Ω

V

Analog Input

Input Voltage Range -- V

(-) -- V

REF

(+) V

REF

Input Leakage Current -- -- -- ±3 µA

Input Capacitance

2

-- -- 45 -- pF

Logic Inputs

CS

, WR, RD

V

INH

V

INH

I

(CS, RD)------1µA

INH

I

(WR)------3µA

INH

I

(WR)-------1µA

INL

Input Capacitance

2

-- 2.4 ----V

-- -- -- 0.8 V

-- -- 5 8 pF

Mode

1000564

12.19.01 Rev2

All data sheets are subject to change without notice

©2001 Maxwell Technologies

All rights reserved.

3

Microprocessor-compatible 8-Bit ADC

TABLE 3. 7820 DC ELECTRICAL CHARACTERISTICS

(VDD = +5V; VREF(+) = +5V; VREF(-) = GND = 0V, UNLESS OTHERWISE SPECIFIED) (RD MODE (PIN 7 = 0V))

(T

= -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)

A

P

ARAMETER TEST CONDITIONS MIN TYP MAX UNIT

7820

V

INH

-- 3.5 ----V

--

V

INH

I

INH

I

INL

-- -- -- 1.5 V

-- -- -- 200 µA

-- -- -- -1 µA

--

--

Input Capacitance

2

-- -- 5 8 pF

Logic Outputs

DB0-DB7, OFL

V

OH

V

OL

I

(DB0-DB7) Floating State Leakage -- -- ±3 µA

OUT

Output Capacitance

, INT --

ISOURCE = 360 µA 4 -- -- V

ISINK = 1.6 mA -- -- 0.4 V

2

-- -- 5 8 pF

RDY

V

I

OL

OUT

ISINK = 2.6mA -- -- 0.4 V

Floating State Leakage -- -- ±3 V

Output Capacitance -- -- 5 8 pF

Slew Rate, Tracking

2

-- -- 0.2 0.1 V/µs

Power Supply

V

DD

±5% for specified perfor-

-- -- 5 V

mance

Memory

I

DD

CS = RD = OV -- -- 20 mA

Power Dissipation -- -- 40 -- mW

Power Supply Sensitivity VDD = 5V ±5% -- ±1/16 ±1/4 LSB

1. Total unadjusted error includes offset, full scale and linearity error.

2. Not tested.

1000564

12.19.01 Rev2

All data sheets are subject to change without notice

©2001 Maxwell Technologies

All rights reserved.

4

Microprocessor-compatible 8-Bit ADC

7820

TABLE 4. 7820 AC ELECTRICAL CHARACTERISTICS

1

(VDD = +5V; VREF(+) = +5V; VREF(-) = GND = 0V, UNLESS OTHERWISE SPECIFIED) (RD MODE (PIN 7 = 0V))

(T

= -55 TO 125 °C UNLESS OTHERWISE SPECIFIED)

A

ARAMETER SYMBOL MIN MAX UNIT

P

CS to RD/WR Setup Time t

CS

to RD/WR Hold Time t

CS

to Delay Time (Pull-up Resistor = 5kΩ t

Conversion Time (RD Mode) t

Data Access Time (RD Mode) t

RD

to INT Delay (RD Mode) t

Data Hold Time t

Delay Time Between Conversions t

Write Pulse Width t

CSS

CSH

RDY

CRD

ACCD

INTH

DH

p

WR

0--ns

0--ns

-- 100 ns

-- 2.5 µs

-- t

+ 50 ns

CRD

-- 225 ns

-- 100 ns

600 -- ns

600 -- ns

-- 50 µs

Delay Time Between WR and RD Pulses t

Data Access Time (WR-RD Mode) t

RD to INT Delay t

WR to INT Delay t

Data Access Time (WR-RD Mode) t

WR to INT Delay (Stand-Alone Operation) t

Data Access Time After INT (Stand-Alone Operation t

RD

ACC1

R1

INTL

ACC2

IHWR

ID

700 -- ns

-- 250 ns

-- 225 ns

-- 1700 ns

-- 110 ns

-- 150 ns

-- 75 ns

Memory

1. Sample tested at 25°C to ensure compliance. Only on process design change.

1000564

12.19.01 Rev2

All data sheets are subject to change without notice

5

©2001 Maxwell Technologies

All rights reserved.

Microprocessor-compatible 8-Bit ADC

FIGURE 1. LOAD CIRCUITS FOR DATA ACCESS TIME TEST

7820

Memory

FIGURE 2. LOAD CIRCUITS FOR DATA HOLD TIME RESET

1000564

12.19.01 Rev2

All data sheets are subject to change without notice

©2001 Maxwell Technologies

All rights reserved.

6