MAX9850ETI+T Maxim Integrated Products, MAX9850ETI+T Datasheet - Page 20

• Manufacturer Part Number: MAX9850ETI+T
• Description: IC AMP AUDIO .095W STER 28TQFN
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive™r
• Type: Class ABr

Specifications of MAX9850ETI+T

• Output Type: Headphones, 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 95mW x 2 @ 16 Ohm
• Voltage - Supply: 1.8 V ~ 3.6 V
• Features: DAC, Depop, Digital Inputs, I²C, I²S, Line Level Inputs & Outputs, Mute, Shutdown, Volume Control
• Mounting Type: Surface Mount
• Package / Case: 28-WQFN Exposed Pad, 28-HWQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

where:
f
f
f
N
(register 0x8, bits B6–B0 and register 0x9, bits B7–B0).
Round the results of the equation to the nearest integer
value.
For example:
f
1) Solve for N
2) Round result to nearest integer value. 15053.
3) Convert to hex, 0x3CD.
4) Program MSB(14:8) with the MSB 0x3A and program
Table 7 provides examples of using master noninteger
mode with various MCLK frequencies to generate useful
LRCLK frequencies.
The DirectDrive line and headphone outputs of the
MAX9850 require a charge pump to create the internal
negative power supply. Set CPEN(1:0) = 11 in the
enable register (register 0x5, bits B5 and B4) to turn on
the charge pump. The negative charge-pump voltage
is established and the audio outputs are ready for use
approximately 1.4ms after CPEN is set to 11.
Stereo Audio DAC with DirectDrive
Headphone Amplifier
Table 7. Master Noninteger N
Note: The N values represent the combined MSB(14:8) and LSB(7:0) values.
20
ICLK
LRCLK
LRCLK
LRCLK
18.4320
16.9344
16.3840
12.5000
12.2880
12.0000
11.2896
MSB,LSB
9.2160
8.4672
8.4480
MCLK
(MHz)
LSB(7:0) with the LSB 0xCD).
______________________________________________________________________________________
= ICLK frequency. f
for proper DAC operation.
= LRCLK frequency.
= 44.1kHz, f
= decimal value of MSB(14:8) and LSB(7:0)
SF
2
2
2
1
1
1
1
1
1
1
MSB,LSB
ICLK
12.5000
12.2880
12.0000
11.2896
9.2160
8.4672
8.1920
9.2160
8.4672
8.4480
(MHz)
ICLK
, 15052.8.
= 12.288MHz.
ICLK
must be at least 176 x
5CE1
3EEA
5CE1
5D17
4000
45A9
5555
4189
5555
48
Charge Pump
MSB,LSB
3ACD
39CE
4E66
3C36
4E66
5555
5833
4000
5555
5587
44.1
Examples
3DEB
2AAB
3DEB
2BB1
38E4
4000
2E71
38E4
3E10
29F1
32
LRCLK OUTPUT FREQUENCY (kHz)
The state of CP(4:0), in the charge-pump register (register
0x7, bits B4–B0), determines whether the charge-pump
oscillator is derived from the internal 667kHz oscillator or
from MCLK. Set CPEN(1:0) = 11 and set CP(4:0) = 0x00
to enable the internal oscillator. The charge pump runs
independent from MCLK when the internal oscillator is
enabled allowing the charge pump to operate when the
DAC is disabled or when only the line inputs are used. No
MCLK is required when only the line inputs are used.
The switching frequency of the charge pump is well
beyond the audio range and does not interfere with audio
signals. The switch drivers utilize techniques that mini-
mize noise generated by turn-on and turn-off transients.
Although not typically required, additional high-frequency
noise attenuation can be achieved by increasing the size
of C2 and the PV
Diagram/Typical Operating Circuit).
Derive the charge-pump clock from MCLK by program-
ming CP(4:0) to a non-zero value based on the following
equation:
where:
f
f
667kHz ±20% for proper operation.
SF = MCLK scale factor. SF is the decimal value of
IC(1:0) + 1.
N
0x7, bits B4–B0). N
deriving the charge-pump clock from I
2AAB
2AAB
20C5
22D4
2E8C
2E71
2000
2E71
MCLK
CP
3000
1F75
CP(4:0)
24
N (15-BIT hex VALUE)
= charge-pump clock frequency. Ensure f
= MCLK frequency.
= rounded decimal value of CP(4:0) (register
22.05
2AAB
2C1A
1CE7
2AAB
2AC3
1D66
1E1B
2733
2000
2733
N
CP
DD
( : )
4 0
CP(4:0)
bypass capacitor (see the Functional
1C72
1EF6
15D8
1C72
1EF6
2000
14F9
1555
1738
1F08
16
=
2
must be greater than 1 when
×
f
0FBB
116A
1555
1738
1800
1000
1062
1555
1738
1746
MCLK
f
CP
12
×
SF
CLK
11.03
160D
0EB3
139A
0E73
0F0E
1000
139A
1555
1555
1562
.
0AAB
0AEC
0A7C
0B9C
0E39
0F7B
0E39
0F7B
1000
0F84
CP
8
=