JP3772727B2 - Semiconductor integrated circuit device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor integrated circuit device such as a power supply control CMOS-IC used for various power supplies requiring power factor improvement.
[0002]
[Prior art]
In various power supplies that require power factor improvement, such as refrigerators and air conditioners, a large negative input voltage exceeding -5V is applied to the power control IC mounted on the power supply when the power supply is started. May be entered. However, during steady operation, a small negative voltage of about -1V to 0V is input.
[0003]
FIG. 3 is a principal circuit diagram of a conventional power supply control bipolar IC. One end of the resistor R4 is connected to the high potential side VCC of the power supply, the other end of the resistor R4 is connected to one end of the resistor R5, the other end of the resistor R5 is connected to the negative voltage input terminal 13, and the resistors R4 and R5 The connection point B is connected to the base of the pnp bipolar transistor of the control circuit 12.
Normally, even if a negative voltage is input to the negative voltage input terminal 13, the resistance values of the resistors R4 and R5 are determined so that the potential at the point B becomes a positive voltage. The resistors R4 and R5 are diffusion resistors formed by diffusion (the p layer in FIG. 4).
[0004]
However, as described above, when a large negative voltage is applied to the negative voltage input terminal 13 at the time of starting the power source, the potential at the point B also becomes a large negative voltage and passes through the base from the collector connected to the ground of the pnp transistor. A current flows toward the negative voltage input terminal 13 through the resistor R5. However, the current may be limited by the resistor R5, and the pnp transistor is not destroyed. The breakdown does not occur unless the reverse resistance of the pn junction by the diffusion resistance and the n epitaxial layer is exceeded. Actually, since the reverse breakdown voltage of the pn junction (see FIG. 4) shown in FIG. 4 is as high as about −80 V, no breakdown occurs.
[0005]
However, since this bipolar IC for power control uses a bipolar transistor which is a current driving element, it is difficult to reduce power consumption and speed.
In the future, in order to realize low power consumption and high speed, it will be necessary to miniaturize the unit elements constituting the power control IC, and the power control CMOS-IC composed of MOSFETs (CMOS is a MOSFET) Complementary circuit configured) is considered to be the standard.
[0006]
[Problems to be solved by the invention]
However, in the power supply control CMOS-IC configured by this MOSFET, when a large negative voltage is input, a large negative voltage is applied between the source and gate of the p-channel MOSFET in the input section, and the gate insulation of the p-channel MOSFET. The film causes dielectric breakdown, and the p-channel MOSFET is destroyed.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor integrated circuit device such as a power supply control CMOS-IC capable of inputting a negative voltage.
[0008]
[Means for Solving the Problems]
To achieve the above object, in a semiconductor integrated circuit device that operates using a negative voltage as an input signal, a level shift circuit that converts the negative voltage to a positive voltage by dividing a plurality of resistors, and an output from the level shift circuit And a control circuit composed of a MOSFET that operates as an input signal.
[0009]
The level shift circuit includes: a first resistor having one end connected to the high potential side of the power supply; a second resistor connected to the other end of the first resistor; and the other end of the second resistor; A first diode connected to the anode; a cathode of the first diode connected to a ground side of a power supply; a third resistor connected at one end to a connection point between the second resistor and the anode of the diode; A negative voltage input terminal connected to the other end of the resistor, a second diode having a cathode connected to a connection point of the first resistor and the second resistor, and an anode of the second diode connected to the ground side of the power source, An output terminal connected to a connection point of the first resistor and the second resistor is provided.
[0010]
The first resistor, the second resistor, and the third resistor may be formed of polysilicon.
In a semiconductor integrated circuit device that operates using a negative voltage as an input signal, a control circuit composed of CMOS is selectively formed on the surface layer of the first conductivity type semiconductor substrate, and the control is formed on the surface layer of the semiconductor substrate. Second conductivity type first well region and second well region formed apart from the circuit, at least one first conductivity type third well region formed in the first well region, and the third well At least one first-conductivity-type first cathode region and first-conductivity-type first anode region of the first diode formed on the surface layer of the region, and at least one formed on the surface layer of the second well region. A conductive type fourth well region; a second conductive type second cathode region of a second diode; a first conductive type second anode region; and a first conductive type second anode region formed on a surface layer of the fourth well region. First conductivity type second diffusion A second diffusion region of a second conductivity type formed in the surface layer of the second well region, and a first resistor, a second resistor formed independently on the semiconductor substrate via an insulating film, A third resistor,
A first resistor having one end connected to the high potential side of the power supply, a second resistor connecting the other end and one end of the first resistor, the other end of the second resistor, one end of the third resistor, and the first Connected to the anode region, connected to the other end of the resistor and the negative voltage input terminal, connected to the first cathode region and the ground of the power source, connected to one end of the second resistor and the second cathode region, and second anode A connection point between the first resistor and the second resistor, a first cathode region and the first diffusion region, a second cathode region and a second diffusion region, and a connection point between the first resistor and the second resistor; And an input point of the control circuit.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a principal circuit configuration diagram of a semiconductor integrated circuit device according to the present invention. Here, the power supply control CMOS-IC 100 including the level shift circuit 1 and the control circuit 2 is taken as an example. The control circuit 2 is mainly composed of a CMOS-IC circuit (not shown) composed of a MOSFET.
[0012]
The high potential side VCC of the power supply is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to one end of the resistor R3 and the anode of the Zener diode ZD1. The other end of the resistor R3 is connected to the negative voltage input terminal 3, the cathode of the Zener diode ZD1 is connected to the anode of the Zener diode ZD2, the cathode of the Zener diode ZD2 is connected to the ground GND of the power source, and the resistor R1 and the resistor R2 Is connected to the cathode of the Zener diode ZD3, and the anode of the Zener diode ZD3 is connected to the ground GND of the power source. The point A becomes an output point of the level shift circuit 1 indicated by a dotted line, and this output point and the input of the control circuit 2 are connected. The level shift circuit 1 and the control circuit 2 constitute a power supply control CMOS-IC 100.
[0013]
From the high potential side VCC of the power source to the negative voltage input terminal 3, it is constituted by a resistor R1, a resistor R2, and a resistor R3. By inputting the voltage at point A to the control circuit 2, a level shift to a positive voltage is made. For the resistors R1, R2, and R3, when a negative voltage is input, a polysilicon resistor is used instead of a diffused resistor in order to prevent a current from the semiconductor substrate. Further, the configuration of the Zener diode ZD1, the Zener diode ZD2, and the resistor R3 prevents overcurrent from flowing from the ground GND toward the negative voltage input terminal 3 when a negative voltage is input to the negative voltage input terminal 3. . Note that the number of Zener diodes is determined by the magnitude of the negative voltage, and may be one when the negative voltage is low, or two or more when the negative voltage is high.
[0014]
Further, the Zener diode ZD3 has a function of clamping the potential at the point A to −0.6 V when a larger negative voltage is input and the potential at the point A becomes a negative voltage.
Now, the conditions under which the voltage at point A becomes a positive voltage when a negative voltage is input will be described.
A point voltage = (VCC + Vin absolute value) × (R2 + R3) / (R1 + R2 + R3) −Vin absolute value> 0 (1)
Here, VCC is the voltage of the high potential side VCC of the power supply, R1, R2, and R3 are the resistance values of the resistors R1, R2, and R3, and the Vin absolute value is the absolute value of the input voltage Vin of the negative voltage input terminal 3. .
R1, R2, and R3 are determined so that the point A voltage becomes a positive voltage. An example is described next.
When Vcc = 5 V and Vin is −1 V (5+ (absolute value of −1)) × (R2 + R3) / (R1 + R2 + R3) − (absolute value of −1) = 6 × (R2 + R3) / (R1 + R2 + R3) −1> 0
That is, (R2 + R3) / (R1 + R2 + R3)> 1/6 (2)
It becomes. The values of R1, R2, and R3 that satisfy this equation (2) are determined.
[0015]
For example, if R1 = 15 kΩ, R2 = 2 KΩ, and R3> 1 kΩ, the voltage at point A can be a positive voltage. Of course, there are various combinations of R1, R2, and R3.
FIG. 2 is a cross-sectional view of a main part of a semiconductor integrated circuit device according to the second embodiment of the present invention. This principal part sectional drawing is a sectional view of the level shift circuit part of FIG.
[0016]
A first n well region 11 and a second n well region 12 are formed on the surface layer of the p ⁻ substrate 10, and two first p well regions 13 and a second p well region 14 are formed on the surface layer of the first n well region 11. The n ⁺ cathode regions 16 and 18 and the p ⁺ anode regions 17 and 19 of the Zener diodes ZD1 and ZD2 are formed in the first and second p well regions 13 and 14, respectively. A third p well region 15 is formed in the surface layer of the second n well region 12, and an n ⁺ cathode region 20 and a p ⁺ anode region 21 of the Zener diode ZD3 are formed in the surface layer of the third p well region 15.
[0017]
Further, in order to fix the potentials of the first and second well regions 11 and 12, the first p well region, the second p well region, and the third p well region are formed on the surface layers of the first n well region 11 and the second n well region 12, respectively. And n ⁺ regions 22 and 23 are formed.
Alternatively, the first n-well region 11 may be divided into two n-well regions, and one zener diode (ZD1 or ZD2) may be formed in each n-well region.
[0018]
Further, an insulating film 24 is selectively covered on the surface of the p ⁻ substrate 10, and a polysilicon resistor 25 serving as a resistor R 1, a resistor R 2, and a resistor R 3 is formed thereon. This insulating film 24 may be a selective oxide film.
The high potential side VCC of the power supply is connected to one end of the resistor R1, the other end is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R3, and the other end is connected to the negative voltage input terminal 3. Then, one end of the resistor R3 is connected to the p ⁺ anode region 19 of the Zener diode Z1, connected to the n ⁺ cathode region 18 and the p ⁺ anode region 17 of the Zener diode ZD2, and the n ⁺ cathode region 16 and the n ⁺ region 22 The n ⁺ region 22 and the ground GND are connected, the p ⁺ anode 21 of the Zener diode ZD3 and the ground are connected, and the n ⁺ cathode 20 and the n ⁺ region 23 of the Zener diode ZD3 and one end of the resistor R2 are connected. This connection point is point A. Of course, the control circuit 2 is also formed on the p ⁻ substrate 10.
[0019]
Thus, the same semiconductor substrate ^- the (p substrate 10), the control circuit by integrating 2 and level shift circuit 1, it is possible to reduce the size and manufacturing cost.
Of course, a region of the opposite conductivity type may be formed on the p ⁻ substrate.
[0020]
【The invention's effect】
According to the present invention, since the level shift circuit for converting a negative voltage input signal into a positive voltage is provided, even when a negative voltage input signal is applied, the gate insulating film of the integrated MOSFET is not destroyed. Therefore, a MOSFET can be employed in a semiconductor integrated circuit such as power supply control, and low power consumption and high speed can be achieved.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of the main part of a semiconductor integrated circuit device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the main part of a semiconductor integrated circuit device according to a second embodiment of the present invention. Main circuit diagram of bipolar IC for control [Figure 4] Diagram of diffused resistor [Explanation of symbols]
1 level shift circuit 2 control circuit 3 the negative voltage input terminal 10 p ^- substrate 11 first 1n-well region 12 a 2n-well region 13 a 1p-well region 14 a 2p-well region 15 a 3p-well region 16, 18, 20 n ⁺ cathode region 17, 19, 21 p ⁺ anode region 22, 23 n ⁺ region 24 insulating film 25 polysilicon resistor 100 power supply control IC
High potential side of VCC power supply / power supply voltages R1, R2, R3 Resistance / resistance values ZD1, ZD2, ZD3 Zener diode Vin Negative voltage input terminal / input voltage GND Ground

Claims (3)

In a semiconductor integrated circuit device that operates using a negative voltage as an input signal, it is composed of a level shift circuit that converts the negative voltage to a positive voltage by dividing a plurality of resistors, and a MOSFET that operates using the output of the level shift circuit as an input signal. The level shift circuit includes a first resistor having one end connected to the high potential side of the power supply, a second resistor connected to the other end and one end of the first resistor, and the second resistor The other end of the two resistors, the first diode to which the anode is connected, the cathode of the first diode is connected to the ground side of the power source, and one end is connected to the connection point of the second resistor and the anode of the diode. Three resistors, a negative voltage input terminal connected to the other end of the third resistor, a second diode having a cathode connected to a connection point of the first resistor and the second resistor, and an anode of the second diode being a power source Connected to the ground side, the semiconductor integrated circuit device characterized by comprising an output terminal connected to the connection point of the first resistor and the second resistor. 2. The semiconductor integrated device according to claim 1 , wherein the first resistor, the second resistor, and the third resistor are formed of polysilicon. In a semiconductor integrated circuit device that operates using a negative voltage as an input signal, a control circuit composed of CMOS is selectively formed on a surface layer of a first conductivity type semiconductor substrate, and the control circuit and the control circuit are formed on the surface layer of the semiconductor substrate. A second well-type first well region and a second well region formed separately, at least one first-conductivity-type third well region formed in the first well region, and the third well region A first conductivity type formed on the surface layer of the second well region and a first conductivity type first cathode region, a first conductivity type first anode region of the first diode formed on the surface layer, and the second well region. A fourth well region, a second conductivity type second cathode region and a first conductivity type second anode region of a second diode formed on a surface layer of the fourth well region, and the first well region. A first diffusion region of a second conductivity type; A second diffusion region of the second conductivity type formed in the surface layer of the second well region, and a first resistor, a second resistor, and a third resistor formed independently on the semiconductor substrate via an insulating film And
A first resistor having one end connected to the high potential side of the power supply, a second resistor connecting the other end and one end of the first resistor, the other end of the second resistor, one end of the third resistor, and the first Connected to the anode region, connected to the other end of the resistor and the negative voltage input terminal, connected to the first cathode region and the ground of the power source, connected to one end of the second resistor and the second cathode region, and second anode A connection point between the first resistor and the second resistor, a first cathode region and the first diffusion region, a second cathode region and a second diffusion region, and a connection point between the first resistor and the second resistor; And an input point of the control circuit are connected to each other.

Images