SWCS142 July 2018 TPS650861
PRODUCTION DATA.
The PMIC synchronous step-down DCDC converters include a unique hysteretic PWM controller scheme which enables a high switching frequency converter, excellent transient and AC load regulation as well as operation with cost-competitive external components. The device operates on a quasi-fixed frequency and allows filtering of the switch noise by external filter components. The PMIC device offers fixed output voltage options featuring smallest solution size by using only three external components per converter.
A significant advantage of PMIC compared to other hysteretic PWM controller topologies is its excellent AC load transient regulation capability. When the output voltage falls below the threshold of the error comparator, a switch pulse is initiated, and the high-side switch is turned on. The high-side switch remains turned on until a minimum ON-time of tONmin expires and the output voltage trips the threshold of the error comparator or the inductor current reaches the high-side switch current limit. When the high-side switch turns off, the low-side switch rectifier is turned on and the inductor current ramps down until the high-side switch turns on again. In PWM mode operation, negative inductor current is allowed to enable continuous conduction mode even at no load condition.