3. UNDER / HIGH VOLTAGE PROTECTION CIRCUIT
VREF BG
R1
+
R2
−
Mute control
Q
[UNDER VOLTGE PROTECTION]
• [UNDER VOLTGE PROTECTION]
• Normal state: VBGR = 2.5V < V1 = VCC × R2 / (R1 + R2)
• Normal state: VZ = V1 + V2 + V3 + VR
• [HIGH VOLTAGE]
• Mute state: V1 < VBGR (VCC is below 4V)
• Mute state: VCC > VZ (VCC is above 20V)
KA3030D
VCC
V1
V2
V3
VR
Mute control
Q
[HIGH VOLTAGE]
9