Philips TDA1541A S1 & S2 d/a converters 

The TDA1541A is a stereo 16-bit digital-to-analog converter (DAC). The ingenious design of the electronic circuit guarantees a high performance and superior sound quality. The TDA1541A is therefore extremely suitable for use in top-end hi-fi digital audio equipment such as high quality Compact Disc players or digital amplifiers.

Features
- High sound quality
- High performance: low noise and distortion, wide dynamic range
- 4 ´ or 8 ´ oversampling possible
- Selectable two-channel input format
- TTL compatible inputs.

Functional description
The TDA1541A accepts input sample formats in time multiplexed mode or simultaneous mode up to 16-bit word length. The most significant bit (MSB) must always be first. The flexible input data format allows easy interfacing with signal processing chips such as interpolation filters, error correction circuits, pulse code modulation adaptors and audio signal processors (ASP).
The high maximum input bit-rate and fast setting facilitates application in 8 ´ oversampling systems (44.1 kHz to 352.8 kHz or 48 kHz to 384 kHz) with the associated simple analog filtering function (low order, linear phase filter).

True 16-bit performance is achieved by each channel using three 2-bit active dividers, operating on the dynamic element matching principle, in combination with a 10-bit passive current divider, based on emitter scaling. All digital inputs are TTL compatible.

	TDA1541A/S2	TDA1541A/S1	TDA1541A	TDA1541A/R1
Typ. THD + N at full-scale at 0 dB	–97 dB	–95 dB	–95 dB	–95 dB
Typ. THD + N at –60 dB	-47 dB	-47 dB	-42 dB	-43 dB
Channel separation	98 dB	98 dB	98 dB	98 dB
Typ. signal-to-noise ratio	112 dB	112 dB	112 dB	112 dB
Full-scale output current	4.0 mA	4.0 mA	4.0 mA	4.0 mA
Package	DIL28	DIL28	DIL28	DIL28

The "select" version TDA1541A S1 progressed to become the TDA1541A S2, with an even stricter selective standard and a so-called double crown mark. In fact, previous "select" product levels were ealisy exceeded through improvements in the manufacturing process and manufacturing precision of the device. The TDA1541A S2 was installed in the Marantz CD-95Ltd together with the SAA7220P/B. Later, Marantz successfully employed the TDA1541A S2 16-bit D/A converter as a finishing touch in the Marantz Project D-1.

Production of the SAA7220P/B digital filter had stopped long before this, so Marantz technicians programmed an 8x over sampling digital filter circuit for use as a high speed DSP.

The legendary 16-bit CD player Marantz CD-7, which is still highly praised, was the last Marantz CD player to feature the TDA1541A S2. Since actual production of the TDA1541A S2 has stopped long before, the number of players that could be produced using this device was limited from the start. Marantz used their precious stock of TDA1541A S2 to design digital filter circuits with high-speed DSPs in the same way as the Marantz Project D-1. The Marantz CD-7 however used 4x over sampling equivalent to the SAA7220P/B and a primary noise shaping circuit modeled on the secondary noise shaping circuitry in the digital filter SAA7030 (used with the first 14-bit DAC TDA1540) but fitted with an on/off function.

Actually, since the phase characteristic could also be calculated, the digital filter was used to calculate the pass-through characteristics of the analog low-pass filter and its phase correction. In other words, the unit was engineered on the premise that the signal output from the CD player would be completely linear and receive no phase correction. In addition, a variety of other technologies have been used during the process of converting the digital signal back to analog. This concludes the history of the Philips multi-bit digital audio DACs.