Rev 1.0
1/27/14
28
28
Reference Guide
Interfaces
Figure 19. Equivalent Circuit of CSPK
Table 14. Electrical Characteristics of CSPK for USR3500
Parameters
Min
Typ
Max
Unit
Biasing voltage
CSPKxP and CSPKxN
-1.5
1.5
mV
Output swing
voltage
RL=16
Ω
: AT+VGR=-1600*; single-ended
-
1.7
Vpp
RL=32
Ω
: AT+VGR=-1600*; single-ended
-
1.9
2.75
Vpp
RL
Load resistance
14.5
32
-
Ω
IOUT
Output current; peak value; RL=16
Ω
-
40
85
mA
Output current; peak value; RL=32
Ω
-
22
-
mA
POUT
RL=16
Ω
; AT+VGR=-1600*
-
25
-
mW
RL=32
Ω
; AT+VGR=-1600*
-
16
27
mW
RPD
Output pull-down resistance at power-down
28
40
52
k
Ω
*
The output voltage depends of the output speaker gain set by AT command. Refer to the AT Commands
Interface Guide at
http://www.usr.com/support/3500
. This value is given in dB, but it’s possible to toggle this to index value.
Refer to the following table for the list of recommended speaker characteristics.
Table 15. Recommended Speaker Characteristics
Feature
Values
Type
10mW, electro-magnetic
Impedance
Z = 30 to 50
Ω
Sensitivity
110dB SPL min. (0dB = 20
µ
Pa)
Frequency response
Compatible with GSM specifications