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Description  |
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This invention relates to an integrated driving circuit that can control
high voltage and power and, more particularly, to a high voltage and power
driving circuit employing BiCMOS technology.
High voltage and power driving circuits are widely used in motor- and
speaker-driving circuits.
The conventional driving circuit usually employs CMOS IC (integrated
circuit) or bipolar circuits. In a CMOS IC driving circuit, a large signal
swing can be obtained using MOS transistors, which have a high breakdown
voltage between drain and source, but it is difficult to drive large
currents, i.e. provide high powers, due to low transconductance (gm) of
the MOS transistors. In a driving circuit using bipolar circuits, in very
large scale integration (VLSI), the transistors can handle large currents,
but it is difficult to obtain a large signal swing, due to limited
breakdown voltage between collector and emitter (LVCEO).
SUMMARY OF THE INVENTION
The principal object of the invention is, therefore, to provide an
integrated high voltage and high power driving circuit, which is also
reliable, by using BiCMOS technology, without external discrete
components.
Another objective of the invention is to provide a circuit with a reduced
number of external components, outside an integrated-circuit chip, by
which loads are driven to high voltage and power.
BRIEF DESCRIPTION OF THE DRAWING
Detailed descriptions of the invention are given with reference to a
drawing, wherein:
FIG. 1 is a circuit diagram of an embodiment of the invention; and
FIG. 2 is a circuit diagram of another, extended embodiment of the
invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
FIG. 1 is a circuit diagram of an embodiment of the invention where R.sub.1
-R.sub.7 and R.sub.L are resistors, Q.sub.1XN -Q.sub.4XN are bipolar
transistors, I.sub.1 -I.sub.2 are inverters, M.sub.1 -M.sub.6 are high
voltage MOS transistors, and D.sub.1 -D.sub.2 are diodes. The four bipolar
transistors shown are paired in two Darlington circuits, but the number of
transistors actually in each Darlington circuit may be multiplied by an
integer N, as indicated by the subscripts of their reference characters in
keeping with a known referencing scheme, depending upon the current value
to be obtained, as known for Darlington circuits.
In the circuit of FIG. 1, a large-current driving section 10 receives a
CMOS-level signal from input port 1 at the gate of a high-voltage MOS
transistor M.sub.1. The drain node 2 of said high voltage MOS transistor
M.sub.1 is connected to a voltage supply port 2LVCEO (shown in duplicate
in FIG. 1 for clarity) through a resistor R.sub.1. Two bipolar transistor
Q.sub.1XN, Q.sub.2XN are cascaded as at least one Darlington pair with an
input base also connected to the drain node 2 of the high voltage MOS
transistor M.sub.1 to supply a large current to node 3 for a load R.sub.L.
In a delay section 20, the input port of an inverter I.sub.1 is also
connected to the CMOS-level signal input port 1. The output port of the
inverter I.sub.1 is connected to the input port of another inverter
I.sub.2, which also has an output port.
In a load driving section 30 the output port of the other inverter I.sub.2,
i.e. of said delay section 20, is connected to the gate of a high voltage
MOS transistor M.sub.6. The drain node 5 of said high voltage MOS
transistor M.sub.6 is connected to the voltage supply port 2LVCEO through
load resistor R.sub.7 and to the anode of a diode D.sub.1. The cathode of
said diode D.sub.1 is connected to the anode of another diode D.sub.2, and
the cathode of diode D.sub.2 is connected to the input base of another
Darlington pair of transistors Q.sub.3XN, Q.sub.4XN, which are cascaded to
augment the supply of the large current from the node 3 to a node 7 and
the load, which is, in this case, resistor R.sub.L.
In a reference voltage generation section 40, two sets of series-connected
resistors R.sub.4, R.sub.5 and R.sub.2, R.sub.3 are connected in parallel.
One end of the parallel sets of resistors (node 9) is connected to the
voltage supply port 2LVCEO and the other end, is connected to ground.
In a reference voltage transport section 50, the CMOS-level signal input
port 1 is connected to the gate of a high voltage MOS transistor M.sub.5.
The source of the high voltage MOS transistor M.sub.5 is connected to
ground, and the drain of the high voltage MOS transistor M.sub.5 is
connected to a node 4. The node 4 is connected to a center node 8 of the
serially connected resistors R.sub.4, R.sub.5 of the reference voltage
generation section 40 through a resistor R.sub.6 of the reference voltage
transport section 50 and the gate of another high voltage MOS transistor
M.sub.2 (more precisely a PMOS path transistor) also of the latter. The
drain of the other high voltage MOS transistor M.sub.2 is connected to a
center node 6 of the serially connected resistor R.sub.2, R.sub.3 of the
reference voltage generation section 40, and the source of the other high
voltage MOS transistor M.sub.2 is connected to the node 3. The node 3 is
connected to the output port of the second-in-cascade bipolar transistor
Q.sub.2XN of the large-current driving section 10, as well as to the
collectors of the bipolar transistors Q.sub.3XN, Q.sub.4XN of the load
driving section 30, as previously described.
The operation of the embodiment of the invention of FIG. 1 is, therefore,
explained in detail as follows:
When a CMOS-level, i.e. low-voltage, low-current input signal is applied to
the CMOS-level signal input port 1 and logic-state swings from a "0" to a
"1", for example, the voltage at the node 7 for the external load R.sub.L
swings from 2LVCEO --4V BE volt to 0 volt with the bipolar transistors
Q.sub.2XN, Q.sub.4XN together providing a large current supply at the
former voltage.
In other words, on the one hand, when a logic level "0" signal is applied
to the CMOS-level signal input port 1, the high voltage MOS transistor
M.sub.1 turns off and the voltage at its drain node 2 goes to 2LVCEO. This
2LVCEO voltage turns on the bipolar transistors Q.sub.1XN, Q.sub.2XN to
node 3. The logic level "0" signal is also applied to the inverters
I.sub.1, I.sub.2, and after passing through these, is applied to the high
voltage MOS transistor M.sub.6, which turns off the high voltage MOS
transistor M.sub.6. The voltage at the drain node 5 of the high voltage
MOS transistor M.sub.6 then goes to 2LVCEO. This voltage turns on the
diodes D.sub.1, D.sub.2 and the bipolar transistors Q.sub.3XN, Q.sub.4XN
so that current flows in the load R.sub.L from node 3 through the
transistors Q.sub.3XN, Q.sub.4XN. Then, the voltage at the node 7 to the
external load R.sub.L is 2LVCEO--4V BE volt.
On the other hand, when a logic level "1" signal is applied to the
CMOS-level signal input port 1 and, thus, the high voltage MOS transistor
M.sub.1, the high voltage MOS transistor M.sub.1 turns on the MOS voltage
at its drain node 2 goes to O volt. This turns off the bipolar transistors
Q.sub.1XN, Q.sub.2XN. The logic level "1" signal is also applied to the
inverters I.sub.1, I.sub.2, and after passing through these, is applied to
the high voltage MOS transistor M.sub.6, which turns on the high voltage
MOS transistor M.sub.6. The voltage at the drain node 5 of the high
voltage M.sub.6 goes to O volt. This turns off the diodes D.sub.1, D.sub.2
and the bipolar transistors Q.sub.3XN, Q.sub.4XN so that no current flows
in the load R.sub.L. Then, the voltage across the load R.sub.L and, thus,
at the node 7 becomes O volt.
As stated above, when the "1" signal to the CMOS-level signal input port 1,
the bipolar transistors Q.sub.2XN, Q.sub.4XN turn off, and the node 3
therefore goes to certain low voltage. When the voltage at the node 3 is
less than LVCEO (i.e., 2LVCEO/2 and half of the applied voltage),
breakdown of the bipolar transistor Q.sub.2XN would occur, and when
greater, e.g. with the "0" signal, breakdown of the bipolar transistor
Q.sub.4XN would occur.
To prevent such breakdown, i.e. maintain the voltage at the node 3 to be
LVECO, the high voltage MOS transistor M.sub.5 and PMOS path transistor
M.sub.2 are used. Thus, the "1" signal applied to the CMOS-level signal
input port 1 is also applied to the high voltage MOS transistor M.sub.5 to
turn it on. This drops the voltage at the node 4 to O volt. This voltage,
which is applied to the MOS transistor M.sub.2, transfers the voltage at
the node 6 to the node 3. When the registors R.sub.2 -R.sub.5 are R.sub.2
=R.sub.3 =R.sub.4 =R.sub.5, LVCEO voltage is so transferred to the node 3,
and breakdown of the bipolar transistors Q.sub.2XN, Q.sub.4XN is
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