Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsIntegrated Circuits (ICs)Timer IC t- real time clock Clock/calendar SOIC 20 W

General Description

The DS3234 is a low-cost, extremely accurate SPI™ bus

real-time clock (RTC) with an integrated temperature-com-

pensated crystal oscillator (TCXO) and crystal. The

DS3234 incorporates a precision, temperature-compen-

sated voltage reference and comparator circuit to monitor

. When V

drops below the power-fail voltage (V

the device asserts the RST output and also disables read

and write access to the part when V

drops below both

and V

BAT

. The RST pin is monitored as a pushbutton

input for generating a µP reset. The device switches to the

backup supply input and maintains accurate timekeeping

when main power to the device is interrupted. The integra-

tion of the crystal resonator enhances the long-term accu-

racy of the device as well as reduces the piece-part count

in a manufacturing line. The DS3234 is available in com-

mercial and industrial temperature ranges, and is offered

in an industry-standard 300-mil, 20-pin SO package.

The DS3234 also integrates 256 bytes of battery-backed

SRAM. In the event of main power loss, the contents of

the memory are maintained by the power source con-

nected to the V

BAT

pin. The RTC maintains seconds,

minutes, hours, day, date, month, and year information.

The date at the end of the month is automatically adjust-

ed for months with fewer than 31 days, including correc-

tions for leap year. The clock operates in either the

24-hour or 12-hour format with AM/PM indicator. Two

programmable time-of-day alarms and a programmable

square-wave output are provided. Address and data are

transferred serially by an SPI bidirectional bus.

Applications

Servers Utility Power Meters

Telematics GPS

Features

♦ Accuracy ±2ppm from 0°C to +40°C

♦ Accuracy ±3.5ppm from -40°C to +85°C

♦ Battery Backup Input for Continuous

Timekeeping

♦ Operating Temperature Ranges

Commercial: 0°C to +70°C

Industrial: -40°C to +85°C

♦ Low-Power Consumption

♦ Real-Time Clock Counts Seconds, Minutes,

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

Compensation Valid Up to 2099

♦ Two Time-of-Day Alarms

♦ Programmable Square-Wave Output

♦ 4MHz SPI Bus Supports Modes 1 and 3

♦ Digital Temp Sensor Output: ±3°C Accuracy

♦ Register for Aging Trim

♦ RST Input/Output

♦ 300-Mil, 20-Pin SO Package

♦ Underwriters Laboratories Recognized

DS3234

Extremely Accurate SPI Bus RTC with

Integrated Crystal and SRAM

______________________________________________

Maxim Integrated Products

19-5339; Rev 3; 7/10

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

PART TEMP RANGE

PIN-

PACKAGE

TOP

MARK

DS3234S# 0°C to +70°C 20 SO DS3234S

DS3234SN# -40°C to +85°C 20 SO DS3234SN

DS3234

INT/SQW

32kHz

BAT

PUSH-

BUTTON

RESET

SCLK

RST

N.C.

GND

μP

SCLK

DIN

MOSI

DOUT

MISO

RST

N.C.

Typical Operating Circuit

Denotes a RoHS-compliant device that may include lead that

is exempt under the RoHS requirements. Lead finish is JESD97

Category e3, and is compatible with both lead-based and

lead-free soldering processes. A "#" anywhere on the top mark

denotes a RoHS-compliant device.

TOP VIEW

SCLK

DOUT

SCLK

DINV

32kHz

N.C.

BAT

GND

N.C.

N.C.N.C.

N.C.

RST

INT/SQW

N.C.

N.C.N.C.

N.C.

DS3234

Pin Configuration

SPI is a trademark of Motorola, Inc.

Summary of content (21 pages)

PAGE 1
9-5339; Rev 3; 7/10 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM Features The DS3234 is a low-cost, extremely accurate SPI™ bus real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal. The DS3234 incorporates a precision, temperature-compensated voltage reference and comparator circuit to monitor VCC.
PAGE 2
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground......-0.3V to +6.0V Junction-to-Ambient Thermal Resistance (θJA) (Note 1) ...55°C/W Junction-to-Case Thermal Resistance (θJC) (Note 1) ........24°C/W Operating Temperature Range (noncondensing) .............................................-40°C to +85°C Junction Temperature ......................................................+125°C Storage Temperature Range ........
PAGE 3
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM (VCC = 2.0V to 5.5V, VCC = active supply (see Table 1), TA = -40°C to +85°C, unless otherwise noted.) (Typical values are at VCC = 3.3V, VBAT = 3.0V, and TA = +25°C, unless otherwise noted. TCXO operation guaranteed from 2.3V to 5.5V on VCC and 2.3V to 3.8V on VBAT.) (Notes 2, 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.4 V Logic 0 Output, 32kHz VOL IOL = 1mA Logic 1 Output, DOUT VOH IOH = -1.
PAGE 4
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM AC ELECTRICAL CHARACTERISTICS (VCC = 2.0V to 5.5V, TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER SCLK Clock Frequency SYMBOL fSCL CONDITIONS MIN TYP MAX 2.7V ≤ VCC ≤ 5.5V 4 2.0V ≤ VCC < 2.
PAGE 5
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM RST PBDB tRST Power-Switch Timing VCC VPF(MAX) VPF VPF(MIN) tVCCF VPF tVCCR tREC RST WARNING: Negative undershoots below -0.3V while the part is in battery-backed mode may cause loss of data. Limits at -40°C are guaranteed by design and not production tested. All voltages are referenced to ground. Measured at VIH = 0.8 x VCC or VIL = 0.2 x VCC, 10ns rise/fall time, DOUT = no load.
PAGE 6
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM DS3234 Timing Diagram—SPI Read Transfer CS tCCS tCC tR tF SCLK tCL tCDZ tCH tCDH tCDD tDC DIN A6 W/R A0 DOUT D7 HIGH IMPEDANCE WRITE ADDRESS BYTE D0 READ DATA BYTE NOTE: SCLK CAN BE EITHER POLARITY, SHOWN FOR CPOL = 1.
PAGE 7
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM BATTERY CURRENT vs. SUPPLY VOLTAGE 2350 50 850 1850 1600 1350 1100 25 3.8 4.3 4.8 700 600 2.3 5.3 VBAT = 3.0V 3.3 2.8 VCC (V) 3.8 -40 -20 SUPPLY VOLTAGE (VBAT) FREQUENCY DEVIATION vs. TEMPERATURE vs. AGING VALUE 500 SUPPLY CURRENT (μA) 45 AGING = -33 35 25 AGING = 0 15 5 -5 -15 AGING = 127 -25 450 400 SCLK = 4MHz 350 300 250 AGING = 32 -35 80 DS3234 toc05 AGING = -128 55 60 ICCA vs.
PAGE 8
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM Pin Description PIN NAME 1 CS 2, 7–14 N.C. 3 32kHz 4 VCC 5 8 FUNCTION Active-Low Chip Select Input. Used to select or deselect the device. No Connection. Not connected internally. Must be connected to ground. 32kHz Push-Pull Output. If disabled with either EN32kHz = 0 or BB32kHz = 0, the state of the 32kHz pin will be low. DC Power Pin for Primary Power Supply. This pin should be decoupled using a 0.1µF to 1.0µF capacitor.
PAGE 9
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM 32kHz X1 OSCILLATOR AND CAPACITOR ARRAY INT/SQW CONTROL LOGIC/ DIVIDER X2 SQUARE-WAVE BUFFER; INT/SQW CONTROL N VCC VOLTAGE REFERENCE; DEBOUNCE CIRCUIT; PUSHBUTTON RESET DS3234 RST N VCC VBAT POWER CONTROL TEMPERATURE SENSOR GND CONTROL AND STATUS REGISTERS SRAM CS SCLK SCLK CLOCK AND CALENDAR REGISTERS SPI INTERFACE AND ADDRESS REGISTER DECODE DIN USER BUFFER (7 BYTES) DOUT Detailed Description The DS3234 is a TCXO and RT
PAGE 10
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM 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. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. Access to the internal registers is possible through an SPI bus interface.
PAGE 11
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM Real-Time Clock With the clock source from the TCXO, the RTC provides seconds, minutes, hours, 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. The clock operates in either the 24-hour or 12-hour format with an AM/PM indicator. The clock provides two programmable time-of-day alarms and a programmable square-wave output.
PAGE 12
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM Figure 1.
PAGE 13
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM The DY/DT bits (bit 6 of the alarm day/date registers) control whether the alarm value stored in bits 0 to 5 of that register reflects the day of the week or the date of the month. If DY/DT is written to logic 0, the alarm will be the result of a match with date of the month. If DY/DT is written to logic 1, the alarm will be the result of a match with day of the week. The DS3234 contains two time-of-day/date alarms.
PAGE 14
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM Control Register (0Eh/8Eh) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 NAME: EOSC BBSQW CONV RS2 RS1 INTCN A2IE A1IE POR*: 0 0 0 1 1 1 0 0 *POR is defined as the first application of power to the device, either VBAT or VCC. Special-Purpose Registers The DS3234 has two additional registers (control and control/status) that control the real-time clock, alarms, and square-wave output.
PAGE 15
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 NAME: OSF BB32kHz CRATE1 CRATE0 EN32kHz BSY A2F A1F POR*: 1 1 0 0 1 0 0 0 *POR is defined as the first application of power to the device, either VBAT or VCC. Control/Status Register (0Fh/8Fh) Bit 7: Oscillator Stop Flag (OSF).
PAGE 16
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM Aging Offset (10h/90h) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 NAME: SIGN DATA DATA DATA DATA DATA DATA DATA POR*: 0 0 0 0 0 0 0 0 Temperature Register (MSB) (11h) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 NAME: SIGN DATA DATA DATA DATA DATA DATA DATA POR*: 0 0 0 0 0 0 0 0 Temperature Register (LSB) (12h) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 NAME: DATA
PAGE 17
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 NAME: 0 0 0 0 0 0 0 BB_TD POR*: 0 0 0 0 0 0 0 0 *POR is defined as the first application of power to the device, either VBAT or VCC.
PAGE 18
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM Address and data bytes are shifted MSB first into the serial data input (DIN) and out of the serial data output (DOUT). Any transfer requires the address of the byte to specify a write or read, followed by one or more bytes of data. Data is transferred out of the DOUT pin for a read operation and into the DIN for a write operation (Figures 3 and 4). The address byte is always the first byte entered after CS is driven low.
PAGE 19
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM DS3234 CS SCLK DIN WRITE ADDRESS BYTE DATA BYTE 0 DATA BYTE 1 DATA BYTE N DIN ADDRESS BYTE READ DOUT HIGH IMPEDANCE DATA BYTE 0 DATA BYTE 1 DATA BYTE N Figure 5. SPI Multiple-Byte Burst Transfer Data transfers can occur one byte at a time or in multiple-byte burst mode. After CS is driven low, an address is written to the DS3234. After the address, one or more data bytes can be written or read.
PAGE 20
DS3234 Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM Package Information Chip Information SUBSTRATE CONNECTED TO GROUND PROCESS: CMOS 20 For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
PAGE 21
Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM REVISION NUMBER REVISION DATE 0 2/06 Initial release — 7/07 Clarified the behavior of tREC on initial power-up in the RST description of the Pin Description 8 1 Corrected the POR for the BB32kHz bit from 0 to 1 15 Updated the Typical Operating Circuit 1 DESCRIPTION Removed the VPU parameter from the Recommended DC Operating Conditions table and added verbiage about the pullup to the Pin Description table for INT/SQW 2 10/08 7/