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Accordion 8-ch Current Source Module

ESH10000584 · Rev R1

electronicsin_progress

Generated 2026-07-26 13:59 UTC

Accordion N-Module 8-channel current source — R1. Drives the 8 LED current outputs (0–450 mA). Sub-assembly of the Collimator LED Control Box (ESH10000672 R1).

Lightweight shell — full new_project workflow pending. Imported as a dependency of ESH10000672 R1.

Coverage 0%

Done 0%

Requirements 0

Test Cases 0

Records 0

Milestones

Code	Title	Status	Target	Achieved	TC
MS-001	Tape-out (PCB to JLC)	marker	2026-07-03	—	0 / 0
MS-002	Bring-up	marker	2026-08-28	—	0 / 0

Milestone gates

Items (3)

Code	Status	Severity	Kind	Title	Date
E-001	open	warning	notice	ESH10000584 is an established N-Top current-source product, newly imported into Trace	2026-06-23
E-002	open	warning	notice	Open spec gaps on ESH10000584 — quantify before approval	2026-06-23
E-003	open	info	decision	584 control/measurement topology: external DAC set-point + INA2181A1 sense → external ADC (depends on ESH10000590)	2026-06-23

Requirements

Code	Status	Category	Title	Statement	Acceptance
REQ-001	draft	Mechanical	Accordion N-Top module form factor	The module shall be implemented as an Accordion N-Top form-factor module, compatible with the Accordion M1 mainboard (ESH10000597) N-Top interface.	Module mates mechanically and electrically with the Accordion M1 N-Top connector; pinout conforms to the N-Top interface contract.
REQ-002	draft	Functional	8 independently controllable current-source channels	The module shall provide 8 current-source output channels, each with individual current control.	All 8 channels can be set and held to independent output currents without cross-interference.
REQ-003	draft	Performance	Per-channel output current range 0–500 mA	Each channel shall source output current over the range 0–500 mA.	Set-point sweep 0–500 mA on each channel; measured output current reaches full scale and 0 without clipping or instability.
REQ-004	draft	Functional	0–5 V control reference (linear) maps to 0–500 mA output	Each channel's output current shall be controlled by a 0–5 V reference/control voltage with a linear transfer function: 0 V → 0 mA, 5 V → 500 mA. The control voltage is supplied by an external DAC — the module has no on-board DAC (see REQ-010).	Apply control voltage across 0–5 V; output current tracks the linear 0–500 mA mapping. Set-point digital resolution/accuracy is governed by the external DAC; the module's V→I conversion tolerance is TBD.
REQ-005	draft	Performance	Per-channel current sense via INA2181A1 across 500 mΩ shunt (external ADC)	Each channel shall sense its output current using an INA2181A1 current-sense amplifier (gain 20 V/V) across a 500 mΩ shunt. The amplified analog output is digitized by an external ADC — the module has no on-board ADC (see REQ-010). Full scale: 500 mΩ × 500 mA × 20 V/V = 5 V.	Each channel's sensed output (via INA2181A1) tracks actual output current across 0–500 mA. Measurement accuracy is bounded by the INA2181A1 (gain error + offset) plus the external ADC resolution. TBD — final accuracy figure from the INA2181A1 datasheet error budget.
REQ-006	draft	Performance	Off-state channel leakage < 1 µA	When a channel is commanded off, its output leakage current shall be less than 1 µA. (Critical requirement.)	With a channel off, measured output current < 1 µA across the operating range/conditions of the other (active) channels.
REQ-007	draft	Environmental	Thermal limit ≤ 50 °C under all conditions	The module shall remain below 50 °C under all operating conditions, including full load (8 × 500 mA simultaneously).	Full-load soak (8 × 500 mA); all measured module temperatures ≤ 50 °C. TBD — confirm the ambient reference condition.
REQ-008	draft	Functional	Two auxiliary ADC monitoring channels (single-ended + differential)	The module shall provide two additional channels routed to ADC inputs for external monitoring, supporting both ground-referenced (single-ended) and differential measurement.	Both aux channels accept an external signal and return a valid ADC reading in single-ended (ground-referenced) and differential modes. TBD — confirm input voltage range and accuracy.
REQ-009	draft	Performance	5 V input rail droop ≤ 1% under load	The 5 V input shall not dip by more than 1% under any load condition, including full load (8 × 500 mA).	Measure 5 V input under full load; droop from nominal ≤ 1% (≤ 50 mV). TBD — confirm whether "5 V input" is the supply rail or the control reference.
REQ-010	draft	Interface	No on-board ADC/DAC — analog interface to external ADC/DAC module	The module shall contain no on-board ADC or DAC. Channel set-point control (analog voltage in) and current-sense / aux monitoring (analog voltage out) interface to an external ADC/DAC module — the Accordion Precision ADC/DAC Module, ESH10000590.	Schematic/BOM confirm no ADC/DAC on the module; all set-point and readback signals are analog at the module connector and resolved by ESH10000590.

Test Cases

No test cases recorded.

Verification Records

No verification records.

Decisions

E-003 584 control/measurement topology: external DAC set-point + INA2181A1 sense → external ADC (depends on ESH10000590) info 2026-06-23

Decision

ESH10000584 is a pure analog V→I current-source module with no on-board ADC/DAC. It depends on an external ADC/DAC module (ESH10000590, Accordion Precision ADC/DAC) for both directions:

Set-point (in): external DAC produces a 0–5 V control voltage per channel → linear 0–500 mA output.
Readback (out): per-channel INA2181A1 current-sense amplifier (gain 20 V/V) across a 500 mΩ shunt → analog output → external ADC.
Aux (out): 2 extra channels route analog signals to external ADC inputs (single-ended + differential).

Full-scale check

500 mΩ × 500 mA × 20 V/V = 5 V at the INA2181A1 output → matches a 0–5 V external ADC range. Consistent with the 0–5 V control side.

Consequence

Measurement accuracy is throttled by the INA2181A1 (gain error + offset), not by this module's shunt alone.
Creates a hard interface contract between ESH10000584 and ESH10000590 — the analog set/sense lines must match across the N-Top/stack interface. Capture as a formal interface when both module pinouts are confirmed.

Notices

E-001 ESH10000584 is an established N-Top current-source product, newly imported into Trace warning open 2026-06-23

ESH10000584 (Accordion 8-ch Current Source Module) is based on an established product that was never previously tracked in Trace. REQ-001…008 (Draft) were reconstructed from the engineer's verbal description on 2026-06-23 — not yet validated against the authoritative schematic/BOM/design docs. Confirm each requirement against the real design before approving. Drives the 8 LED current outputs of the Collimator LED Control Box (ESH10000672 R1).

E-002 Open spec gaps on ESH10000584 — quantify before approval warning open 2026-06-23

Updated 2026-06-23 after engineer input.

RESOLVED:

REQ-004 — transfer function confirmed linear (0–5 V → 0–500 mA); set-point from external DAC.
REQ-007 — thermal confirmed ≤ 50 °C under all conditions.
Topology clarified: no on-board ADC/DAC → added REQ-010; current sense via INA2181A1 (REQ-005); 5 V droop ≤ 1% → added REQ-009. See decision entry on this project.

STILL OPEN (quantify before approval / verification planning):

REQ-005 — per-channel current-measurement accuracy: dominant term is the INA2181A1 (gain 20 V/V) gain error + offset; need the final ±accuracy figure from the datasheet error budget + external ADC resolution.
REQ-008 — aux ADC monitoring channels: input voltage range and accuracy.
REQ-004 — module V→I conversion tolerance (analog conversion error, separate from external DAC resolution).
REQ-009 — confirm whether "5 V input" is the supply rail or the control reference; confirm nominal + conditions.

Note: module range 0–500 mA (REQ-003) vs unit 0–450 mA (ESH10000672 REQ-002) — module headroom, expected.

Design Rule Status

■ No violations ■ Warning ■ Error ■ Waived