AD1954YST Analog Devices Inc, AD1954YST Datasheet - Page 32

• Manufacturer Part Number: AD1954YST
• Description: IC DAC AUDIO 3CH 26BIT 48-LQFP
• Manufacturer: Analog Devices Inc
• Series: SigmaDSP®r

Specifications of AD1954YST

• Rohs Status: RoHS non-compliant
• Number Of Bits: 26
• Data Interface: Serial
• Number Of Converters: 3
• Voltage Supply Source: Analog and Digital
• Power Dissipation (max): 510mW
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Settling Time: -

APPENDIX
Cookbook Formulae for Audio EQ Biquad Coefficients
(Adapted from Robert Bristow-Johnson’s Internet Posting)
For designing a parametric EQ, follow the steps below.
1. Given:
2. Compute intermediate variables:
AD1954
A = 10
Frequency
Q
dB_Gain
Sample_Rate
 = 2    Frequency/Sample_Rate
sn = sin()
cs = cos()
 = sn/(2  Q)
(dB_Gain/40)
–32–
3. Compute coefficients:
4. The transfer function implemented by the AD1954 is given by:
Y(n) = a1  y(n – 1) + a2  y(n – 2) + b0  x(n)
b0 = ( 1 + A  )/( 1 + (/A))
b1 = –2  cs/( 1 + (/A))
b2 = (1 – (  A))/(1 + (/A))
a1 = 2  cs/(1 + (/A)) = –b1
a2 = –( 1 – (/A))/( 1 + (/A))
H(Z) = (b0 + b1  Z – 1 + b2  Z – 2)/
Note the inversion in sign of a1 and a2 relative to the more
standard form. This form is used in this document because
the AD1954 implements the difference equation using the
formula below.
+ b1  x(n – 1) + b2  x(n – 2)
(1 – a1  Z – 1 – a2  Z – 2)
REV. A