ICHAUS IC-WDSO8-TP

iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 1/12
FEATURES
APPLICATIONS
♦
♦
♦
♦
♦ 5 V resp. 3.3 V supply e.g. from
24 V industrial network
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
Input voltage 8 to 36 Vdc
Highly efficient down converter
Switching transistor and free-wheeling diode integrated
Adjustment of the regulator cut-off current with external
resistor
Integrated 100 kHz oscillator without external components
Switching frequency above the audible range
Two downstream linear regulators with 200 mA/25 mA output
current
Three different output voltage combinations of 3.3 V version
available (see Block Diagram)
Small residual ripple with low capacitances in the µF range
Fault message at overtemperature and undervoltage at
current-limited open-collector output
Shutdown of switching regulator at overtemperature
Internal reference voltages
ESD protection
Low space requirement with SO8 resp. tiny DFN10 package
PACKAGES
DFN10
SO8
(optional with
thermal pad)
♦ Option: enhanced temperature range of -40 to 85 °C
BLOCK DIAGRAM
VB (8...36 V)
RVB
LVH
1Ω
220µH
8
4.7µF
2
VB
VBR
3
CVH
4.7µF
5
VH
VHL
VH SWITCHING CONVERTER
WD
WDA
WDB
WDC
VCC
+5 V
+3.3 V
+3.3 V
+5 V
VCCA
+5 V
+3.3 V
+5 V
+3.3 V
OSCILLATOR
VCC
ERROR
1
6
(200 mA)
CVCC
4.7µF
NER
TEMPERATURE
VCC REGULATOR
UNDERVOLTAGE
ERROR DETECTION
iC−WD
REFERENCE
VCCA
7
(25 mA)
CVCCA
1µF
VREF
VCCA REGULATOR
GND
4
Pin numbers for SO8 package
Copyright © 2007 iC-Haus
http://www.ichaus.com
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 2/12
DESCRIPTION
The device iC-WD is a monolithic switching regulator with two downstream 5 V resp. 3.3 V linear regulators. In view of the high efficiency of the down
converter for an input voltage range of 8 to 36 V, the
iC-WD family is well-suited for industrial applications
which require a stabilised 5 V resp. 3.3 V power supply with minimal power dissipation and few components.
Switching transistor, free-wheeling diode and oscillator are integrated, limiting the necessary external
elements for the switching regulator to the inductor,
the back-up capacitor and one resistor. This resistor
determines the regulator’s cut-off current and thus its
efficiency in the particular application at hand.
The downstream linear regulators feature a low residual ripple even with relatively small smoothing capacitors in the µF range. The output voltages have an
internal reference and are specified ±5% in the entire operating and temperature range. The use of two
mutually independent linear regulators makes it possible to isolate the voltage supply of sensitive analogue circuits or sensors from the supply for digital
and driver devices.
The chip temperature and the output voltages are
monitored. A fault is signalled via the current-limited
open-collector output NER, for example by an LED
display or a logical link with other error signals from
the system. In the event of overtemperature, the
switching regulator is disabled to reduce the power
dissipation of the chip.
PACKAGES SO8, SO8tp, DFN10 to JEDEC Standard
PIN CONFIGURATION SO8, SO8tp
(top view)
iC−WD Code...
...
...yyww
1
NER
2
VBR
3
VHL
4
GND
PIN FUNCTIONS
No. Name Function
8
VB
7
VCCA
6
VCC
5
VH
1
2
3
4
5
6
7
8
NER
VBR
VHL
GND
VH
VCC
VCCA
VB
Error Output
Pin for shunt
Pin for inductor
Ground (reference voltage)
Intermediate Voltage
Output (200 mA)
Output (25 mA)
Supply Voltage
The Thermal Pad (optional) is to be connected to a Ground Plane on the PCB.
PIN CONFIGURATION DFN10
(top view)
PIN FUNCTIONS
No. Name Function
1
10
2
9
3
4
iC−WDx
...
8
7
...yyww
5
6
1
2
3
4
5
6
7
8
9
10
NER
n.c.
VBR
VHL
GND
GND
VH
VCC
VCCA
VB
Error Output
Pin for shunt
Pin for inductor
Ground (reference voltage)
Ground (reference voltage)
Intermediate Voltage
Output (200 mA)
Output (25 mA)
Supply Voltage
The Thermal Pad is to be connected to a Ground Plane on the PCB.
Orientation of the package label ( WDx ...yyww) may vary.
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 3/12
ABSOLUTE MAXIMUM RATINGS
Values beyond which damage may occur; device operation is not guaranteed.
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Max.
G001 VB
Supply Voltage
-0.3
38
G002 V(VBR)
Voltage at VBR
-0.3
38
V
G003 I(VHL)
Current in VHL
-800
800
mA
G004 V(VH)
Voltage at VH
-0.3
8
V
G005 I(VCC)
Current in VCC
-500
4
mA
G006 I(VCCA)
Current in VCCA
-100
4
mA
G007 V(NER)
G008 Vd()
Voltage at NER
-0.3
38
V
2
1.5
kV
kV
G009 Tj
Junction Temperature
-40
150
°C
G010 Ts
Storage Temperature
-40
150
°C
ESD Susceptibility at all pins
Peak duration ≤ 50 µs
HBM, 100 pF discharged through 1.5 kΩ
WDB, WDC
V
THERMAL DATA
Operating Conditions: VB = 8...36 V, LVH = 220 µH, Ri(LVH ) < 2 Ω, CVH = 4.7 µF, RVB = 1 Ω
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
T01
Ta
Operating Ambient Temperature Range
(extended temperature range on request)
T02
Rthja
Thermal Resistance Chip to Ambient
T03
Rthja
T04
Rthja
Typ.
-25
Max.
70
°C
SMD mounting on PCB, without additional
cooling
170
K/W
Thermal Resistance Chip to Ambient
SMD mounting on PCB, with approx. 3 cm²
cooling surface (see Evaluation Board)
100
K/W
Thermal Resistance Chip to Ambient
SMD mounting on PCB, therm. pad soldered
to approx. 2 cm² cooling area
60
K/W
All voltages are referenced to ground unless otherwise stated.
All currents into the device pins are positive; all currents out of the device pins are negative.
30
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 4/12
ELECTRICAL CHARACTERISTICS
Operating Conditions: VB = 8...36 V, LVH = 220 µH, Ri(LVH) < 2 Ω, CVH = 4.7 µF, RVB = 1 Ω, Tj = -40...125 °C, unless otherwise noted
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Typ.
Max.
Total Device
001
VB
Permissible Supply Voltage
Range
Linear Regulator VCC (200 mA)
101 VCCnom
Output Voltage
102
I(VCC)
Permissible Load Current
103
CVCC
Min. Output Capacity for Stability
104
VCCrip
Residual Ripple
Linear Regulator VCCA (25 mA)
201 VCCAnom Output Voltage
202
I(VCCA)
Permissible Load Current
203
CVCCA
Min. Output Capacity for Stability
204
VCCArip
Residual Ripple
Switching Regulator VB, VBR, VHL, VH
301 I0(VB)
Quiescent Current in VB
302
303
304
305
I(VB)
I(VB)
I(VB)
I(VB)
Current in VB with partial load
Current in VB with partial load
Current in VB with full load
Current in VB with full load
8
I(VCC) = -200...0 mA;
WD, WDC
WDA, WDB
4.75
3.135
-200
Evaluation Board (see Fig. 8), Tj = 27 °C:
I(VCC) = -200 mA, I(VCCA) = -20 mA
I(VCCA) = -25...0 mA;
WD, WDB
WDA, WDC
4.75
3.135
Evaluation Board (see Fig. 8), Tj = 27 °C:
I(VCC) = -200 mA, I(VCCA) = -20 mA
0
mA
µF
mA
mA
mA
I(VCC) + I(VCCA) = -100 mA, Tj = 25 °C,
WD, WDB, WDC;
VB = 12 V
VB = 24 V
VB = 30 V
72
37
30
mA
mA
mA
I(VCC) + I(VCCA) = -100 mA, Tj = 25 °C, WDA;
VB = 12 V
VB = 24 V
VB = 30 V
61
33
24
mA
mA
mA
I(VCC) + I(VCCA) = -200 mA, Tj = 25 °C,
WD, WDB, WDC;
VB = 12 V
VB = 24 V
VB = 30 V
132
69
55
mA
mA
mA
I(VCC) + I(VCCA) = -200 mA, Tj = 25 °C, WDA;
VB = 12 V
VB = 24 V
VB = 30 V
116
62
43
mA
mA
mA
Switching Frequency with no load I(VCC) = 0, I(VCCA) = 0
20
fl(VHL)
Switching Frequency with load
60
Voltage VH with load
V
V
4.5
3.0
2.5
f0(VHL)
Vl(VH)
5.25
3.465
I(VCC) = 0, I(VCCA) = 0, Tj = 25 °C;
VB = 12 V
VB = 24 V
VB = 30 V
308
309
312
5.00
3.30
mVss
mVss
Series Resistance of CVH for
stability
No-load Voltage VH
mA
30
Charging Capacitor at VH
V0(VH)
0
1
R(CVH )
311
V
V
µF
-25
CVH
No-load Voltage VH
5.25
3.465
35
307
V0(VH)
V
4.7
306
310
5.00
3.30
36
4.7
µF
12
I(VCC) + I(VCCA) = -200 mA
Tj = 27 °C
Ω
kHz
120
kHz
kHz
7.5
V
V
5.8
90
WD, WDB, WDC;
I(VCC) = 0, I(VCCA) = 0, VB = 36 V
Tj = 27 °C
7
WDA;
I(VCC) = 0, I(VCCA) = 0, VB = 36 V
Tj = 27 °C
5.4
V
V
6.3
V
V
WD, WDB, WDC;
I(VCC) + I(VCCA) = -200 mA, VB = 8 V
Tj = 27 °C
6
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 5/12
ELECTRICAL CHARACTERISTICS
Operating Conditions: VB = 8...36 V, LVH = 220 µH, Ri(LVH) < 2 Ω, CVH = 4.7 µF, RVB = 1 Ω, Tj = -40...125 °C, unless otherwise noted
Item
No.
313
314
Symbol
Parameter
Conditions
Unit
Min.
Vl(VH)
Ioff
Voltage VH with load
Max. Cut-off Current in VHL
WDA;
I(VCC) + I(VCCA) = -200 mA, VB = 8 V
Tj = 27 °C
VH < Vl(VH), RVB = 1 Ω
Typ.
Max.
4.5
V
V
5.0
-500
-460
-400
mA
150
°C
Error Detection NER
401
Toff
Thermal Shutdown Threshold
130
402
Thys
Thermal Shutdown Hysteresis
3
15
°C
403
∆VCC
∆VCCA
Relative Undervoltage Threshold
at VCC, VCCA referenced to
VCCnom , VCCAnom
8
12
16
%
404
VCChys
VCCAhys
Undervoltage Hysteresis
referenced to VCCnom , VCCAnom
2
4
7
%
405
406
Vs(NER)
Saturation Voltage lo at NER
I(NER) = 5 mA
Isc(NER)
Short-Circuit Current lo in NER
V(NER) = 1...36 V
Tj = -40 °C
Tj = 27 °C
Tj = 70 °C
Tj = 125 °C
5
NER = off, V(NER) = 0...36 V
0
407
I0(NER)
Collector Off-State Current in
NER
0.7
V
21
mA
mA
mA
mA
mA
10
µA
15
12
10
8
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 6/12
DESCRIPTION OF FUNCTIONS
Vsat
VB
V(LVH)
LVH
S
cillator frequency is reduced as the level of voltage VH
rises (Fig. 5).
500mV
400mV
∆VR = VB − VBR
Fig. 1 illustrates the operating principle of the switching
converter in simplified form. When the switch S closes
in steady-state condition, a linearly increasing charging current for the capacitor CVH flows through the coil
LVH in addition to the load current in RL . The energy
from the supply VB is stored in the coil’s magnetic field.
When the switch opens, the current flows via the diode
through the coil; its energy content is supplied to capacitor and load.
300mV
200mV
typ.
VH
100mV
CVH
VD
RL
0V
6.0V
5.5V
6.5V
7.0V
7.5V
VH
Figure 2: Regulating characteristic ∆VR = f (VH)
Figure 1: Principle of operation
1.5V
The current rise (tr ) and fall times (tf ) depend on the
voltage VH at the inductor. The following approximation applies:
max.
1.0V
Vsat = VB − VHL
The block diagram on page 1 shows the iC-WD with
typical wiring. The internally generated clock pulse
closes the switch between VBR and VHL and the current in the coil rises (charging phase). A control variable, ∆VR in accordance with the regulating characteristic in Fig. 2, is obtained from the voltage VH and
the internal reference voltage and is compared to the
voltage at shunt RVB . When the cut-off current Ioff =
∆VR /RVB is reached, the switch opens and the coil
current runs free via the integrated power diode (discharge phase). When the next clock signal occurs, this
charging and discharging process is repeated. Fig. 6
shows the resulting current and voltage characteristics.
typ.
0.5V
0V
0A
100mA
200mA
300mA
400mA
500mA
I(VHL)
Figure 3: Saturation voltage of switching transistor
1.5V
Ioff
tr = LVH
VB − Vsat − VH
Ioff
tf = LVH
VH + VD
(1)
max.
1.0V
VD : Forward voltage of the free-wheeling diode
The current dependencies of the saturation and diode
forward voltage (Fig. 3 and 4) are ignored here, as are
the losses due to the internal resistance of the coil.
typ.
VD = − VHL
Vsat = VB − VHL: Saturation voltage of the switching
transistor plus voltage drop at RVB
0.5V
0V
0A
100mA
200mA
300mA
400mA
500mA
I(VHL)
The regulator operates at a constant frequency under
load. To prevent VH from rising without load, the os-
Figure 4: Forward voltage of free-wheeling diode
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 7/12
125kHz
ing mode. Since both the charging and the discharging
current flow in VH, the initial approximation of the mean
current-carrying capacity of VH is:
typ.
100kHz
75kHz
fosz
IL (VH) =
1 tr + tf
I
2 off T
(2)
50kHz
25kHz
T = 1/fosz : Period of internal oscillator (Fig. 5)
0
5.5V
6.0V
6.5V
7.0V
VH
7.5V
Figure 5: Oscillator Frequency
For load current IL at output VH, the iC-WD adjusts the cut-off current Ioff to the following value
(VB > VH + Vsat ):
The following three operating states of the regulator
are described as a function of the supply voltage and
the load current:
s
Ioff =
2 · IL (VH)
T
LVH
1
1
VB−Vsat −VH
1
+ VH+V
(3)
D
Ioff
I(LVH)
Since only during the charging phase current is drawn
from supply voltage VB, the mean current consumption
is: (VB > VH + Vsat ):
I(VB) = Ioff
0
tr
+ I0 (VB)
T
(4)
I0 (VB): current consumption without load at VCC,
VCCA (no-load operation)
VHL
VB
VH
0
tr
tf
T = 1/f osz
Figure 6: Intermittent flow
SWITCHING REGULATOR: Intermittent flow
When charging and discharging operation are concluded within a single clock pulse period (tr + tf < T )
and the coil current drops to zero, intermittent flow prevails (Fig. 6). This is the case when the supply voltage
is sufficiently high or the load current sufficiently low.
The current-carrying capacity and power consumption
of the regulator can be easily specified for this operat-
SWITCHING REGULATOR: Continuous flow
If the inductor receives recharge with the next clock
signal before the coil current has run free, no gap is
created in the current. Such continuous flow (Fig. 7)
occurs when the supply voltage is too low or the load
current too high. Since the charging process begins at
various current levels not equal to zero, the timing and
the required cut-off current are difficult to express. In
general, fluctuations occur in the clock frequency at the
time constants of the charging and discharging phase,
which in turn depend on the of supply voltage and the
load current. Since no current gap occurs, the cut-off
current may be lower than during intermittent flow (at
the same load). The losses in the switching transistor, in the free-wheeling diode and due to the internal
resistance of the inductor are consequently lower; the
efficiency of the regulator is thus higher. In addition, interference due to the internal resistance of supply voltage source and standby capacitor CVH is lower. Depending on the model and quality of the coil, however,
the low frequent fluctuations may be audible.
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 8/12
VH to VCC or VCCA the size of standby capacitor
CVH should be increased for this type of operation (e.g.
22 µF).
Ioff
I(LVH)
SERIES REGULATORS VCC and VCCA
To obtain the lowest possible interference voltage even
with the small smoothing capacitor CVH , two independent series regulators with a NPN emitter follower
stage are connected downstream of intermediate voltage VH. The Output voltages VCC or VCCA are constant ±5%. The suppression of interference voltage for
the output voltages is best when VH is also no lower
than 6.0 V dynamically (iC-WDA: 4.3 V).
0
VB
VHL
The series regulators are compensated internally,
hence they are stable during no-load operation, without external capacitance. Stability over the entire load
range is ensured by the minimum capacitance values
for CVCC and CVCCA given in the electrical characteristics. Current-limited outputs are used as protection
against destruction in the event of a short circuit.
VH
0
tr
T = 1/f osz
Figure 7: Continous flow
SWITCHING REGULATOR: Operation at low supply
voltage
A third operating state occurs when the supply voltage VB is scarcely higher than VH. The cut-off current can no longer be reached in this case since:
(VB − VH − Vsat )/RLVH < Ioff . The switching transistor is switched on continuously and VH reaches: VH =
VB − Vsat − I(VH) × RLVH . Factoring in this special
feature makes it possible to operate the iC-WD even
at low supply voltage. Operability is still guaranteed
at VB ≈ 7.6 V. Nonetheless, the maximum currentcarrying capacity depends on the coil’s internal resistance and supply voltage VB. The transition from
regulator mode to continuously activated transistor is
fluid. To avoid feedback of interference voltage from
FAULT EVALUATION
The two output voltages VCC and VCCA are monitored. When the voltage drops below the undervoltage
threshold (due to overload, etc.), a message is sent
to the current-limited open-collector output NER (active low). The chip temperature is also monitored. In
the event of overtemperature the switching regulator is
turned off and it is not enabled against until the chip
temperature has decreased. This thermal shutdown
of the regulator is indicated by NER = low. Since the
fault output NER is current-limited, an LED can be connected directly for the optical message display, however the additional power dissipation which occurs
Pv = I(NER) × (VB − Vfw (LED))
(5)
must be taken into account. A resistor RLED in series with the LED can reduce the additional chip power
dissipation in the event of a fault. CMOS- or TTLcompatible logic inputs can be activated with a pull-up
resistor at NER.
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 9/12
APPLICATIONS INFORMATION
DIMENSIONING
The size of shunt RVB determines the cut-off current
Ioff . By varying this in combination with the value for
the inductor LVH , the power input, the efficiency and
the timing can be adapted to the application.
Normally the supply voltage range and the maximum
output current for VCC and VCCA is specified. Define
whether or not only intermittent flow is desired. The
maximum inductance LVH can be estimated on the following basis: In the worst situation, charging and discharging process last exactly one period, which is the
case at minimum supply power. The cut-off current adjusts to Ioff = 2 × ILmax (VH). From equation (1) it follows
that:
LVHmax =
Tmin
×
2ILmax (VH)
Using equation (3) it is possible to determine the maximum cut-off current for intermittent flow. The maximum
value for VB must be inserted:
s
2 · ILmax (VH)
Ioffmax =
Tmax
·
LVH
1
+ VH+V
D
The shunt RVB can be dimensioned with this information. ∆VRmax can be obtained from Fig. 2:
1
1
VBmin −Vsat −VH
1
1
VBmax −Vsat −VH
RVB =
1
+ VH+V
D
∆VRmax
Ioffmax
EXAMPLE
Specified are: VB = 18...36 V, ILmax = 100 mA; the maximum inductance can be estimated to:
LVHmax =
1/125 kHz
·
200 mA
1
1
18 V −1.1 V −7.0 V
1
+ 7.0 V +1.1
V
= 178 µH
The inductance selected is 150 µH, for example. Consequently, the maximum required cut-off current and the
shunt are found to be:
s
Ioffmax =
2 · 100 mA
1/75 kHz
·
150 µH
⇒ RVB =
1
1
30 V −1.1 V −7 V
1
+ 7 V +1.1
V
= 324 mA
400 mV
≈ 1.2 Ω
324 mA
It is not always possible to dimension the circuit for intermittent flow, particularly not when high output currents are required with a low supply voltage. Permitting continuous flow may prove conducive to higher
efficiency and less interference. The inductance selected is to be higher than in the above formula; the
equations for maximum cut-off current and the shunt
can be used with the selected coil.
It is simplest to ascertain the correct dimensioning
by experiment in a test set-up (Evaluation Board).
The dimensioning shown in the block diagram (LVH
= 220 µH, RVB = 1 Ω is suitable for maximum performance throughout the entire specification range.
SELECTING THE COMPONENTS
Since the coil must not to become saturated, it should
be designed for maximum cut-off current. This can be
checked by testing the coil current with a current probe:
In the event of saturation the current rises much more
sharply than with low currents. A low internal resistance of the coil reduces the losses and increases the
regulator’s efficiency. When the supply voltage is low,
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 10/12
this internal resistance can determine the maximum
available output current (equation 4).
The EMI (electromagnetic interference) caused by the
coil should be taken into account. Toroidal core coils
have little noise radiation but are expensive and difficult
to install. Bar cores are reasonably priced and easy
to handle but emit higher radiation. Reasonably priced
RF chokes in the range of a few tens to a few hundreds
µH are suitable for modest EMI requirements.∗
Additional interference may be caused by decaying of
the voltage at VHL when the coil current drops to zero
(Fig. 6). Parasitic capacitances at VHL form an oscillating circuit with the coil. This undesirable oscillating
circuit can be damped to an uncritical magnitude by
installing a resistor (> 10 kΩ) parallel to the coil.
The selection of the backup capacitor CVH is unproblematic. Due to the series regulators, the ripple of
the intermediate voltage VH does not affect the output voltages VCC and VCCA. Therefore a low capacitance level without special demands on the internal
resistance is sufficient. A combination of electrolytic
and ceramic capacitor (e.g. 4.7 µF/100 nF) is recommended. Tantalum capacitors are also possible when
they are allowed to operate at AC amplitudes like the
residual ripple of voltage VH.
The stability of the series regulators is guaranteed for
the entire load range when the values for CVCC and
CVCCA given in the electrical characteristics are selected. The suppression of interference voltage is improved by small capacitor series resistors. The combination of tantalum and ceramic capacitors is also recommended in this case. If one of the two outputs remains open, its capacitor can be omitted.
∗
To avoid feedback of interference from supply voltage VB onto output voltages VCC and VCCA, provide
blocking directly at pin VB. A combination of tantalum
and ceramic capacitors is also recommended in this
case (several µF/100 nF).
PRINTED CIRCUIT BOARD LAYOUT
The GND path from the switching regulator and from
each series regulator should be strictly separated to
avoid cross couplings. The neutral point of all GND
conductors is the GND connection at the iC-WD. It is
possible and not critical, however, to route the GND of
the supply VB and the base point of capacitor CVH together to the neutral point. The capacitor CVH should
be very close to the pin VH however. To keep down the
decay at the open end of the coil (pin VHL), the capacitance of this connection should be low, that means the
connection should be short.
The blocking capacitors of supply voltage VB are to be
placed as close as possible to pins VB and GND. The
capacitors for the outputs VCC and VCCA should be
placed directly by the load and not directly by the iC
to also block interferences which are coupled via the
wiring to the load. A ground plane should be cut out
underneath the wiring of CVCC and CVCCA . The printed
circuit conductor between VB, the shunt RVB, and VBR
should have a low impedance, since voltage drops in
the supply path change the effective size of the shunt
and reduce the maximum cut-off current.
The Thermal Pad (optional with the SO8) should be
connected to an appropriate copper area on the PCB.
It has proven to be advantageous to use thermal vias
directly underneath the iC to transfer the power dissipation to a different layer, e.g. a ground plane.
e.g.: Siemens Matsushita B78108-S1224-J (220 µH/250 mA, axial leads), TDK series NLC565050T-. . . (SMD),
TOKO series 10RF459-. . . (SMD shielded)
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 11/12
EVALUATION BOARD
For the iC-WD devices an Evaluation Board is available for test purpose. The following figures show
the schematic as well as the layout of the Evaluation
Board.
RVB
LVH
VH
VB
CVB
1Ω
8
4.7 µF
GND
220 µH
2
VB
VBR
3
CVH
4.7 µF
5
VHL
VH
RNER
1.2 kΩ
SWITCHING REGULATOR VH
DNER
LED
OSCILLATOR
VCC
6
VCC
CVCC
NER
1
NER
4.7 µF
THERMAL
GND
REG VCC
SHUTDOWN
LOW VOLTAGE
ERROR DETECTION
iC−WD
REFERENCE
VCCA
7
VCCA
CVCCA
VREF
1 µF
REG VCCA
GND
GND
4
Figure 8: Schematic diagram of the Evaluation Board
Figure 9: Evaluation Board (components side)
This specification is for a newly developed product. iC-Haus therefore reserves the right to change or update, without notice, any information contained herein,
design and specification; and to discontinue or limit production or distribution of any product versions. Please contact iC-Haus to ascertain the current data.
Copying – even as an excerpt – is only permitted with iC-Haus approval in writing and precise reference to source.
iC-Haus does not warrant the accuracy, completeness or timeliness of the specification on this site and does not assume liability for any errors or omissions
in the materials. The data specified is intended solely for the purpose of product description. No representations or warranties, either express or implied, of
merchantability, fitness for a particular purpose or of any other nature are made hereunder with respect to information/specification or the products to which
information refers and no guarantee with respect to compliance to the intended use is given. In particular, this also applies to the stated possible applications or
areas of applications of the product.
iC-Haus conveys no patent, copyright, mask work right or other trade mark right to this product. iC-Haus assumes no liability for any patent and/or other trade
mark rights of a third party resulting from processing or handling of the product and/or any other use of the product.
iC-WD A/B/C
SWITCHED-MODE DUAL VOLTAGE REGULATOR
Rev D1, Page 12/12
ORDERING INFORMATION
Typ
(VCC/VCCA)
Package
Order Designation
SO8
SO8 thermal pad
DFN10 (on request)
iC-WD SO8
iC-WD SO8-TP
iC-WD DFN10
Evaluation Board iC-WD
-
iC-WD EVAL WD2D
iC-WDA
DFN10
iC-WDA DFN10
Evaluation Board iC-WDA
-
iC-WDA EVAL WD2D
iC-WDB
DFN10
iC-WDB DFN10
Evaluation Board iC-WDB
-
iC-WDB EVAL WD2D
iC-WDC
DFN10
iC-WDC DFN10
-
iC-WDC EVAL WD2D
iC-WD
(5/5 V)
(3.3/3.3 V)
(3.3/5 V)
(5/3.3 V)
Evaluation Board iC-WDC
For technical support, information about prices and terms of delivery please contact:
iC-Haus GmbH
Am Kuemmerling 18
D-55294 Bodenheim
GERMANY
Tel.: +49 (61 35) 92 92-0
Fax: +49 (61 35) 92 92-192
Web: http://www.ichaus.com
E-Mail: [email protected]
Appointed local distributors: http://www.ichaus.de/support_distributors.php