TPS65251-2RHAR

The TPS65251-x features three wide-input-range synchronous high-efficiency buck converters. These converters are designed to simplify their application while allowing designers to optimize their usage for the target application. The converters operate in 5V, 9V, 12V, or 15V systems and integrate power transistors. An external resistor divider can be used to set the output voltage to any value between 0.8V and the input supply voltage. Each converter features the following pins: an enable pin for delayed startup to support sequencing; a soft-start pin for adjustable soft-start time via selection of a soft-start capacitor; and a current limit (RLIMx) pin that allows designers to adjust the current limit and optimize inductor selection by choosing an external resistor. The converters use current-mode control to simplify RC compensation. The switching frequency can be set either by selecting an external resistor connected to the ROSC pin or synchronized to an external clock connected to the SYNC pin. The switching regulators are designed to operate in the frequency range of 300kHz to 2.2MHz. Buck 1 operates 180° out of phase with Bucks 2 and 3 (Bucks 2 and 3 operate in phase), minimizing input filter requirements. The TPS65251-x features monitoring circuitry to monitor each converter output. Upon completion of sequencing, the PGOOD pin is asserted and reports all PG signals after an optional power-on reset delay. The PGOOD signal is active-high. All converters feature an automatic low-power pulse PFM skip mode, which improves efficiency during light-load and standby operation while maintaining an extremely low output ripple, achieving a value below 2% at low output voltages.

Applications

• Set-top box
• Blu-ray DVD
• DVR
• Digital TV (DTV)
• Automotive audio/video
• Security camera

Key features

• Wide input supply voltage range (4.5V to 18V)
• Output range: 0.8V to VIN – 1V
• Continuous load current: 3A (Buck Switch 1), 2A (Buck Switch 2 and 3)
• Maximum current: 3.5A (Buck Switch 1), 2.5A (Buck Switch 2 and 3)
• Adjustable switching frequency: 300kHz to 2.2MHz (set by external resistor)
• Dedicated enable pin per buck channel
• External synchronization pin for oscillator
• Adjustable current limit set by external resistor
• Soft-start pin
• Current mode control with simple compensation network
• Power good indication
• Auto PFM/PWM operation
• VQFN package, 40-pin 6mm × 6mm RHA