IC-DC_17 Datasheet, PDF (13/19 Pages) IC-Haus GmbH – 2-CHANNEL BUCK/BOOST DC/DC CONVERTER

iC-DC
2-CHANNEL BUCK/BOOST DC/DC CONVERTER
LINEAR REGULATORS VCC1 AND VCC2
Rev B1, Page 13/19
To achieve as low an interference voltage as possible,
even with small filter capacitors C_VH1 and C_VH2, an in-
dependent linear regulator is connected after each of
the intermediate voltages VH1 and VH2.
Output voltages VCC1 and VCC2 can each be adjusted
using a voltage divider at CFG1 and CFG2 within a
range of 1.5 to 5.5 V ±5 % and according to Equations
1 and 2.
V _VCC1
= V(RREF) × (1 +
R_{1 )}
R₂
(1)
and
V _VCC2
= V(RREF) × (1 +
R_{3 )}
R₄
(2)
NB: R₁ + R₂ and R₃ + R₄ = 10 kΩ up to 50 kΩ
V(RREF) Electrical Characteristics 401
Inputs CFG1 and CFG2 can also be directly connected
to the relevant output voltage VCCx or GNDA. The
resulting voltages are given in Tables 4 and 5.
VCC1 output voltage
Potential at CFG1
GNDA
VCC1
Voltage divider
VCC1
3.3 V
5.0 V
1.5 V to 5.5 V
Table 4: VCC1 settings
lators are deactivated, iC-DC is in standby mode (see
DESCRIPTION OF FUNCTIONS/Standby).
Switched output voltages
The two pins POE1 and POE2 are triggered by monitor
outputs V1OK and V2OK and provide voltages drawn
from VCC1 or VCC2. This enables the supply of spe-
cific circuitry in a component group (e.g. EEPROMs) to
be switched on only after VCC1 or VCC2 have reached
their steady state.
Voltage monitor self-test
Using pin TEST the voltage monitoring comparators at
V1OK and V2OK can be tested during ongoing opera-
tion. The undervoltage and overvoltage thresholds of
V1OK and V2OK are checked in turn with each test.
For this purpose, pin TEST is increased to above the
threshold voltage by an external driver. Correct func-
tioning is signaled by low signals at pins V1OK and
V2OK. The function of the connected POE1 and POE2
outputs remains unaffected.
Current carrying capacity
iC-DC’s current carrying capacity depends on set out-
put voltage VCCx and input voltage VB. Figure 4 shows
the current carrying capacity dependent on the input
voltage for various output voltages, measured on the
iC-DC EVAL DC1D evaluation board. The internal re-
verse polarity protective circuit was bridged (VB = VBR)
to increase the current carrying capacity.
VCC2 output voltage
Potential at CFG2
GNDA
VCC2
Voltage divider
VCC2
2.5 V
3.3 V
1.5 V to 5.5 V
Table 5: VCC2 settings
The regulators have been compensated internally so
that they are stable in no-load operation without an ex-
ternal capacitor. Stability across the entire load range
is guaranteed by the minimum capacitances for C_VCC1
and C_VCC2 given in the electrical characteristics. The
outputs are current limited to protect them against de-
struction in the event of a short circuit.
The two linear regulators can be switched on and off
independently by inputs ENV1 and ENV2. If both regu-
500
450
400
350
300
250
200
150
100
50
0
0.0
VH (>7.2V)
5V VCCx
3,3V VCCx
2,5V VCCx
1,5V VCCx
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
Input Voltage VB [V]
Figure 4: Current carrying capacity for various out-
put voltages dependent on VB (VB = VBR)