IC-DC IC-Haus, IC-DC Datasheet - Page 11

• Manufacturer Part Number: IC-DC
• Description: 2-CHANNEL BUCK/BOOST DC/DC CONVERTER
• Manufacturer: IC-Haus

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DC/DC converter iC-DC generates two regulated volt-
ages of VH1 and VH2 from voltage VBR. These presta-
bilize the two linear regulators VCC1 and VCC2. A
third voltage of VH, also regulated, is generated to
drive these linear regulators. Voltage supply VB may
be either above or below the output voltages. Figure 1
shoes the basic function principle of iC-DC. Switches
S1 to S6 and diode D1 have been implemented on the
chip. The inductor, capacitors, and load resistors are
external devices.
DESCRIPTION OF FUNCTIONS
iC-DC
2-CHANNEL BUCK/BOOST DC/DC CONVERTER
VB
Figure 1: Principle of operation of the converter
D1
D1
VBR
Dual 3.3V/5V BOOST/BUCK SMPS, 05.05.2008 11:51:33
400mA
300mA
200mA
100mA
0
I(LVBH)
4V
3V
2V
1V
0
-1V
V(VBL)
8V
6V
4V
2V
0
V(VHL)
S1
S1
S3
S3
VBL
LVBH
LVBH
S2
S2
8.887ms
Figure 2: Converter current/voltage characteristics (VB = 4 V)
VHL
S4
S4
S5
S5
S6
S6
VH1
VH2
VH
CVH
CVH
CVH1
CVH1
CVH2
CVH2
8.888ms
RVH
RVH
RVH1
RVH1
RVH2
RVH2
Time (linear) [Plot 0]
Another feature of iC-DC is that bias voltages VH1 and
VH2 adjust themselves automatically to approximately
400 mV using the selected VCC1 or VCC2 voltage.
This results in minimum power dissipation as only a
low amount of voltage is lost through each of the linear
regulators.
Charge/discharge phase
During the charge phase switches S
with the internal clock. A linearly increasing current
flows through coil LVBH. The energy from supply VBR
is stored in the coil’s magnetic field.
Switches S
and one of the switches S
rent can continue to flow in the coil and is supplied to
the relevant capacitor and relevant load. Figure 2 de-
scribes the resulting course of the current and voltage.
The current rise and fall times depend on the inductor
voltage.
1
and S
8.889ms
2
open for discharging. Switch S
4
/S
5
/S
6
are closed. The cur-
Rev A3, Page 11/19
8.89ms
1
and S
2
close
3
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