Datasheet

TPS82690

TPS82695

TPS82697

SLVSA66B –JUNE 2011–REVISED FEBRUARY 2012

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MODE SELECTION

The MODE pin allows to select the operating mode of the device. Connecting this pin to GND enables the

automatic PWM and power-save mode operation. The converter operates in regulated frequency PWM mode at

moderate to heavy loads and in the PFM mode during light loads, which maintains high efficiency over a wide

load current range.

Pulling the MODE pin high forces the converter to operate in the PWM mode even at light load currents. The

advantage is that the converter operates with a fixed frequency that allows simple filtering of the switching

frequency for noise-sensitive applications. In this mode, the efficiency is lower compared to the power-save

mode during light loads.

For additional flexibility, it is possible to switch from power-save mode to PWM mode during operation. This

allows efficient power management by adjusting the operation of the converter to the specific system

requirements.

LOW DROPOUT, 100% DUTY CYCLE OPERATION

The device starts to enter 100% duty cycle mode once input and output voltage come close together. In order to

maintain the output voltage, the DC/DC converter's high-side MOSFET is turned on 100% for one or more

cycles.

With further decreasing V

the high-side switch is constantly turned on, thereby providing a low input-to-output

voltage difference. This is particularly useful in battery-powered applications to achieve longest operation time by

taking full advantage of the whole battery voltage range.

SOFT START

The TPS8269xSIP has an internal soft-start circuit that limits the inrush current during start-up. This limits input

voltage drops when a battery or a high-impedance power source is connected to the input of the MicroSiP™

converter.

The soft-start system progressively increases the switching on-time from a minimum pulse-width of 35ns as a

function of the output voltage. This mode of operation continues for c.a. 100μs after enable. Should the output

voltage not have reached its target value by that time, such as in the case of heavy load, the soft-start transitions

to a second mode of operation.

If the output voltage has raised above 0.5V (approximately), the converter increases the input current limit

thereby enabling the power supply to come-up properly. The start-up time mainly depends on the capacitance

present at the output node and load current.

ENABLE

The TPS8269xSIP device starts operation when EN is set high and starts up with the soft start as previously

described. For proper operation, the EN pin must be terminated and must not be left floating.

Pulling the EN pin low forces the device into shutdown. In this mode, all internal circuits are turned off and V

current reduces to the device leakage current, typically a few hundred nanoamps.

The TPS8269xSIP device can actively discharge the output capacitor when it turns off (refer to Ordering

Information Table). The integrated discharge resistor has a typical resistance of 100 Ω. The required time to

ramp-down the output voltage depends on the load current and the capacitance present at the output node.

Product Folder Link(s): TPS82690 TPS82695 TPS82697