Current mode hysteretic control with clocked ramp
First Claim
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1. A current mode hysteretic control circuit, in a DC-DC switching converter, comprising:
- a high-side switch, configured to turn off when a current in a coil exceeds a peak current limit.a low-side switch, configured to turn off when the current in the coil falls below a valley current limit;
a ramp generator, configured to generate a current ramp, initiated with a reference clock signal, and reset when said valley current limit or said peak current limit is reached by said coil current, wherein said current ramp is used to lock a frequency of said switching converter; and
said switching converter configured with an offset between said peak current limit and said valley current limit, to provide hysteretic current-mode operation.
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Abstract
Current in a switching converter is controlled using a current-mode hysteretic controller. The high-side switch (usually a PMOS) is turned off when the current in the coil exceeds a certain peak control current. The low-side switch (usually an NMOS) is turned off when the current in the coil falls below a certain valley control current. A current ramp is added to one of these control currents, either peak or valley. The current ramp is initiated by a reference clock signal, which has the effect of synchronizing the switching converter to the reference clock.
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Citations
29 Claims
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1. A current mode hysteretic control circuit, in a DC-DC switching converter, comprising:
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a high-side switch, configured to turn off when a current in a coil exceeds a peak current limit. a low-side switch, configured to turn off when the current in the coil falls below a valley current limit; a ramp generator, configured to generate a current ramp, initiated with a reference clock signal, and reset when said valley current limit or said peak current limit is reached by said coil current, wherein said current ramp is used to lock a frequency of said switching converter; and said switching converter configured with an offset between said peak current limit and said valley current limit, to provide hysteretic current-mode operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for current mode hysteretic control, in a DC-DC switching converter, comprising:
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turning off a high-side device, when a current in a coil exceeds a peak current limit; turning off a low-side device, when the current in the coil falls below a valley current limit; adding a current ramp to one of the current limits; and initiating the current ramp with a reference clock signal, and resetting the current ramp when the coil current reaches the valley current limit, or the peak current limit, synchronizing a switching converter to the reference clock, providing hysteretic current-mode operation. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification