US 12,438,462 B2
Switching converter and oscillator thereof
Fei Xiao, Beijing (CN); and Xiang Yu, Beijing (CN)
Assigned to SG MICRO CORP, Beijing (CN)
Appl. No. 18/260,092
Filed by SG MICRO CORP, Beijing (CN)
PCT Filed Oct. 21, 2021, PCT No. PCT/CN2021/125336
§ 371(c)(1), (2) Date Jun. 30, 2023,
PCT Pub. No. WO2022/142625, PCT Pub. Date Jul. 7, 2022.
Claims priority of application No. 202011601971.3 (CN), filed on Dec. 30, 2020.
Prior Publication US 2024/0055988 A1, Feb. 15, 2024
Int. Cl. H02M 3/158 (2006.01)
CPC H02M 3/158 (2013.01) 15 Claims
OG exemplary drawing
 
1. An oscillator of a switching converter, wherein the oscillator comprises:
a charging current generating circuit, configured to generate a charging current;
a clock signal generator circuit, configured to generate a slope voltage according to the charging current, compare the slope voltage with a first reference voltage to obtain a comparison result, and generate a clock signal according to the comparison result,
wherein, the charging current generating circuit comprises a variable resistor and a current limiting module, which is configured to limit a current value of the charging current to a preset current value when the variable resistor is shorted or opened,
wherein the charging current generating circuit further comprises:
a first transistor and a second transistor being connected in series between a power supply voltage and the variable resistor;
a fourth transistor being connected between the power supply voltage and the clock signal generator circuit, wherein the fourth transistor and the first transistor form a current mirror, and a second terminal of the fourth transistor is used for supplying the charging current; and
an operational amplifier, which has a non-inverting input terminal being used for receiving a second reference voltage, an inverting input terminal being connected to a first node with a first terminal of the variable resistor, and an output terminal being connected to a control terminal of the second transistor,
wherein, the operational amplifier is configured to provide a feedback adjustment signal to the second transistor according to a node voltage of the first node and the second reference voltage, to adjust the current value of the charging current,
wherein the current limiting module comprises:
a first current source, having a first terminal being connected to the power supply voltage and having a second terminal being connected to the first node.