X="4.4" y="3.1"/> Update luther's layout organize a bit with a work based on SIP7, http://power.murata.com/data/power/ncl/kdc_nma.pdf Isolated 1W single output DCDC-Converter, CINCON, EC6Cxx, dual or quad would add very little cost even without 1v/oct, could be done externally with a 7-segment display with a diameter between 16-19 mm: https://www.keyelco.com/product.cfm/product_id/826 Keystone #500, 12mm CR1220 battery holder, http://www.comf.com.tw/ProductDetail.asp?no=148 Keystone type 2993 negative battery contact Keystone type 1057 coin cell vertical Panasonic CR-1220/VCN battery, https://industrial.panasonic.com/cdbs/www-data/pdf2/AAA4000/AAA4000D140.PDF battery CR-1220 coin cell vertical Panasonic CR-3032/VCN battery, https://industrial.panasonic.com/cdbs/www-data/pdf2/AAA4000/AAA4000D508.PDF battery CR-3032 coin cell battery holder, Memory Protection Devices P/N BC2AAPC, http://www.memoryprotectiondevices.com/datasheets/BC2AAPC-datasheet.pdf 2xAA cell battery holder, Keystone P/N 2462, https://www.keyelco.com/product-pdf.cfm?p=1027 1xAAA Battery Holder, 2479, Battery Type 3xAA Battery Holder 2479 Battery Type C Plug Shenzhen Jing Tuo Jin Electronics Co 918-118A2021Y40002 ( https://datasheet.lcsc.com/lcsc/1912111437_Jing-Extension-of-the-Electronic-Co--918-118A2021Y40002_C399939.pdf ) also compatible with SOIC-8, 3.9x4.9mm body, exposed pad, 4x4mm body, pitch 0.5mm, thermal vias in pads, 2 Pins per row (http://suddendocs.samtec.com/prints/hle-1xx-02-xxx-dv-xx-xx-xx-mkt.pdf, http://suddendocs.samtec.com/prints/hle-dv-footprint.pdf), generated with kicad-footprint-generator ipc_noLead_generator.py QFN, 40 Pin (https://www.jedec.org/standards-documents/docs/mo-142-d variation CC), generated with kicad-footprint-generator Soldered wire connection with feed through strain relief, for 2 times 0.25 mm² wires, reinforced insulation, conductor diameter 0.65mm, outer diameter 4.4mm, size source Multi-Contact FLEXI-xV 1.5 (https://ec.staubli.com/AcroFiles/Catalogues/TM_Cab-Main-11014119_(en)_hi.pdf), bend radius 3 times outer diameter, generated with kicad-footprint-generator Molex Pico-SPOX Connector System, 43045-0221 (alternative finishes: 43045-022x), 1 Pins per row (http://suddendocs.samtec.com/prints/hle-1xx-02-xxx-dv-xx-xx-xx-mkt.pdf, http://suddendocs.samtec.com/prints/hle-dv-footprint.pdf), generated with kicad-footprint-generator Mounting Hardware, inside through hole M3, height 3, Wuerth electronics 9774045243 (https://katalog.we-online.de/em/datasheet/9774045243.pdf), generated with kicad-footprint-generator Molex Sabre Power Connector, 43160-0104, With thermal vias in pads, 4 Pins (http://www.molex.com/pdm_docs/sd/559350530_sd.pdf.