1) Bluetooth Antenna Keep-out Zone: - Reserve at least a 15 mm clearance (no copper pour, no traces, no vias, no components) directly under and around the antenna portion of the Bluetooth module, extending in the main radiation direction toward the board edge. - Do not route high-speed, high-current, or clock traces beneath or immediately adjacent to the antenna area on any layer. - Maintain continuous, unbroken ground plane around (but not under) the antenna region to provide a stable RF reference; use a ground cut-out directly under the antenna as per module datasheet. - Keep metal objects, mounting holes, and shields outside the antenna keep-out outline. 2) Functional Partitions and Boundaries: - Define three primary PCB regions: (A) Analog Measurement Section (cuff pressure sensing, ADC front-end, transducer excitation), (B) Digital Section (MCU, Bluetooth, memory, digital interfaces), and (C) Power Section (AC/DC adapter input, DC/DC/switching regulators, pump/valve drivers). - Place the analog section farthest from the pump/valve drivers and switching regulators; place the Bluetooth module near a board edge for optimal RF performance and away from high-current loops. - Mark partition boundaries with silkscreen or mechanical layer outlines: "ANALOG", "DIGITAL", and "POWER". 3) Ground / Return-Path Segregation: - Use separate copper regions for AGND (analog ground), DGND (digital ground), and PGND (power/switching return) with a single-point star connection near the ADC/microcontroller ground reference. - Keep analog signal return paths confined to the AGND area, routed directly back to the star point without crossing digital or power current loops. - Keep high di/dt switching currents (DC/DC converter loops, pump/valve drivers) confined to the PGND region with tight, local loops and minimal loop area. - Do not route sensitive analog traces across splits in the ground plane; ensure continuous AGND plane directly beneath all low-level analog measurement traces. - If guard traces are used around high-impedance analog nodes, connect them to AGND only and keep them isolated from DGND/PGND. 4) Partition Crossing Rules: - Route analog-to-digital interface signals (e.g., ADC outputs, sensor SPI/I2C) across partition boundaries only at controlled, narrow corridors where AGND and DGND planes are joined at the star point. - Use series resistors and RC filters on boundary-crossing lines to reduce digital noise coupling into the analog domain. - Keep power supply transitions (e.g., from DC/DC outputs to analog LDO regulators) localized at the edge of the power and analog regions; place LDOs and filter components at the boundary to improve isolation. 5) EMC/EMI and Safety Considerations: - Maintain clear separation between mains-referenced circuitry in the external adapter and SELV, patient-connected circuitry on this PCB; no mains routing onto the medical PCB. - Orient digital and power return paths so that their loop areas do not overlap the Bluetooth antenna keep-out or the sensitive analog measurement region. - Reserve a continuous chassis/earth or shield reference area (if used) away from the antenna and analog front-end, with defined connection points to the system ground for controlled EMI behavior. 6) RF_50OHM Antenna Keep-out and Ground Stitching Corridor: - Maintain the existing antenna keep-out region for all RF_50OHM net routing: no copper pour, no non-RF traces, no vias, and no components within the defined antenna clearance area except those explicitly part of the RF matching network. - Ensure that RF_50OHM traces within the antenna region reference a continuous ground via a controlled stitching-via corridor located adjacent to (but not inside) the antenna no-copper zone. - Place ground stitching vias at a regular pitch (≤ 1/20 of the RF wavelength in FR-4 at the operating Bluetooth frequency) along the corridor to maintain a stable RF return and to confine RF currents near the RF_50OHM trace. - Do not interrupt the stitching-via corridor with splits in the ground plane, cutouts, or large signal/power vias; reroute non-RF nets to avoid breaking the RF reference ground path. - Keep any shields, metal enclosures, or large ground fills outside the defined antenna keep-out and ensure they connect via the stitching corridor so as not to detune the antenna. - Document the antenna keep-out outline and ground stitching corridor on a dedicated mechanical or keep-out layer, and lock these constraints so they are preserved across layout revisions. 7) Analog Measurement Front-end Annotation: - Near the pressure-sensing analog front-end placeholder, all ANALOG_MEAS nodes and traces must be clearly tagged and routed entirely within the analog partition. - ANALOG_MEAS traces must be routed in the analog partition over unbroken AGND (continuous analog ground plane), with no crossings over ground splits or returns from digital or power domains. - Maintain short, direct routes from the pressure transducer and front-end amplifier/ADC inputs to minimize loop area and noise pickup. - Any transition from ANALOG_MEAS to other domains must occur only at the defined analog boundary component (L1) and through the controlled analog-to-digital interface corridor at the star ground point.

True

width 2.8 mm; clearance 6 mil; routing within the antenna keep-out area with reference to ground stitching via placement

Isolation

True

width 8 mil; clearance 8 mil; routing applied downstream of D2 and D3 and at J1

Radiated, conducted, EFT on DC, dips on DC

ESD: ±8 kV contact, ±15 kV air; RF immunity: radiated, conducted, EFT on DC, dips on DC; isolation requirements for non-medical external ports.

True

LCSC

Home-use device classification

Mains

40 mil

Medical

width 6 mil; clearance 6 mil; traces must be routed in the analog partition over unbroken ground; boundary limited by L1

±8 kV contact, ±15 kV air

Nets will be assigned later based on placeholder component tags (e.g., IO_ESD, ANALOG_MEAS, RF_50OHM, POWER_SWITCH) and the documented net class rules for width/clearance and partition boundaries. Current properties and annotations act as a scaffold for future net naming and connectivity once the full schematic is implemented.

Analog

Isolation requirements for non-medical external ports (non-patient, non-mains).

Medical-grade SELV adapter requirement for BF-classified, home-use BP monitor; external adapter must be BIS-registered and provide SELV-limited output for patient-connected circuitry.

12 mil

RoHS

1.6 mm

width 10 mil; clearance 10 mil; domain: Power Switching

VIN, VIN_FILT