DS1221 datasheet(5/8 Pages) DALLAS

5 / 8 page

DS1221

5 of 8

CAPACITANCE

(tA = 25°C)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS

NOTES

Input Capacitance

CIN

5pF

Output Capacitance

COUT

7pF

AC ELECTRICAL CHARACTERISTICS

°C to 70°C; V

CC = 4.5 to 5.5V)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS

NOTES

Propagation Delay

tPD

515

High to Power-Fail

tPF

0ns

Address Setup

tAS

°C to 70°C; V

CC < 4.5V)

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS

NOTES

Recovery at Power-Up

tREC

VCC Slew Rate 4.5 - 4.25V

300

µs

VCC Slew Rate 4.25 - 3V

tFB

µs

VCC Slew Rate 4.25 - 4.5V

0µs

Pulse Width

tCE

1.5

µs

7, 8

NOTES:

1. All voltages are referenced to ground.

2. Only one battery input is required.

3. Measured with VCCO and CE0 - CE3 open.

4. ICCO1 is the maximum average load which the DS1221 can supply to the memories.

5. Measured with a load as shown in Figure 4.

6. ICCO2 is the maximum average load current which the DS1221 can supply to the memories in the

battery back-up mode.

7. Chip enable outputs CE0 - CE3 can only sustain leakage current in the battery back-up mode.

8. tCE max. must be met to ensure data integrity on power loss.

9. tAS is only required to keep the decoder outputs glitch-free. While CE is low, the outputs ( CE0 - CE3 )

will be defined by inputs A and B with a propagation delay of tPD from an A or B input change.

10. For applications where higher currents are required, please see the DS1259 Battery Manager Chip

data sheet.

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