connections.txt

TUSB3200   CS4272          AK4384   Comment
19 P3.4                             USB LED ("T0")
20 P3.5                             MIDI LED ("T1")
24 P1.0    12 SDA/CDIN              ("INT3")
25 P1.1    11 SCL/CCLK              ("INT4")
26 P1.2                             unused? (high level)
28 P1.3    13 AD0/CS                ("INT6")
29 P1.4                             unused? (high level)
30 P1.5                             TP1/LD1 ("T2EX")
31 P1.6                             Amplifier power control (1=off, 0=on) ("CLKOUT") (high on power-on, then low)
32 P1.7                             Codec reset (1=reset, 0=normal) via TR1 ("T2") (high on power-on, then low)
34 CSCLK                            Connected to MCLKI2?
35 CSYNC
36 CDATO   7 SDIN
38 CDATI                   3 SDTI
40 CSCHNE  6 SDOUT (via R)
44 MCLKO   3 MCLK
45 MCLKO2                           Synchronizing freq for 48V phantom power step-up (384KHz @ 48KHz sampling rate)
47 MCLKI                            Tied to DGND/DVss
48 MCLKI2  5 SCLK          2 BICK
  TR1 out  14 RST          5 PDN
                           9 P/S    Tied to VDD (parallel mode, no SPI control)

I2S Mode 4:
CSYNC:  LRCK
CSCLK:  SCLK
CDATO:  SDOUT1  CS4272
CDATI:  SDOUT2  AK4384
CRESET: SDOUT3
CSCHNE: SDIN1   CS4272

MCLKO?  MCLK   12.3MHz
MCLKI2? SCLK    3.08MHz
CDATO?  SDOUT1 714.3kHz?
CSYNC          23.5kHz

LM3488:
FA/SYNC/SD: 26KOhm? (~500kHz)

Feedback reference voltage: 1.26V
Feedback divider: 22kOhm + 621 Ohm => 45.9V setpoint?
 (1.26 / (621 / (22000 + 621)) => 45.90163)

Isense threshold voltage (Vsense): 156mV
Isense shortcircuit detection voltage (Vsc): 343mV
Isense feedback resistor: 0.33Ohm
=> Threshold current ~472mA

R46: 1.5kOhm ("The EIA-96 SMD resistor code 18B stands for 1.5 kΩ / 1%" matches the measured value)
R99: 11kOhm ("EIA-96 SMD resistor code 05C stands for 11 kΩ / 1%" matches the measured value)

R99 is part of the compensation network

R46 is the sync series resistor (but seems to be too small?!?)
DS recommends
Toff(sync)(us)  Rsync range kOhm
1 (~1MHz)       5-13
2               20-40
3               40-65
4               55-90
5               70-110
6               85-140
7               100-160
8               120-190
9               135-215
10 (~100kHz)    150-240

DS Tfa curve shows ~35 kOhm for 384kHz if Tfa-based timing is used?

The step-up SYNC setup is not fail-safe:
- If fSYNC is too high it fails to switch correctly and draws
  overcurrent and the LM3488 overcurrent protection is not tripping.
- If the MCLKO2 is not switching, SYNC is kept low (should be high for
  step-up power-down), again causing the MOSFET gate to be kept high
  and drawing overcurrent.
- At least the power control signal (P1.6) will gate the the SYNC
  signal at high level, which is safe (LM3488 power-off)


Danger Will Robinson:
  With wrong GPIO settings (Or bad codec settings?) it's possible to
  draw overcurrent when enabling 48V phantom power...
  (Found it! 3MHZ on the FA/SYNC/SD pin is too much [connected to MCLKO2 via quad-nor])