US 12,231,028 B2
Pulse frequency modulator for switched mode power supply
Tawen Mei, Sunnyvale, CA (US)
Assigned to TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US)
Filed by TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US)
Filed on Feb. 28, 2022, as Appl. No. 17/682,764.
Prior Publication US 2023/0275573 A1, Aug. 31, 2023
Int. Cl. H02M 3/156 (2006.01); H02M 1/00 (2006.01); H03K 4/00 (2006.01)
CPC H02M 1/0025 (2021.05) [H02M 1/0032 (2021.05); H02M 1/0041 (2021.05); H02M 3/156 (2013.01); H03K 4/00 (2013.01)] 19 Claims
OG exemplary drawing
 
1. An apparatus comprising:
an amplifier having an amplifier output and first and second amplifier inputs, the first amplifier input coupled to a reference voltage terminal, and the second amplifier input coupled to a power input terminal, wherein the first amplifier input is configured to receive a reference voltage, and the second amplifier input is configured to receive a first voltage, the amplifier is configured to generate a first signal representing a first difference between the first voltage and the reference voltage;
a switching frequency modulation circuit including:
a ramp generation circuit having a reset input and a ramp output, wherein the ramp generation circuit is configured to:
generate a ramp signal that starts ramping during a first switching cycle; and
generate a second signal indicating whether the ramp signal intersects with the first signal;
wherein the switching frequency modulation circuit is configured to generate an end cycle signal in response to the second signal indicating that the ramp signal intersects with the first signal;
a comparator having a comparator output and first and second comparator inputs, the first comparator input coupled to the amplifier output, and the second comparator input coupled to the ramp output;
a buffer having a buffer input and a buffer output, the buffer input coupled to the comparator output; and
a switch coupled to the second comparator input, a control terminal of the switch coupled to the comparator output; and
a switching signal generation circuit, wherein in response to the second amplifier input receiving a second voltage and the amplifier generating a third signal representing a second difference between the second voltage and the reference voltage, and the second difference exceeding a threshold, the switching signal generation circuit configured to set an on-time of a second switching cycle based on a peak current.