SimCom SIM8905A User Manual page 20

Full-scale input voltage
Input impedance
Capless input
Input disabled
Input capacitance
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 100KΩ 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.
HS_DET
HPH_R
HPH_L
MIC2P
GND_MIC
HPH_GND
Module
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
16 Ω load f = 1.02 kHz, 0 dB FS; VDD_CP* = 1.95 V
Output power
32 Ω load f = 1.02 kHz, 0 dB FS; VDD_CP* = 1.95 V
16 Ω load f = 1.02 kHz, 0 dB FS; VDD_CP* = 1.95 V
Full-scale
output Voltage
32 Ω load f = 1.02 kHz, 0 dB FS; VDD_CP* = 1.95 V
Output load
Single-ended 1 kHz input. Input signal
level required to get 0 dBFS digital output
Capless input
Close to headset jack
0R
0R
33pF
33pF 33pF
Figure 21: H eadset reference circuit
Test conditions
Smart Machine Smart Decision
-0.5
1.0
3.0
-
1000 OHM@100MHZ
1000 OHM@100MHZ
1000 OHM@100MHZ
1000 OHM@100MHZ
1000 OHM@100MHZ
1000 OHM@100MHZ
100K
Min
15.6
27.0
0.50
0.96
13.0
20
0 0.5 dBV
MΩ
- -
MΩ
- -
- 15 pF
Headset Jack
TVS
Typ Max Units
21.5 25.5 mW
30.8 32.0 mW
0.59 0.64 Vrms
0.99 1.00 Vrms
Ω
16/32 -