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Analog Devices Inc./Maxim Integrated DS17885E-5
- Part No.:
- DS17885E-5
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Real Time Clocks
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
DS17885E-5.pdf
- Description:
- IC RTC CLK/CALENDAR PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,010
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Product details
Overview
DS17885E-5 from Maxim Integrated is a battery-backed real-time clock/calendar IC with 8kB extended NV SRAM, 114 bytes of general-purpose NV SRAM, time-of-day alarm, six maskable interrupts, and programmable square-wave output. It operates at +3.0V or +5.0V, supports 12-/24-hour format with leap-year compensation through 2099, and integrates power-on control via PWR and KS pins for embedded system wake-up. Used in utility meters and security systems requiring long-term timekeeping during main power loss.
For engineers reviewing the DS17885E-5 datasheet, DS17885E-5 pinout, DS17885E-5 application, or DS17885E-5 equivalent, this page delivers verified technical context, exact pin functions, real-world timing and power specifications, and validated alternative options - all grounded in Maxim's official DS17885 documentation and electrical characteristics.
Technical Context
The DS17885E-5 implements a multiplexed byte-wide bus interface (AD0–AD7) with ALE-controlled address latching, supporting read/write cycles down to 240ns at 5V and 360ns at 3V. Its RTC core uses an external 32.768kHz crystal (6pF or 12.5pF load), with oscillator enable/disable controlled by DV bits in Register A and automatic power-fail detection switching to VBAT or VBAUX.
Power management includes dual backup inputs (VBAT and VBAUX), software-controllable PWR output for system power-on, and hardware kickstart via KS pin. The device features double-buffered time/calendar registers, a 64-bit silicon serial number, and bank-switched extended register space (Bank 0/Bank 1) for accessing century and extended alarm registers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | +2.7V to +3.7V or +4.5V to +5.5V - supports dual-voltage system integration without level shifters |
| Backup Supply Current | 500–700nA at 3.0V - enables >10-year data retention on coin-cell battery |
| RTC Accuracy | Factory-trimmed ±1 min/month (when used as DS17887 EDIP); standalone DS17885E-5 accuracy depends on external crystal matching |
| SRAM Capacity | 114 bytes general-purpose + 8192 bytes extended NV SRAM - sufficient for firmware state logging and configuration storage |
| Interrupt Capability | Six independently maskable flags (AF, UF, PF, IRQF, etc.) sharing single IRQ output - simplifies interrupt handling in resource-constrained MCUs |
| Timing Interface | 240ns cycle time (5V), 360ns (3V); tREC = 20–150ms power-up recovery - defines minimum CPU bus access timing margins |
| Crystal Support | 6pF or 12.5pF load capacitance selectable via Crystal Select bit - accommodates common off-the-shelf 32.768kHz crystals |
Pinout & Package
DS17885E-5 is available in 28-pin SO package (SOIC-28), pin-compatible with industry-standard DS12887 footprint. Package dimensions: 17.9mm × 7.6mm × 2.3mm (JEDEC MS-013AC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| AD0–AD7 | Multiplexed address/data bus | Shares 8 pins for both address and data - reduces MCU GPIO count; requires ALE strobe for demultiplexing |
| CS, RD, WR, ALE | Control signals | Standard 8080-style bus protocol - compatible with legacy x86, ARM, and microcontroller memory-mapped peripherals |
| IRQ | Open-drain interrupt output | Active-low, high-impedance when inactive - allows wired-OR with other interrupt sources |
| PWR | Active-low system power-control output | Drives external power supply enable - enables full system wake-up from RTC alarm or key press (KS) |
| KS | Active-low kickstart input | Triggers PWR assertion when VCC is absent - used for manual wake-up (e.g., front-panel button) |
| VBAT / VBAUX | Dual backup supply inputs | VBAT powers RTC core; VBAUX enables KS/PWR functionality and extends RAM retention - supports redundant backup schemes |
| SQW | Programmable square-wave output | Configurable 1Hz–32kHz output (13 tap points) - usable as system clock source or timing reference for auxiliary circuits |
Key Features
| Feature | Design Value |
|---|---|
| 8kB extended NV SRAM | Enables persistent storage of firmware parameters, event logs, or calibration data without external EEPROM |
| Software-controllable PWR output | Allows MCU to sequence system power-down after task completion - critical for energy-efficient embedded designs |
| 64-bit silicon serial number | Provides unique device identity for secure boot, licensing, or field asset tracking without external OTP memory |
| Leap-year compensation through 2099 | Eliminates date rollover bugs in long-life deployments - no host software correction required |
| Crystal select bit (6pF/12.5pF) | Removes need for board-level capacitor changes - supports multiple crystal vendors across production batches |
Applications
| Utility Metering | Security Systems |
|---|---|
|
Use Scenario: Smart electricity meter recording kWh consumption with timestamped tamper events and tariff switching. IC Role / Device Role / Timing Role: Primary RTC and nonvolatile event log storage - maintains accurate time and stores up to 10 years of tamper timestamps in 8kB extended SRAM. Use Value: Eliminates reliance on host MCU for timekeeping during power outages; retains metering integrity even if main processor fails. |
Use Scenario: Access control panel logging door-open events, card swipes, and alarm triggers with precise timestamps. IC Role / Device Role / Timing Role: Time-stamping engine and secure audit trail buffer - uses 114-byte RAM for recent events and 8kB SRAM for long-term history. Use Value: Ensures chain-of-custody compliance by guaranteeing timestamp authenticity independent of system clock drift or reset. |
| Network Infrastructure | Industrial HMI |
|
Use Scenario: Managed Ethernet switch maintaining uptime statistics, SNMP trap timestamps, and firmware update logs. IC Role / Device Role / Timing Role: System timebase and configuration persistence - synchronizes NTP client startup and stores last-boot time in battery-backed RAM. Use Value: Enables accurate network diagnostics and root-cause analysis by correlating events across distributed devices with sub-second precision. |
Use Scenario: Human-machine interface terminal recording operator actions, alarm acknowledgments, and maintenance cycles. IC Role / Device Role / Timing Role: Local timekeeper and session-state recorder - timestamps UI interactions and saves state to extended SRAM before power loss. Use Value: Prevents data loss during unexpected AC failure; restores UI context on reboot using retained timestamps and action history. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar real-time clock applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS17887-5 | Same RTC core and register map, but integrates quartz crystal and lithium battery in 24-pin EDIP package - no external crystal or VBAT circuitry needed | Used where board space is constrained and factory-calibrated accuracy (±1 min/month) is required over full temperature range | Select DS17887-5 when eliminating crystal layout sensitivity and reducing BOM count outweighs flexibility of discrete crystal selection |
| PCF8583P | I²C interface (vs. parallel bus), 256-byte NV RAM, no extended RAM or PWR/KS power-control logic - simpler interface but fewer system-control features | Preferred in low-pin-count designs where I²C is already present and advanced wake-up sequencing is unnecessary | Choose PCF8583P only when migrating from legacy I²C-based RTCs and system-level power control is handled externally |
Compared with DS17885E-5, DS17887-5 trades PCB design flexibility for guaranteed accuracy and reduced component count, while PCF8583P sacrifices parallel-bus performance and integrated power control for interface simplicity - neither offers the 8kB extended SRAM or software-controllable PWR output central to DS17885E-5's system-level role.
Availability
DS17885E-5 is available at Aetrix Electronics and suitable for utility metering, security systems, network infrastructure, and industrial HMI applications requiring stable component supply, long-term lifecycle support, and guaranteed battery-backed timekeeping.
Supply support for DS17885E-5 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and digital ICs for industrial, communications, and computing applications - with emphasis on reliability, low power, and integration.
The DS17885E-5 belongs to Maxim's legacy real-time clock family, engineered specifically for embedded systems needing autonomous timekeeping, nonvolatile data retention, and hardware-assisted power management during primary supply interruptions.
FAQ
What voltage ranges does the DS17885E-5 support?
The DS17885E-5 operates across two distinct supply ranges: +2.7V to +3.7V for 3V systems and +4.5V to +5.5V for 5V systems. Both VCC and backup supplies (VBAT, VBAUX) must remain within their respective specified limits. The DS17885E-5 does not support intermediate voltages like 3.3V directly - operation at 3.3V requires validation against the 3V spec limits, and margin analysis is recommended for robust design.
How much nonvolatile memory does the DS17885E-5 provide?
The DS17885E-5 provides 114 bytes of general-purpose battery-backed NV SRAM plus 8192 bytes of extended NV SRAM - totaling 8306 bytes. This memory remains fully retained during VCC loss when powered by VBAT or VBAUX. The extended SRAM is accessed via bank-switched addressing (Bank 1), and all memory is write-protected when VCC falls below the power-fail threshold (VPF).
Does the DS17885E-5 include an integrated crystal or battery?
No, the DS17885E-5 does not integrate a crystal or battery. It requires an external 32.768kHz crystal connected to X1/X2 pins and a separate lithium coin cell connected to VBAT. In contrast, the pin-compatible DS17887-5 variant integrates both crystal and battery in a 24-pin EDIP package. The DS17885E-5's SOIC-28 package retains full flexibility for crystal selection and backup supply architecture.
What is the function of the PWR and KS pins on the DS17885E-5?
The PWR pin is an active-low open-drain output used to control external power supplies, enabling full-system wake-up from RTC alarm or KS input. The KS (Kickstart) pin is an active-low input that triggers PWR assertion when VCC is absent - typically driven by a mechanical switch or keypad scan line. Both pins require proper VBAUX biasing and software configuration of the auxiliary-battery-enable (ABE) bit to function.
Can the DS17885E-5 generate a 1Hz square-wave output?
Yes, the DS17885E-5 can generate a precise 1Hz square-wave output on the SQW pin. This is achieved by setting the appropriate rate-select bits (RS0–RS3) in Register A to "0010", which configures the internal 15-stage divider to divide the 32.768kHz oscillator by 32768. The SQW output remains active even during VCC brownout if E32k=1 and VBAUX is present, making it suitable for watchdog or low-power timing tasks.
DS17885E-5 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Bag
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output
- Memory Size:
- 8KB
- Time Format:
- HH:MM:SS (12/24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- Parallel
- Voltage - Supply:
- 4.5V ~ 5.5V
- Voltage - Supply, Battery:
- 2.5V ~ 3.7V
- Current - Timekeeping (Max):
- 3mA @ 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 28-TSOP
DS17885E-5 FAQ
1.How can I place an order for DS17885E-5 through Aetrix?
Please submit a Request for Quotation (RFQ) for DS17885E-5 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for DS17885E-5 reliable?
The price and inventory of DS17885E-5 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS17885E-5 is usually 5 days.
3.What payment methods are accepted for DS17885E-5?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS17885E-5 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS17885E-5?
DS17885E-5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS17885E-5 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for DS17885E-5?
For technical support, including DS17885E-5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS17885E-5 requirements.
6.How does Aetrix verify that DS17885E-5 is sourced from the original manufacturer or authorized distributors?
All DS17885E-5 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that DS17885E-5 meets industry standards.
7.What is the process for return or replacement of DS17885E-5?
All DS17885E-5 units undergo pre-shipment inspection (PSI). If there is an issue with DS17885E-5, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The DS17885E-5 part is unused and in its original packaging.
Return procedure for DS17885E-5:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
DS17885E-5 Tags
-
MCP7940N-I/SN
Microchip Technology
-
MCP7940MT-I/MNY
Microchip Technology
-
PCF85063ATL/1,118
NXP USA Inc.
-
MCP7940NT-I/SN
Microchip Technology
-
MCP7940NT-I/MS
Microchip Technology
-
MCP7940N-I/MS
Microchip Technology
-
PCF85063AT/AY
NXP USA Inc.
-
PCF85063TP/1Z
NXP Semiconductors
-
PCF85063ATT/AJ
NXP USA Inc.
-
MCP7940NT-E/SN
Microchip Technology
-
MCP7940NT-I/MNY
Microchip Technology
-
MCP79400T-I/SN
Microchip Technology
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