SLVSDN4 June 2017 TPS82150

PRODUCTION DATA.

- 1 Features
- 2 Applications
- 3 Description
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Detailed Description
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information

- SIL|8

The TPS82150 includes an on-time (t_{ON}) circuitry. This t_{ON}, in steady-state operation in PWM and PSM modes, is estimated as:

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Equation 1.

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In PWM mode, the TPS82150 operates with pulse width modulation in continuous conduction mode (CCM) with a t_{ON} shown in Equation 1 at medium and heavy load currents. A PWM switching frequency of typically 2.0MHz is achieved by this t_{ON} circuitry. The device operates in PWM mode as long as the output current is higher than half the inductor's ripple current estimated by Equation 2.

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Equation 2.

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To maintain high efficiency at light loads, the device enters Power Save Mode seamlessly when the load current decreases. This happens when the load current becomes smaller than half the inductor's ripple current. In PSM, the converter operates with reduced switching frequency and with a minimum quiescent current to maintain high efficiency. PSM is also based on the t_{ON} circuitry. The switching frequency in PSM is estimated as:

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Equation 3.

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In PSM, the output voltage rises slightly above the nominal output voltage in PWM mode. This effect is reduced by increasing the output capacitance. The output voltage accuracy in PSM operation is reflected in the electrical specification table and given for a 22-µF output capacitor.

For very small output voltages, an absolute minimum on-time of about 80ns is kept to limit switching losses. The operating frequency is thereby reduced from its nominal value, which keeps efficiency high. Also the off-time can reach its minimum value at high duty cycles. The output voltage remains regulated in such cases.

When V_{IN} decreases to typically 15% above V_{OUT}, the TPS82150 can't enter Power Save Mode, regardless of the load current. The device maintains output regulation in PWM mode.