Abstract: This application note explains how to program the DS1863/DS1865 PON controllers' integrated Bias DAC for manual mode. Introduction The DS1863 and DS1865 PON controllers integrate a 13-bit Bias DAC, which operates in either manual or automatic mode. This application note describes the procedure for programming the DAC in the manual mode. Controlling the BIAS DAC If the BIAS-EN bit (Table 02h, Register 80h) is written to 0, the BIAS DAC is manually controlled by the MAN IBIAS Register (Table 02h, Registers F8h–F9h). F8h Reserved Reserved 212 211 210 29 28 27 F9h 27 26 25 24 23 22 21 20   Bit 7             Bit 0 The MAN IBIAS Register is a 14-bit register, configured as described below. MAN IBIAS Register Programming in the Manual Mode To program the BIAS DAC Register, the user must have Password Level 2 access. Also the BIAS-EN bit should be set to 0. To change the value, the MAN_CNTL Register (Table 02h, Registers FAh) is used to clock the MAN IBIAS value to register into the Bias DAC. The procedure for writing the DAC is then: Write the MAN IBIAS value with a write command. Set the MAN_CLK bit to a 1 with a separate write command. Clear the MAN_CLK bit to a 0 with a separate write command. Programming a 13-Bit DAC with a 14-Bit Register The MAN IBIAS Register is 14 bits, however, the Bias DAC is only 13 bits in resolution. The bit 27 (bit 7 of register F9h and bit 0 of register F8h) in the MAN IBIAS Register is redundant. The rollover occurs in the following manner: Increasing DAC value from 0000h to 3FFFh The lower 8 bits of the DAC are incremented using register F9h. When the register value reaches FFh, register F8h is incremented by 1 bit, and register F9h is set to 80h and starts incrementing. The process repeats until all bits are 1. Decreasing DAC value from 3FFFh to 0000h Decrement the lower 8 bits of the DAC by using register F9h. When the register value reaches 00h, register F8h is decremented by 1 bit, and register F9h is set to 7Fh and starts decrementing. The process repeats until all bits in both registers are at 00h. Conclusion The programming procedure presented here controls the Bias DACs in the DS1863/DS1865 PON controllers. フィードバックをお寄せください。 内容に満足されましたか、あるいは満足されていませんか？もっと良いページにできると思いますか？あるいは、単なるコメントでも結構です。フィードバックをお待ちしています。—マキシムはお客様からいただく訂正、提案を元に改善していきます。 このページを評価し、フィードバックを送信する。 自動アップデート お客様が関心のある分野でアプリケーションノートが新規に掲載された際に自動通知Eメールの受信を希望する場合は、EE-Mail™にご登録ください。 その他の情報   APP 4196: Mar 17, 2008 DS1863 監視機能内蔵、バーストモードPONコントローラ フルデータシート (PDF, 788kB) 無料 サンプル DS1865 PONトライプレクサ制御および監視回路 フルデータシート (PDF, 532kB) 無料 サンプル   ダウンロード、PDFフォーマット (22kB)  AN4196, AN 4196, APP4196, Appnote4196, Appnote 4196