AK5371AVQP AKM Semiconductor Inc, AK5371AVQP Datasheet - Page 12

• Manufacturer Part Number: AK5371AVQP
• Description: IC ADC STER W/USB 16BIT 48LQFP
• Manufacturer: AKM Semiconductor Inc
• Type: ADCr

Specifications of AK5371AVQP

• Resolution (bits): 16 b
• Sampling Rate (per Second): 8k ~ 48k
• Data Interface: USB
• Voltage Supply Source: Analog and Digital
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 48-LFQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 974-1030

■
The AK5371A supports two audio formats: 16bit/mono and 16bit/stereo. This feature can avoid the unnecessary occupation of USB
bandwidth. 16bit/mono is assigned to <Interlace 1, Alt1>, 16bit/stereo is assigned to <Interface 1, Alt2>. The A/D data on USB bus is
LSB first, Left channel first. When 16bit/mono audio format is selected, the AK5371A outputs left channel data on the USB bus. Audio
format is changed by “Set Interface” Request.
■
The AK5371A operates as Asynchronous Device. A/D converter in the AK5371A operates asynchronously with USB SOF timing.
The data from A/D converter are sent continuously to a buffer memory while the data are burstly transferred at the interval of SOF on
the USB. In order to arbitrate the difference of timing, AK5371A has a FIFO memory with a capacity of 2-frame depth .The average
sampling rate calculating from USB frame should be in accordance with A/D sampling rate (fs).
The AK5371A sends all A/D samples that were stored in the last frame to avoid overflow or underflow of FIFO. The following figure
shows an example. When sampling frequency is set to 44.1kHz, the AK5371A sends 45 samples once per ten times, and sends 44
samples in other frames. Average frequency is 44.1kHz. See Figure 7.
■
When idle state continues for 3ms, the AK5371A goes to suspend state and forces almost all blocks including PLL, ADC block and mic
bias into stopping in order to observe 500μA, which is USB suspend current requirement.
The device resumes the normal operation within 30ms after the device receives resume signal.
In the normal operation, MICBIAS outputs the voltage to supply the microphone’s bias voltage.
SUSN pin shows USB bus status; suspend mode (“L") or normal operation (“H").
SUSN pin can be used for external power control.
The AK5371A is very low power device at both normal state and suspend state. However, note that USB suspend current requirement,
500μA, specifies the current which is totally consumed by not only the AK5371A, by also regulator(s), and resistors. Therefore, low
power regulator should be selected to design USB microphone.
■
When the AK5371A receives “SET_FEATURE_UNIT_CONTROL” request, the device decodes the request and sets the value. Note
that only CUR value is valid for “SET_FEATURE_UNIT_CONTROL” request, and that MIN/MAX/RES value is invalid.
When the AK5371A receives “GET_FEATURE_UNIT_CONTROL” request, the device decodes the request and returns the value to
the host. CUR/MAX/MIN/RES value is valid for "Get Volume Request", but only CUR value is meaningful for "Get Mute Request".
When the AK5371A receives “SET_ENDPOINT_CONTROL” request, it changes sampling frequency(fs). If fs is not supported, the
device forces to set the appropriate fs which it supports. When the AK5371A receives “GET_ENDPOINT_CONTROL” request, it
sends back the current value to the host.
MS0546-E-01
Audio Format of the AK5371A
Synchronization
Power Management Control
Feature Unit Control & Frequency Control
N Frame
44 samples
(N+1) Frame
44 samples
Figure 7. Synchronization
- 12 -
(N+9) Frame
45 samples
(N+10) Frame
44 samples
2008/11