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DS1388

C RTC/Supervisor with Trickle Charger

and 512 Bytes EEPROM

For pricing, delivery, and ordering information, please contact Maxim Direct at

1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

General Description

The DS1388 I

C real-time clock (RTC), supervisor, and

EEPROM is a multifunction device that provides a

clock/calendar, programmable watchdog timer, power-

supply monitor with reset, and 512 bytes of EEPROM.

The clock provides hundredths of seconds, seconds,

minutes, and hours, and operates in 24-hour or 12-hour

format with an AM/PM indicator. The calendar provides

day, date, month, and year information. The date at the

end of the month is automatically adjusted for months

with fewer than 31 days, including corrections for leap

year. A watchdog timer provides a reset for an unre-

sponsive microprocessor. It is programmable in 10ms

intervals from 0.01 to 99.99 seconds. A temperature-

compensated voltage reference and comparator circuit

monitors the status of V

. If a primary power failure is

detected, the device automatically switches to the

backup supply and drives the reset output to the active

state. The backup supply maintains time and date

operation in the absence of V

. When V

returns to

nominal levels, the reset is held low for a period to allow

the power supply and processor to stabilize. The

device also has a pushbutton reset controller, which

debounces a reset input signal. The device is

accessed through an I

C serial interface.

Applications

Portable Instruments

Point-of-Sale Equipment

Network Interface Cards

Wireless Equipment

Features

o Fast (400kHz) I

C Interface

o RTC Counts Hundredths of Seconds, Seconds,

Minutes, Hours, Day, Date, Month, and Year with

Leap Year Compensation Valid Up to 2100

o Programmable Watchdog Timer

o Automatic Power-Fail Detect and Switch Circuitry

o Reset Output with Pushbutton Reset Input

Capability

o 512 x 8 Bits of EEPROM

o Integrated Trickle-Charge Capability for Backup

Supply

o Three Operating Voltages: 5.0V, 3.3V, and 3.0V

o Low Timekeeping Voltage Down to 1.3V

o -40°C to +85°C Temperature Range

o UL Recognized

TOP VIEW

DS1388

SCL

SDAGND

RSTX2

BACKUP

Pin Configuration

RST

SCL

CPU

SDA

GND

RPU

RPU = t

RPU

CRYSTAL

BACKUP

DS1388

Typical Operating Circuit

19-4984; Rev 4 4/13

Denotes a lead(Pb)-free/RoHS-compliant package.

Ordering Information

PART TEMP RANGE PIN-PACKAGE

TOP

MARK

DS1388Z-5+ -40°C to +85°C 8 SO (150 mils) DS1388-5

DS1388Z-33+ -40°C to +85°C 8 SO (150 mils) DS138833

DS1388Z-3+ -40°C to +85°C 8 SO (150 mils) DS1388-3

Summary of content (19 pages)

PAGE 1
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM General Description Features The DS1388 I2C real-time clock (RTC), supervisor, and o Fast (400kHz) I2C Interface EEPROM is a multifunction device that provides a clock/calendar, programmable watchdog timer, powersupply monitor with reset, and 512 bytes of EEPROM. The clock provides hundredths of seconds, seconds, minutes, and hours, and operates in 24-hour or 12-hour format with an AM/PM indicator.
PAGE 2
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM ABSOLUTE MAXIMUM RATINGS Voltage Range on VCC or VBACKUP Pins Relative to Ground.............................................-0.3V to +6.0V Voltage Range on Inputs Relative to Ground ...............................................-0.3V to (VCC + 0.3V) Junction-to-Ambient Thermal Resistance (θJA) (Note 1)..170°C/W Junction-to-Case Thermal Resistance (θJC) (Note 1) ......40°C/W Note 1: Operating Temperature Range (noncondensing) ............
PAGE 3
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM DC ELECTRICAL CHARACTERISTICS (continued) (VCC = VCC(MIN) to VCC(MAX), TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER RST Logic 0 Output VCC Active Current, EEPROM 2 Read, I C Read/Write Access VCC Active Current, EEPROM Write Cycle SYMBOL IOLSIR ICCER ICCEW CONDITIONS MIN TYP VCC > 2V; VOL = 0.4V 3.0 1.8V < VCC < 2V; VOL = 0.2 x VCC 3.0 1.3V < VCC < 1.8V; VOL = 0.
PAGE 4
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM AC ELECTRICAL CHARACTERISTICS (VCC = VCC(MIN) to VCC(MAX), TA = -40°C to +85°C, unless otherwise noted.
PAGE 5
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM POWER-UP/POWER-DOWN CHARACTERISTICS (TA = -40°C to +85°C) (Note 2) (Figures 1, 2) PARAMETER SYMBOL VCC Detect to Recognize Inputs (VCC Rising) tRST VCC Fall Time; VPF(MAX) to V PF(MIN) VCC Rise Time; V PF(MIN) to V PF(MAX) CONDITIONS MIN TYP MAX UNITS 160 180 ms (Note 18) tF 300 μs tR 0 μs VCC VPF(MAX) VPF VPF VPF(MIN) tF tR tRPU tRST RST RECOGNIZED INPUTS DON'T CARE RECOGNIZED HIGH IMPEDANCE OUTPUTS VALID VA
PAGE 6
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM WARNING: Under no circumstances are negative undershoots, of any amplitude, allowed when device is in write protection. Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: Note 10: Note 11: Note 12: Note 13: Note 14: Note 15: Note 16: Note 17: Note 18: 6 Limits at -40°C are guaranteed by design and are not production tested. All voltages are referenced to ground.
PAGE 7
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Typical Operating Characteristics (VCC = +3.3V, TA = +25°C, unless otherwise noted.) IBACKUP SUPPLY CURRENT VOLTAGE vs. TEMPERATURE IBACKUP SUPPLY CURRENT VOLTAGE vs. VBACKUP VBACKUP = 3V 550 SUPPLY CURRENT (nA) 450 400 350 DS1388 toc02 VCC = 0V SUPPLY CURRENT (nA) 600 DS1388 toc01 500 500 450 400 350 300 300 250 250 1.3 1.7 2.1 2.5 2.9 3.3 3.7 4.1 4.5 4.9 5.
PAGE 8
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Pin Description PIN NAME 1 X1 2 X2 FUNCTION Connections for a Standard 32.768kHz Quartz Crystal. The internal oscillator circuitry is designed for operation with a crystal having a specified load capacitance (CL) of 6.0pF. Pin X1 is the input to the oscillator and can optionally be connected to an external 32.768kHz oscillator.
PAGE 9
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Detailed Description The DS1388 I2C RTC, supervisor, and EEPROM is a multifunction device that provides a clock/calendar, programmable watchdog timer, power-supply monitor with reset, and 512 bytes of EEPROM. The clock provides hundredths of seconds, seconds, minutes, and hours, and operates in 24-hour or 12-hour format with an AM/PM indicator. The calendar provides day, date, month, and year information.
PAGE 10
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM LOCAL GROUND PLANE (LAYER 2) X1 CRYSTAL X2 NOTE: AVOID ROUTING SIGNAL LINES IN THE CROSSHATCHED AREA (UPPER LEFT QUADRANT) OF THE PACKAGE UNLESS THERE IS A GROUND PLANE BETWEEN THE SIGNAL LINE AND THE DEVICE PACKAGE. GND Figure 3.
PAGE 11
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM ADDRESS BLK WORD 0h 00h BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 Tenth Seconds BIT 2 BIT 1 BIT 0 FUNCTION RANGE Hundredths of Seconds Hundredths of Seconds 00–99 0h 01h 0 10 Seconds Seconds Seconds 00–59 0h 02h 0 10 Minutes Minutes Minutes 00–59 0h 03h 0 12/24 AM/ PM Hours Hours 1–12+ AM/PM 00–23 0h 04h 0 0 0 0h 05h 0 0 0h 06h 0 0 0h 07h 0h 10 Hour 10 Hour 0 X Day 01–07 Date Day Date 01–3
PAGE 12
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Watchdog Alarm Counter The contents of the watchdog alarm counter, which is a separate two-byte BCD down counter, are accessed in the address range 08h–09h in block 0h. It is programmable in 10ms intervals from 0.01 to 99.99 seconds. When this counter is written, both the counter and a seed register are loaded with the desired value. When the counter is to be reloaded, it uses the value in the seed register.
PAGE 13
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Control Register (00Ch) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 EOSC 0 0 0 0 0 WDE WD/RST Control Register (00Ch) Bit 7: Enable Oscillator (EOSC). When set to logic 0, the oscillator is started. When set to logic 1, the oscillator is stopped when the DS1388 switches to battery power. This setting can be used to conserve battery power when timekeeping operation is not required.
PAGE 14
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM TRICKLE-CHARGE REGISTER (00Ah) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 TCS3 TCS2 TCS1 TCS0 DS1 DS0 1 0F 16 SELECT NOTE: ONLY 1010b ENABLES CHARGER BIT 1 BIT 0 ROUT1 ROUT0 1 OF 2 SELECT TCS0-3 = TRICKLE-CHARGE SELECT DS0-1 = DIODE SELECT ROUT0-1 = RESISTOR SELECT 1 OF 3 SELECT R1 250Ω R2 2kΩ VCC VBACKUP R3 4kΩ Figure 5.
PAGE 15
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Each data transfer is initiated with a START condition and terminated with a STOP condition. The number of data bytes transferred between the START and the STOP conditions is not limited, and is determined by the master device. The information is transferred byte-wise and each receiver acknowledges with a ninth bit. Figures 7 and 8 detail how data transfer is accomplished on the I2C bus.
PAGE 16
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Device Addressing The slave address byte is the first byte received following the START condition from the master device. The slave address byte consists of a 4-bit control code. For the DS1388, this is set as 1101 binary for read and write operations. The next three bits of the slave address byte are the block select bits (B2, B1, B0). B2 is always logic 0 for the DS1388.
PAGE 17
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Acknowledge Polling Since the DS1388 does not acknowledge during an EEPROM write cycle, acknowledge polling can be used to determine when the cycle is complete (this feature can be used to maximize bus throughput). Once the master issues the STOP condition for a write command, the DS1388 initiates the internally timed write cycle. ACK polling can be initiated immediately.
PAGE 18
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM S 1101BBB 1 XXXXXXXX A A B - BLOCK SELECT MASTER TO SLAVE S - START A - ACKNOWLEDGE (ACK) P - STOP A - NOT ACKNOWLEDGE (NACK) R/W - READ/WRITE OR DIRECTION BIT ADDRESS XXXXXXXX A XXXXXXXX A ... XXXXXXXX A P SLAVE TO MASTER DATA TRANSFERRED (X + 1 BYTES + ACKNOWLEDGE) NOTE: LAST DATA BYTE IS FOLLOWED BY A NACK. Figure 8.
PAGE 19
DS1388 I2C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM Revision History REVISION NUMBER REVISION DATE 0 4/05 DESCRIPTION Initial release. — Removed the leaded parts from the Ordering Information. 1 Indicated the pullup voltage for SDA and SCL in the Pin Description table. Added the oscillator bias circuit to the Block Diagram and removed the original Figure 1 9/08 10/09 3 8/10 4 4/13 8 8, 10 Added time and date POR values in the Power Control section.