DS31408GN+ - 8-Input 14-Output Dual DPLL Timing IC | Microchip
MPN: DS31408GN+ ✓ NakahandaDS31408GN+ Ulas
A DPLL (Digital Phase-Locked Loop) timing IC is a high-precision frequency synthesis and jitter-cleaning device used in telecom, Ethernet, and synchronization networks. Within the system hierarchy, a DPLL belongs to the timing IC family, which sits under clock generation, clock distribution, and clock & timing integrated circuits - a critical category in power management and signal chain design where reference clocks, PTP (Precision Time Protocol), and Stratum-compliant timing are required for carrier-grade equipment.
Key features of the DS31408GN+ include: a dual DPLL architecture with independent holdover and reference switching, support for Ethernet, SONET/SDH, Stratum 2/3E, and telecom line rates, sub-picosecond output jitter performance, integrated IEEE 1588 hardware support for PTP timestamping, and CMOS/TTL compatible I/O. The device includes on-chip EEPROM for autonomous configuration and supports SPI/I2C host interfaces for in-system programmability.
The DS31408GN+ integrates two independent DPLLs, each capable of locking to any of the 8 input references, with programmable bandwidth and fast-lock algorithms that minimize wander during reference switching. Its fractional-N output dividers support virtually any output frequency between 2 kHz and 750 MHz, eliminating the need for multiple discrete timing ICs in multi-protocol line cards.
Typical applications include SONET/SDH line cards, Ethernet switches and routers requiring SyncE or PTP synchronization, OTN (Optical Transport Network) equipment, base station synchronization, and Stratum-compliant timing subsystems in carrier-grade infrastructure. The dual-DPLL architecture is particularly valuable in equipment that must hold frequency during a primary reference failure.
When designing with this device, provide a low-jitter crystal or TCXO reference at the primary input and observe PCB layout guidelines for mixed-signal clock circuits - keep output traces impedance-controlled and length-matched, and decouple each supply pin with 0.1 uF ceramic capacitors placed as close as possible to the BGA balls. The 256-pin BGA package requires careful fanout and via-in-pad PCB technology for reliable assembly.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, helping timing engineers select the right configuration of the DS31408 platform for their application.
Mga alternatibo na pwedeng ilagay na DS31408GN+ — parehas na package, pin-to-pin na katugmang. Hindi kasama ang mga bahagi ng iba't-ibang package na nangangailangan ng pagpapaayos ng PCB.
DS31400GN+
✅ Drop-In📋 Alternatibo na Reference (hindi sa katalogo)
DS31406GN+
✅ Drop-In📋 Alternatibo na Reference (hindi sa katalogo)
DS31408GN+ Mga Spesipikasyon
| Fungsi | Clock/Frequency Synthesizer with Jitter Cleaner |
| Number of DPLLs | 2 (Dual DPLL) |
| Number of Input Clocks | 8 |
| Number of Output Clocks | 14 |
| Input Frequency Range | 2 kHz to 750 MHz |
| Output Frequency Range | 2 kHz to 750 MHz |
| Output Jitter | Sub-ps (typical) |
| PLL | Yes (Dual DPLL) |
| Main Purpose | Ethernet, SONET/SDH, Stratum, Telecom |
| Input Compatibility | CMOS, TTL |
| 1588 PTP Support | Yes (integrated hardware) |
| Host Interface | SPI / I2C |
| On-chip EEPROM | Yes (autonomous configuration) |
| Package Type | 256-CSBGA (17x17 mm) |
| Operating Temperature Grade | Industrial |
| Terminal Form | Ball |
| Uri ng Pagpapasok | Surface Mount |
| Tindminan RoHS | Compliant |
Gabay sa Pin Configuration ng DS31408GN+ 256-csbga (17x17 mm)
Pin configuration para sa DS31408GN+ (256-csbga (17x17 mm) package). Ang pagnunumero ng pin, mga function, at connection diagram ay tinukoy sa datasheet ng manufacturer. Sumangguni dito para sa eksaktong footprint at mga alituntunin sa soldering.
Wala ng detalyadong pinout data na magagamit para sa DS31408GN+.
Sumangguni sa datasheet para sa buong pin configuration.
Tipikal na mga Gamit
DS31408GN+ ay nararapat para sa 7 aplikasyons: SONET/SDH Line Card Synchronization, Ethernet Switch / Router SyncE and PTP, OTN Optical Transport Equipment, Wireless Base Station Synchronization, Stratum-2/3E Network Timing Subsystems, Test and Measurement Equipment, Industrial Timing and Control Systems.
SONET/SDH Line Card Synchronization
The DS31408GN+ is purpose-built for SONET/SDH line cards, where it derives all required transport frequencies from a primary Stratum reference while meeting G.813 Option 1/2 jitter and wander masks. Its dual-DPLL architecture provides automatic holdover during primary-reference failures, and the sub-ps output jitter eliminates tributary wander that would otherwise degrade long-haul payload integrity. With 14 independently-programmable outputs (2 kHz to 750 MHz), a single DS31408GN+ replaces the legacy multi-PLL BOM found in OC-192 line cards, and the integrated CMOS/TTL I/O interfaces directly to the framer ASIC without external level translation.
Inirekomenda
Ethernet Switch / Router SyncE and PTP
In SyncE-equipped Ethernet switches and routers, the DS31408GN+ provides the G.8262 EEC (Ethernet Equipment Clock) function with sub-ps output jitter and the integrated IEEE 1588 hardware timestamping for PTP grandmaster or boundary-clock operation. The 8 input clocks accept any combination of PTP references, GPS-disciplined clocks, or SyncE recovered clocks; the dual-DPLL can lock to one while filtering the other, and the 14 outputs feed each line-card PHY or ASIC with a clean, low-jitter reference. This makes the DS31408GN+ a one-chip timing solution for carrier-grade Ethernet switches, eliminating the need for an external TCXO + dedicated PHY clock tree.
Inirekomenda
OTN Optical Transport Equipment
OTN (Optical Transport Network) equipment requires precise multi-rate clock generation for OTU1/OTU2/OTU3/OTU4 payloads, all of which the DS31408GN+ can derive from a single reference through its fractional-N output dividers. The dual-DPLL enables simultaneous support of OTN's primary OTU clock and the secondary client-rate clock (e.g., 10G LAN PHY) with sub-ps jitter performance. This eliminates the need for multiple discrete frequency synthesizers on the OTN line card, simplifying BOM and reducing board area while improving holdover behavior during reference switching events.
Inirekomenda
Wireless Base Station Synchronization
In LTE, 5G NR, and small-cell base stations, the DS31408GN+ generates the radio-frequency clocks required for CPRI/eCPRI fronthaul links and baseband processing. Its 1588 PTP hardware timestamping is essential for TDD synchronization between radio units, where phase alignment between sectors must remain within sub-microsecond budgets. The 14 outputs support multiple radio chains, GPS-disciplined references, and backhaul interfaces from a single timing IC, while the dual-DPLL provides holdover during GPS loss-of-sky - a critical capability for macro-cell reliability.
Inirekomenda
Stratum-2/3E Network Timing Subsystems
Stratum-2 and Stratum-3E timing subsystems in carrier-grade equipment use the DS31408GN+ as the central DPLL element because of its programmable bandwidth and compliant wander/jitter generation per GR-1244-CORE. The dual-DPLL architecture supports primary and secondary reference inputs with automatic selection and hitless reference switching, maintaining output frequency even when both references fail (deep holdover). Industrial-grade operating temperature and on-chip EEPROM for autonomous configuration make the DS31408GN+ a drop-in timing engine for compliant timing subsystems.
Inirekomenda
Test and Measurement Equipment
Test and measurement instruments requiring ultra-low-jitter reference clocks (signal analyzers, frequency counters, jitter analyzers) use the DS31408GN+ as the master timing reference, where its sub-ps output jitter sets the noise floor of the instrument. The 14 programmable outputs feed the LO synthesizers, ADC sample clocks, and trigger systems of the instrument from a single, phase-coherent source, eliminating channel-to-channel skew. The on-chip EEPROM allows the instrument manufacturer to ship pre-calibrated timing configurations with no host processor intervention on power-up.
Inirekomenda
Industrial Timing and Control Systems
Industrial automation networks requiring IEEE 1588 grandmaster timing (e.g., process control, substation automation per IEC 61850) use the DS31408GN+ to distribute sub-microsecond synchronized clocks across the plant. The dual-DPLL supports both PTP grandmaster mode and slave-clock recovery with sub-ps output jitter, enabling tight synchronization of distributed I/O. The industrial operating temperature grade and CMOS/TTL I/O simplify interface to industrial Ethernet PHYs and FPGA-based controllers, while the on-chip EEPROM allows standalone operation without a host microcontroller.
Inirekomenda
Buod ng mga Inirekomendang Produkto
Impormasyon ng Talumpati sa Engineering for DS31408GN+ — ikabit, gabay sa disenyo, at impormasyon ng pagsunod sa kautusan.
Paunawang Hanapin
Ikabit sa Mga Alternatibo
| Parametro | Ito ang Producto | DS31400GN+ | DS31406GN+ |
|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 256-CSBGA (17x17 mm) | 256-CSBGA (17x17 mm) - same | 256-CSBGA (17x17 mm) - same |
| Number of DPLLs | 2 (Dual DPLL) | 1 (Single DPLL) | 2 (Dual DPLL) |
| Input Clocks | 8 | 6 | 8 |
| Output Clocks | 14 | 12 | 12 |
| 1588 PTP Hardware | Yes (integrated) | No | No |
| Input Frequency Range | 2 kHz to 750 MHz | 2 kHz to 750 MHz | 2 kHz to 750 MHz |
| Output Frequency Range | 2 kHz to 750 MHz | 2 kHz to 750 MHz | 2 kHz to 750 MHz |
| Holdover Support | Yes (DPLL 1 + DPLL 2) | Limited (single DPLL) | Yes (Dual DPLL) |
Pangunahing mga Pagkakaiba
- Dual DPLL with sub-ps output jitter (kumpara saDS31400GN+)
- Integrated IEEE 1588 hardware timestamping (kumpara saDS31406GN+)
- 14 output clocks (vs 12 on alternatives) (kumpara saDS31400GN+)
- One-chip SyncE + PTP solution (kumpara saCross-brand TI LMK04832)
Talaan ng Disenyo
The 256-CSBGA package requires via-in-pad (VIP) PCB technology with 0.5 mm pitch microvia fanout. Use a 4-layer PCB minimum with continuous ground plane under the IC; route differential output pairs (e.g., for SyncE) with 100 ohm differential impedance and length-match within 1 mm across each output pair. Decouple each VDD ball with a 0.1 uF X7R ceramic placed within 100 mil of the via, and add a single 10 uF bulk capacitor per supply domain. Without proper via-in-pad and ground-plane design, BGA-joint reliability and EMI performance both degrade.
Power the DS31408GN+ from a low-noise LDO (such as TPS7A4701) rather than the upstream switching converter directly. While the device has internal power conditioning, sub-ps jitter performance is degraded when supply noise above 100 kHz couples into the VCO; keep the LDO within 25 mm of the BGA and star-route each supply domain. Estimated: at full operation across all 14 outputs the device draws roughly 800 mA from the 1.8 V core supply - verify the LDO can sustain this with adequate thermal margin.
Do not assume the on-chip EEPROM is shipped with the correct configuration for your application - Microchip ships the part blank or with default Stratum settings. Always program the device via SPI/I2C at first power-up using the device's evaluation software, then save the working configuration to EEPROM. A common pitfall is forgetting to set the DPLL bandwidth, which defaults to a wide value unsuitable for Stratum wander filtering; the result is excessive output jitter and ITU-T G.813 wander mask failures. Allow at least 1 second of settling time after DPLL bandwidth changes before re-measuring jitter.
Estimated: with all 14 outputs active at 750 MHz CMOS switching into 50 ohm loads, total device dissipation is approximately 1.4 W. The 256-CSBGA thermal resistance (theta_JA) is roughly 22 C/W on a 4-layer JEDEC test board, yielding a 31 C junction rise above ambient - well within the industrial 85 C operating limit. However, in enclosed chassis without airflow, add copper flooding under the BGA or a small heat spreader. Always verify with a thermal probe in the final mechanical enclosure, not on the bench.
Keep high-speed CMOS clock outputs on the top PCB layer only and avoid layer transitions; each via adds ~1 pF of parasitic capacitance that can degrade the rising edge into 750 MHz signals, contributing to output jitter. If routing on inner layers is unavoidable, use back-drilled vias to remove the unused stub. Series-terminate each CMOS output with a 33 ohm resistor placed within 200 mil of the BGA ball, and AC-couple or DC-couple according to the receiver's requirements - never leave a long unterminated trace.
Impormasyon ng Pagsunod sa Kautusan
RoHS and lead-free per Microchip product page. Industrial temperature grade (not automotive AEC-Q100). Halogen-free status not explicitly stated in retrieved data - confirm with Microchip datasheet if required.
