Application Information
1. Power Save Function
• Power save function is also performed at PS (pin20). The truth table is as follows:
VDD
SW (pin3)
PS (pin20)
Input
Function
Input
Function
L CAPA(pin25) OFF L Power Save ON
20
H CAPA(pin25) ON H Power Save OFF
FAN8040
PS CNTL
Bias Circuit
Figure 1. Truth table of Gain selection and Mute Function
• When the PS (pin 20) is hige level (above 2V), the bias circuit is enable. On the other hand, when the PS(pin20) is low level
(under 0.5V), the bias circuit is disabled.
• When the CAPA(pin3) is low level, the CAPA (pin25) is opened in Figure. 4.
2. TSD (Thermal Shutdown) Function
• When the chip temperature rises above 175°C, then the 4-channels BTL driver output circuit will be muted.
The TSD circuit has the hysteresis temperature of 25°C.
4. Balanced Transformerless(BTL) Driver (CH1, CH2 and CH3)
• CH1, CH2 and CH3 drive parts are composed of internal filter, V-I converter and output power amplifiers.
FWD
REV
PVCC
I1
F
S1
R1=100KΩ
INTERFACE
R
S2
C1=25㎊
A
I2
Buffer1
Buffer2
VREF
Figure 2. Schematic of BTL Driver (CH1, CH2 and CH3)
F
R
S1
S2
L
L
OFF OFF
L
H
OFF ON
H
L
ON OFF
H
H
ON ON
H : above 2.4 [V]
L : under 0.5 [V]
Table 1. Truth table of internal switches operation
OUT1
OUT2
9