Driving device
A driving device comprises a first transistor (B 13 ), a second transistor (B 14 ), and a resistance element. The first transistor (B 13 ) has one terminal receiving a pulsed current and a control terminal connected to the one terminal. The second transistor (B 14 ) has one terminal connected to at least one load, the other terminal connected to a reference potential together with the other terminal of the first transistor (B 13 ), and a control terminal connected to the control terminal of the first transistor (B 13 ). The resistance element is connected between the control terminal of the first transistor (B 13 ) and the other terminal of the first transistor (B 13 ).
1. A load driver comprising:
a voltage step-up and -down DC/DC converter controller block which controls a voltage step-up and -down DC/DC converter that generates from an input voltage an output voltage and feeds the output voltage to a load; and
a current driver block which generates an output current of the load, wherein
the voltage step-up and -down DC/DC converter comprises:
a first switch of which a first terminal is connected to an application terminal of the input voltage;
a first diode of which a cathode is connected to a second terminal of the first switch and of which an anode is connected to a ground terminal;
an inductor of which a first terminal is connected to the second terminal of the first switch;
a second switch of which a first terminal is connected to a second terminal of the inductor and of which a second terminal is connected to the ground terminal;
a second diode of which an anode is connected to the second terminal of the inductor and of which a cathode is connected to a first terminal of the load; and
a capacitor of which a first terminal is connected to the application terminal of the input voltage and of which a second terminal is connected to the ground terminal.
2. The load driver according to claim 1 , wherein the voltage step-up and -down DC/DC converter controller block comprises:
a reference voltage generation portion arranged to generate a reference voltage from the input voltage; and
a driver arranged to turns the second switch on and off, the reference voltage being fed into the driver.
3. The load driver according to claim 1 , wherein the current driver block comprises:
a current set portion which generates a reference current; and
a constant-current driver which generates the output current based on the reference current.
4. The load driver according to claim 3 , wherein the current set portion outputs a reference voltage based on the reference current to the constant-current driver, and the constant-current driver generates the output current by repeating voltage/current conversion and current/voltage conversion based on the reference voltage.
5. The load driver according to claim 4 , wherein the constant-current driver comprises a plurality of trimmable resistors for the voltage/current conversion and current/voltage conversion.
6. The load driver according to claim 5 , wherein paired ones of the plurality of resistors are disposed in a staggered layout.
7. The load driver according to claim 3 , wherein the current set portion sets the reference current based on a value of whichever is lower of a control voltage fed in externally and a constant voltage previously determined internally.
8. A load driver comprising:
a voltage step-up and -down DC/DC converter controller block which controls a voltage step-up and -down DC/DC converter that generates from an input voltage an output voltage and feeds the output voltage to a load; and
a current driver block which generates an output current of the load, wherein
the voltage step-up and -down DC/DC converter comprises:
a first switch of which a first terminal is connected to an application terminal of the input voltage;
a first diode of which a cathode is connected to a second terminal of the first switch and of which an anode is connected to a ground terminal;
an inductor of which a first terminal is connected to the second terminal of the first switch;
a second switch of which a first terminal is connected to a second terminal of the inductor and of which a second terminal is connected to the ground terminal;
a second diode of which an anode is connected to the second terminal of the inductor and of which a cathode is connected to a first terminal of the load; and
a ceramic capacitor of which a first terminal is connected to the cathode of the second diode and of which a second terminal is connected to the ground terminal.
9. The load driver according to claim 8 , wherein the voltage step-up and -down DC/DC converter controller block comprises:
a reference voltage generation portion arranged to generate a reference voltage from the input voltage; and
a driver arranged to turns the second switch on and off, the reference voltage being fed into the driver.
10. The load driver according to claim 8 , wherein the current driver block comprises:
a current set portion which generates a reference current; and
a constant-current driver which generates the output current based on the reference current.
11. The load driver according to claim 10 , wherein the current set portion outputs a reference voltage based on the reference current to the constant-current driver, and the constant-current driver generates the output current by repeating voltage/current conversion and current/voltage conversion based on the reference voltage.
12. The load driver according to claim 11 , wherein the constant-current driver comprises a plurality of trimmable resistors for the voltage/current conversion and current/voltage conversion.
13. The load driver according to claim 12 , wherein paired ones of the plurality of resistors are disposed in a staggered layout.
14. The load driver according to claim 10 , wherein the current set portion sets the reference current based on a value of whichever is lower of a control voltage fed in externally and a constant voltage previously determined internally.
15. A load driver comprising:
a voltage step-up and -down DC/DC converter controller block which controls a voltage step-up and -down DC/DC converter that generates from an input voltage an output voltage and feeds the output voltage to a load; and
a current driver block which generates an output current of the load, wherein
the voltage step-up and -down DC/DC converter comprises:
a first switch of which a first terminal is connected to an application terminal of the input voltage, an N-channel type field effect transistor being used as the first switch;
a first diode of which a cathode is connected to a second terminal of the first switch and of which an anode is connected to a ground terminal;
an inductor of which a first terminal is connected to the second terminal of the first switch;
a second switch of which a first terminal is connected to a second terminal of the inductor and of which a second terminal is connected to the ground terminal;
a second diode of which an anode is connected to the second terminal of the inductor and of which a cathode is connected to a first terminal of the load; and
a boot strap circuit which is connected to the cathode of the first diode.
16. The load driver according to claim 15 , wherein the current driver block comprises:
a current set portion which generates a reference current; and
a constant-current driver which generates the output current based on the reference current.
17. The load driver according to claim 16 , wherein the current set portion outputs a reference voltage based on the reference current to the constant-current driver, and the constant-current driver generates the output current by repeating voltage/current conversion and current/voltage conversion based on the reference voltage.
18. The load driver according to claim 17 , wherein the constant-current driver comprises a plurality of trimmable resistors for the voltage/current conversion and current/voltage conversion.
19. The load driver according to claim 18 , wherein paired ones of the plurality of resistors are disposed in a staggered layout.
20. The load driver according to claim 16 , wherein the current set portion sets the reference current based on a value of whichever is lower of a control voltage fed in externally and a constant voltage previously determined internally.