THV3543_Rev.1.00_E
ꢀ
Switching Channel Output Voltage Mode
Output voltage mode of switching channel can be chosen the adjustable mode or the fixed mode, according to
the setting of VO1_IN pin.
When CHꢀ1 output is connected directly to VO1_IN pin, the output voltage is turned into the fixed mode. CHꢀ1
is fixed at 15.6V, VGH at 35.6V and VGL at ꢀ6V. When VO1_IN pin is connected to ground, the output voltage
is turned into the adjustable mode. Output voltage of CHꢀ1, VGH and VGL can be set by an external resistance.
CHꢀ2 is fixed at 3.3V in both modes.
ꢀ
Output Voltage Setting (Adjustable Mode)
In CHꢀ1, the voltage on INV1 pin will be equal to the voltage on VREF by the action of feedback (See Figure 6). The
voltage on INV1 pin is divided Vout1 by R1 and R2.
Therefore,
R2
Vout1
R1
Vout1×
= VREF
FB1
C2
R1+ R2
C1
Thus,
Error AMP1
R3
R1
R2
R1
R2
ꢀ
PWM
Comp.
Vout1 = VREF× 1+
= 1.2× 1+
INV1
+
VREF
=1.2V
R2
Figure 6. CHꢀ1 Output Voltage Setting
In VGH, the voltage on VGH_FB pin is controlled to be equal to the voltage on VREF (See Figure 7). The voltage on
INV_VGH pin is divided voltage on VGH by R4 and R5.
Therefore,
VGH
R4
R5
R4
R5
VGH = VREF× 1+
= 1.2× 1+
R4
COMP
ꢀ
VGH_FB
Output
Circuit
+
VREF
=1.2V
R5
Figure 7. VGH Output Voltage Setting
THine Electronics, Inc.
Copyright© 2011 THine Electronics, Inc.
15/19
THINE [ THINE ELECTRONICS, INC. ]
