Smart Machine Smart Decision
20
Full-scale input voltage
Single-ended 1 kHz input. Input signal
level required to get 0 dBFS digital output
-0.5
0
0.5
dBV
Input impedance
Capless input
Input disabled
1.0
3.0
-
-
-
-
MΩ
MΩ
Input capacitance
Capless input
-
-
15
pF
Headset
Stereo class-
AB headphone supports 16 Ω, 32 Ω, and up to 50 KΩ loads. Its typical output power at 1.02 KHz and
THD + N
≤
1% is:
21.5 mW
with
16 Ω loads, 0 dBFS and -4.5 dB gain
30.8 mW with 32 Ω loads, 0 dBFS and 0 dB gain
A 100K
Ω pull-down resistor is integrated at HPH_L pin, which could be used for mechanical insertion or removal
detection through HS_DET pin. Figure 22 shows the reference circuit for normally-closed (NC) type headset jack.
HPH_R
Module
HPH_L
0R
0R
HS_DET
MIC2P
GND_MIC
HPH_GND
100K
33pF
33pF
33pF
Headset Jack
TVS
Close to headset jack
1000 OHM@100MHZ
1000 OHM@100MHZ
1000 OHM@100MHZ
1000 OHM@100MHZ
1000 OHM@100MHZ
1000 OHM@100MHZ
Figure 21:
H
eadset reference circuit
Note:
1.
SIM8905A also supports NO/NC type headset jack with detect pin on HPH_L or GND.
2.
HPH has a negative swing and requires a bi-directional TVS diode.
Table 10: Headphone output performance specifications
Parameter
Test conditions
Min
Typ
Max
Units
Output power
16
Ω load f = 1.02 kHz, 0 dB FS; VDD_CP* = 1.95 V
15.6
21.5
25.5
mW
32
Ω load f = 1.02 kHz, 0 dB FS; VDD_CP* = 1.95 V
27.0
30.8
32.0
mW
Full-scale
output Voltage
16
Ω load f = 1.02 kHz, 0 dB FS; VDD_CP* = 1.95 V
0.50
0.59
0.64
Vrms
32
Ω load f = 1.02 kHz, 0 dB FS; VDD_CP* = 1.95 V
0.96
0.99
1.00
Vrms
Output load
13.0
16/32
-
Ω
