DS1501WEN+ - Y2K-Compliant Watchdog RTC, 256B NV SRAM | Maxim
N.º da peça: DS1501WEN+ ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $8.45 | $8,45 |
| 10 | $7.62 | $76,20 |
| 100 | $6.75 | $675,00 |
| 500 | $6.1 | $3.050,00 |
| 1.000 | $5.45 | $5.450,00 |
DS1501WEN+ Visão geral
What is an RTC? A Real-Time Clock (RTC) is a dedicated timekeeping integrated circuit that maintains accurate wall-clock time (seconds, minutes, hours, day, date, month, year, century) even when the host system is powered down, typically by backup battery or supercapacitor. RTCs belong to the broader family of clock/calendar ICs, which sit under the timing & application category and ultimately under the power management / system supervision domain. RTCs differ from MCU-internal timers in that they run independently of the host CPU and continue counting through power loss.
Key features of the DS1501WEN+ include Y2K-compliant century register, integrated watchdog timer for host firmware supervision, power-on reset and battery monitor circuits, 256 bytes of non-volatile SRAM that retains data through battery backup, and a buffered 32.768 kHz output for downstream clock distribution. The parallel bus allows byte-wide register access for fast data reads/writes.
Internally, the DS1501 uses a low-power CMOS oscillator driving a chain of BCD-coded registers (century, year, month, date, day, hours, minutes, seconds). The on-chip NV SRAM is automatically switched to backup battery when VCC falls below a programmable threshold, and the device asserts RST on power-up to safely initialize the host CPU. The watchdog can be programmed to reset the host if a strobe is not received within a defined window.
Typical applications include embedded industrial controllers requiring time-stamped event logging, point-of-sale (POS) terminals, secure access controllers, medical instruments with battery-backed timekeeping, and server/workstation BIOS clock replacement. The wide temperature range and integrated supervisory functions make it suitable for harsh environments.
When designing with this device, ensure VBAT is connected to a backup lithium coin cell or supercapacitor through the recommended decoupling network; verify that the host's parallel bus timing matches the DS1501 access specifications. The XAIPART datasheet documents detailed read/write timing diagrams and battery switchover thresholds. This product page synthesizes distributor pricing, drop-in alternatives, and practical design notes that go beyond the manufacturer datasheet.
Alternativas drop-in para DS1501WEN+ — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
DS1501WE+
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
DS1501WEN+T&R
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
DS1501WS+
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
DS1501WN+
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
M48T86PC1
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
DS1338Z-33+
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
DS1501WEN+ Especificações
| Função | Real-Time Clock (RTC) with alarm, watchdog, NV SRAM |
| Tamanho da memória | 256 bytes NV SRAM |
| Date Format | YY-MM-DD (Y2K-compliant with century register) |
| Time Format | HH:MM:SS (BCD) |
| Interface | Parallel (byte-wide) |
| Supply Voltage (VCC) | 3.0 V to 3.6 V (3.3 V typ) |
| Battery Supply (VBAT) | 2.5 V to 3.7 V (typ coin cell) |
| Oscillator Frequency | 32.768 kHz |
| Programmable Alarms | Day-of-week / date / time |
| Watchdog Timer | Yes (programmable timeout) |
| Power-On Reset | Yes |
| Battery Monitor | Yes (switchover + low-battery flag) |
| Temperatura de operação | -40 C to +85 C |
| Encapsulamento | 28-TSSOP (11.80 mm width, 0.65 mm pitch) |
| Tipo de montagem | Surface Mount |
| Nível MSL | 1 |
| Status RoHS | Compliant |
| Lead-Free | Yes |
Configuração de pinos do DS1501WEN+
| Pino 1 | AD0 — Address/Data bus bit 0 |
| Pino 2 | AD1 — Address/Data bus bit 1 |
| Pino 3 | AD2 — Address/Data bus bit 2 |
| Pino 4 | AD3 — Address/Data bus bit 3 |
| Pino 5 | AD4 — Address/Data bus bit 4 |
| Pino 6 | AD5 — Address/Data bus bit 5 |
| Pino 7 | AD6 — Address/Data bus bit 6 |
| Pino 8 | AD7 — Address/Data bus bit 7 |
| Pino 9 | VCC — +3.3 V main supply |
| Pino 10 | GND — Ground |
| Pino 11 | X1 — 32.768 kHz crystal input |
| Pino 12 | X2 — 32.768 kHz crystal output |
| Pino 13 | /CS — Chip select (active low) |
| Pino 14 | /OE — Output enable (active low) |
| Pino 15 | /WE — Write enable (active low) |
| Pino 16 | /CE — Chip enable (active low) |
| Pino 17 | A0 — Address bus bit 0 |
| Pino 18 | A1 — Address bus bit 1 |
| Pino 19 | A2 — Address bus bit 2 |
| Pino 20 | A3 — Address bus bit 3 |
| Pino 21 | A4 — Address bus bit 4 |
| Pino 22 | /IRQ — Interrupt request (active low) |
| Pino 23 | RST — Reset output (active high) |
| Pino 24 | VBAT — Backup battery input |
| Pino 25 | NC — Not connected (per datasheet) |
| Pino 26 | 32K_OUT — 32.768 kHz buffered output |
| Pino 27 | NC — Not connected (per datasheet) |
| Pino 28 | NC — Not connected (per datasheet) |
Aplicações típicas
DS1501WEN+ é adequado para 7 aplicaçãos: Industrial Controller Timekeeping, Point-of-Sale (POS) Terminal, Medical Instrument Data Logging, Server BIOS Clock Replacement, Secure Access Controller, Automotive Telematics (Non-Safety Sub-System), Embedded System Time Stamping.
Industrial Controller Timekeeping
The DS1501WEN+ fits the industrial controller timekeeping application because its 3.0-3.6 V supply and 28-pin TSSOP interface match the standard 3.3 V MCU bus rails found in PLCs and factory automation controllers. Its Y2K-compliant century register and BCD-coded time registers enable reliable millisecond-accurate event logging across multi-decade deployments, while the watchdog timer supervises the host MCU and forces a reset on firmware lockup, a critical function for unattended industrial equipment. Placed on the MCU's parallel expansion bus, the device adds timestamp metadata to alarm and SCADA events without consuming the host's internal timer resources; it also preserves log data through power loss via its 256-byte NV SRAM backed by a lithium battery. Unlike a software RTC emulation, the DS1501 keeps time accurately across decades even when the host is unpowered, with standby current low enough that a 3 V coin cell sustains the part for 5-10 years.
Recomendado
Point-of-Sale (POS) Terminal
The DS1501WEN+ fits the POS terminal application because its parallel byte-wide interface enables fast bulk reads during receipt time-stamping and end-of-day reconciliation, where low latency between transaction and timestamp matters. Its integrated power-on reset and battery monitor functions ensure that date/time data survives power outages common in retail environments, preserving audit trails required by retail accounting compliance. Integrated onto the POS main board's 3.3 V logic rail, the DS1501 backs up to a coin cell, and its watchdog timer supervises the POS application processor to recover from software crashes by force-rebooting after a programmed interval, eliminating the need for a service manual reset visit. Unlike a network-time-protocol-only approach, the DS1501 keeps time during network disconnection and provides timestamps that match legally-traceable requirements independent of the cloud.
Recomendado
Medical Instrument Data Logging
The DS1501WEN+ fits medical instrument data logging because its industrial temperature rating of -40 C to +85 C covers clinical environment operating conditions, while its Y2K-compliant century register ensures unambiguous long-term timestamps required in clinical records retained for decades. The 256-byte NV SRAM allows the device to buffer the most recent patient readings across power cycles, preserving the last-known state when mains power is lost mid-procedure. Placed near the host processor's memory-mapped bus, the DS1501's /IRQ output drives an interrupt on alarm match for scheduled clinical events; its watchdog timer prevents firmware lockup that could endanger patient safety. The TSSOP package allows compact PCB layouts typical of handheld diagnostic devices, while the long battery-backup lifetime reduces field-service interruptions for medical installations.
Recomendado
Server BIOS Clock Replacement
The DS1501WEN+ fits server BIOS clock replacement because its parallel interface matches the legacy ISA-bus-style connections found in server motherboards, while its battery-backed NV SRAM retains BIOS configuration settings through power loss, supporting server boot across cold restarts. The integrated 32.768 kHz output drives downstream system clock distribution, eliminating the need for a separate crystal oscillator module. Placed on the Super I/O companion chip's parallel bus, the DS1501 provides the BIOS clock and CMOS RAM functions historically implemented by Dallas Semiconductor parts; the part's industrial temperature rating supports data-center operating conditions including rack-mount ambient temperatures. Engineers should verify that the Super I/O chip supports the DS1501 register map or includes a port-mapping register file.
Recomendado
Secure Access Controller
The DS1501WEN+ fits secure access controller designs because its integrated watchdog timer supervises the access-controller firmware against lockup, while the Y2K-compliant RTC provides tamper-evident audit-log timestamps required for regulatory compliance (e.g., audit-trail logging). The 256-byte NV SRAM holds recent access events across power cycles, while the alarm function triggers scheduled access-window events. Placed on the access controller's 3.3 V logic rail, the DS1501 issues /IRQ to wake the host MCU on alarm match and resets the host on watchdog timeout, eliminating a separate supervisor IC. The wide operating temperature range and industrial-grade NV SRAM retention make the part suitable for outdoor access-control installations in security-cabinet enclosures.
Recomendado
Automotive Telematics (Non-Safety Sub-System)
The DS1501WEN+ fits non-safety automotive telematics sub-systems (e.g., fleet-management data loggers, GPS timestamp references) where the wide -40 C to +85 C industrial temperature range covers cabin-environment operation. Its parallel interface provides fast bulk timestamp reads when bulk-writing GPS track logs to non-volatile storage. Placed on the telematics unit's 3.3 V logic rail, the DS1501 maintains time accuracy through vehicle battery disconnect events via coin-cell backup, while the watchdog timer supervises the telematics MCU. For full AEC-Q100 automotive qualification, designers should select a different Maxim/ADI RTC such as the MAX31334; the DS1501WEN+ is suitable only for non-safety sub-systems per the datasheet temperature grade.
Recomendado
Embedded System Time Stamping
The DS1501WEN+ fits generic embedded-system time-stamping because its parallel byte-wide interface allows the host MCU to read or write the time registers in a single bus cycle, critical when timestamping high-rate asynchronous events such as in networking switches, industrial sensors, or data-acquisition front ends. Its 256 bytes of NV SRAM buffer the most-recent timestamps across power loss, supporting event-log recovery after unexpected shutdowns. Placed on the host's memory bus, the DS1501's integrated watchdog supervises the host firmware; the device's wide temperature range supports industrial and outdoor installations. This is the broadest application category and the reason the DS1501 family has remained in production since the 1990s across many embedded designs.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para DS1501WEN+ — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | DS1501WE+ | DS1501WEN+T&R | DS1501WS+ | DS1501WN+ | M48T86PC1 | DS1338Z-33+ |
|---|---|---|---|---|---|---|---|
| Brand | Analog Devices (Maxim Integrated) | Analog Devices (Maxim Integrated) | Analog Devices (Maxim Integrated) | Analog Devices (Maxim Integrated) | Analog Devices (Maxim Integrated) | STMicroelectronics | Analog Devices (Maxim Integrated) |
| Package | 28-TSSOP | 28-TSSOP | 28-TSSOP | 28-TSSOP | 28-TSSOP | 28-SOIC | 8-SOIC |
| Supply Voltage | 3.0 V to 3.6 V | 3.0 V to 3.6 V | 3.0 V to 3.6 V | 3.0 V to 3.6 V | 3.0 V to 3.6 V | 4.5 V to 5.5 V | 3.0 V to 5.5 V |
| Interface | Parallel | Parallel | Parallel | Parallel | Parallel | Parallel | I2C |
| Watchdog Timer | Yes | Yes | Yes | Yes | Yes | Yes | No |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | 0 C to +70 C | -40 C to +85 C |
| 32.768 kHz Output | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| AEC-Q100 Qualified | No | No | No | No | No | No | No |
Principais diferenciais
- Integrated Y2K-compliant century register (vs M48T86PC1)
- Wide industrial temperature range with parallel interface (vs DS1338Z-33+)
- 256 bytes NV SRAM with battery backup (vs M48T86PC1)
Notas de projeto
The DS1501WEN+ requires a backup battery (VBAT) for timekeeping and NV SRAM retention through main power loss. Connect VBAT through a low-leakage Schottky diode to a 3 V lithium coin cell (e.g., CR2032 or BR2032); keep the diode reverse-leakage below 1 uA to maximize cell life. Place a 0.1 uF decoupling capacitor close to VCC and a 1 uF capacitor on VBAT per the Maxim reference schematic. Estimated backup lifetime at 25 C with 1.5 uA standby: approximately 5-8 years for a 220 mAh CR2032.
Place the 32.768 kHz crystal as close as possible to the X1 and X2 pins (within 5 mm) to minimize stray capacitance. Use a crystal with a load capacitance of 6-12 pF matching the DS1501's internal load capacitance specification. Route the crystal traces over a continuous ground plane and avoid routing digital signals (AD bus, /WE) under or adjacent to the crystal traces to prevent coupling into the time reference. Add 4-layer PCB with dedicated ground plane for best EMI immunity.
Do not exceed 3.6 V on VCC; the DS1501WEN+ is NOT 5 V tolerant. Apply the VCC supply only after VBAT is connected to avoid unintended battery current draw. Verify that the host parallel bus timing (CE, OE, WE pulse widths) meets the DS1501 datasheet AC specifications, especially t_AS address-setup and t_AH address-hold. Failure to program the watchdog timeout register (in the correct millisecond range) after generating may leave the watchdog in the previous chip state, an oversight. Always invoke DS1501X/NX firmware initialization per Maxim Application Note 122.
The parallel address/data bus is a shared-bus interface and can be a source of crosstalk in dense layouts. Place series damping resistors (22-47 ohm) on AD0-AD7 if the bus length exceeds 50 mm or if the bus operates above 10 MHz. Keep bus traces matched in length within 5 mm to avoid skew-induced timing errors. For designs where bus reflections appear on the 32K_OUT signal, add a 10-22 pF load capacitor or a series resistor to dampen ringing.
Informações de conformidade
RoHS compliant per Maxim product page. Lead-free matte-tin plating. Not AEC-Q100 qualified; not for safety-critical automotive applications. Halogen-free per JEDEC JS709A-class packaging. Conflict minerals compliant under Section 1502 of the Dodd-Frank Act.
