LC78835K Datasheet, PDF (11/14 Pages) Sanyo Semicon Device – 18 Bits Digital Filter and D/A Converter for Digital Audio

LC78835K, 78835KM
• Pulse-Width Modulation (PWM) D/A Converter
This is a 3-bit circuit that applies pulse width modulation to voltages V2 and V1 output from the R-string D/A
converter to produce an 8-way division. Depending on the value of the data in bits D8 to D6, one of the voltages,
V2 or V1, is output to the CH1OUT (or CH2OUT) pin.
• Level Shift D/A Converter
The variable resistors VRH and VRL are connected in series to the two ends of the R-string D/A converter
resistance, configuring a 6-bit D/A conversion circuit. Depending on the values of the data in the LSBs (bits D5 to
D0), VRH and VRL change as follows.
(1) The sum of VRH and VRL is constant, irrespective of the data value.
(2) Irrespective of the data value, VRH and VRL are in the range of 0 to 63R/512 (where R is the unit resistance of
the R-string D/A converter) and resistance changes in R/512 steps in accordance with the data value.
This means that the R-string D/A converter outputs, V2 and V1, each vary in the range of 0 to 63 × ∆V/512 (∆V =
(VH - VL)/512) in ∆V/512 steps.
— Vref H/L, REF H/L Pins
The voltage on the Vref pins, used to apply the reference voltage to the resistance strings, are usually set so that
VrefH = AV_DD and VrefL = AGND. In addition, a 10 µF rated condenser connects REFH and AGND as well
as REFL and AGND. When VrefH = 5.0 V, VrefL = 0 V, the LC78835K on-chip RH and RL resistors
maximum output amplitude at 0 dB playback is output in the 3.0 Vp-p range extending from a minimum 0.6 V
to maximum 3.6 V.
No. 4624-11/14