SW

OUT

L

L

IT

VALLEY,LIM

PEAK,LIMIT

f

D)

(

L

V

I

I

I

I

-

´

=

+

=

1

Inductor

Current

t

Valley current limit

Maximum load current

Peak current limit

Secondary current limit

TLV62565

TLV62566

www.ti.com

SLVSBC1 – OCTOBER 2013

ENABLING/DISABLING THE DEVICE

The device is enabled by setting the EN input to a logic HIGH. Accordingly, a logic LOW disables the device. If

the device is enabled, the internal power stage starts switching and regulates the output voltage to the set point

voltage. The EN input must be terminated and should not be left floating.

SOFT START

After enabling the device, internal soft-start circuitry monotonically ramps up the output voltage which reaches

nominal output voltage during a soft-start time of 250 µs (typical). This avoids excessive inrush current and

creates a smooth output voltage rise slope. It also prevents excessive voltage drops of primary cells and

rechargeable batteries with high internal impedance.

If the output voltage is not reached within the soft-start time, such as in the case of a heavy load, the converter

enters regular operation. The TLV62565/6 are able to start into a pre-biased output capacitor. The converter

starts with the applied bias voltage and ramps the output voltage to its nominal value.

SWITCH CURRENT LIMIT

The switch current limit prevents the device from high inductor current and drawing excessive current from a

battery or input voltage rail. Excessive current might occur with a heavy load or shorted output circuit condition.

The TLV62565/6 adopt valley current control by sensing the current of the low-side MOSFET. Once the low-side

valley switch current limit is tripped, the low-side MOSFET is turned off and limits the inductor's valley current.

The high-side current is also limited which is determined by the on time of the high-side MOSFET and inductor

limit is approximately 1.97 A with a typical valley current limit of 1.7 A.

Additionally, there is a secondary high-side current limit (typical 2 A) to prevent the current from going too high,

which is shown in Figure 24. Due to the internal propagation delay, the real current limit value might be higher

than the static current limit in the electrical characteristics table.

Figure 24. Switch Current Limit

where:

•

•

(1)

POWER GOOD

The TLV62566 integrates a Power Good output going low when the output voltage is below its nominal value.

The Power Good output stays high impedance once the output is above 95% of the regulated voltage and is low

once the output voltage falls below typically 90% of the regulated voltage. The PG pin is an open drain output

and is specified to sink typically up to 0.5 mA. The Power Good output requires a pull-up resistor connected to

any voltage lower than 5.5 V. When the device is off due to UVLO or thermal shutdown, the PG pin is pulled to

logic low.

Copyright © 2013, Texas Instruments Incorporated

Submit Documentation Feedback

11

Product Folder Links: TLV62565 TLV62566