Trimming circuit and semiconductor device
View Patent ↗Provided are a trimming circuit which does not need a dedicated terminal to which a current for cutting a fuse is input, and also a semiconductor device including the trimming circuit. The trimming circuit includes: an input terminal connected to a pad which is an external terminal of an internal circuit; a fuse provided between a power supply terminal and an output terminal; and a diode provided between the input terminal and the output terminal. The trimming circuit performs trimming by applying, to the pad, such a voltage that the diode is biased in the forward direction.
1. A trimming circuit for trimming a resistor circuit, the resistor circuit including a plurality of resistors connected in series between a power supply terminal and a ground terminal, the trimming circuit comprising:
an input terminal connected in common to a pad that comprises an external terminal of an internal circuit;
an output terminal connected to the resistor circuit;
a fuse directly connected to the output terminal and connected in parallel to a selected resistor of the plurality of resistors of the resistor circuit, the fuse and the selected resistor directly connected to either the power supply terminal or to the ground terminal; and
a reverse biased diode directly connected to the input terminal and to the fuse,
wherein the trimming circuit trims the resistor circuit by applying a voltage to the pad, such that a current flows from the pad to the power supply terminal or to the ground terminal only via the fuse and the reverse biased diode is biased in a forward direction.
2. A trimming circuit according to claim 1 , further comprising:
a second output terminal connected to the resistor circuit;
a second fuse which is provided between the second power supply terminal and the second output terminal and is connected in parallel to another one of the plurality of resistors of the resistor circuit; and
a second diode provided between the input terminal and the second output terminal,
wherein the trimming circuit performs trimming by applying, to the pad, one of such a voltage that the first diode is biased in the forward direction and such a voltage that the second diode is biased in the forward direction.
3. A trimming circuit according to claim 1 further comprising:
a second trim circuit having a second input terminal connected to a second pad and a second output terminal connected to the resistor circuit, the second trim circuit including,
a fuse directly connected to the second output terminal and connected in parallel to a second selected resistor of the plurality of resistors of the resistor circuit, the fuse and the second selected resistor directly connected to the ground terminal and a reverse biased diode directly connected to the second input terminal and to the fuse.
4. A trimming circuit comprising:
a resistor circuit including a plurality of resistors connected in series between a first power supply terminal and a second power supply terminal, the trimming circuit further comprising:
an input terminal connected in common to a pad which is an external terminal of an internal circuit;
an output terminal connected to the resistor circuit;
a fuse between the first power supply terminal and the first output terminal and connected in parallel to one of the plurality of resistors of the resistor circuit; and
a diode provided between the input terminal and the first output terminal;
a current limiting resistor connected between the input terminal and the first output terminal and in series with the diode,
wherein the trimming circuit performs trimming by applying, to the pad, such a voltage that the diode is biased in a forward direction.
5. A semiconductor device comprising:
a resistor circuit including a plurality of series-connected resistors;
an internal circuit having a predetermined function;
a pad connected to the internal circuit, the pad comprising an external terminal; and
a trimming circuit comprising:
an input terminal connected in common to the pad;
an output terminal connected to the resistor circuit;
a fuse directly connected to the output terminal and connected in parallel to a selected resistor of the plurality of resistors of the resistor circuit, the fuse and the selected resistor directly connected to either the power supply terminal or to the ground terminal; and
a reverse biased diode directly connected to the input terminal and to the fuse,
wherein the trimming circuit trims the resistor circuit by applying a voltage to the pad, such that a current flows from the pad to the power supply terminal or to the ground terminal only via the fuse and the reverse biased diode is biased in a forward direction.