(

)

L

DS(ON)

O

O

I

R

(max)

R

(max)

I

(max)

V

(min)

V

+

´

+

=

TPS62050, TPS62051, TPS62052, TPS62054, TPS62056

www.ti.com

SLVS432F – SEPTEMBER 2002 – REVISED JUNE 2015

Device Functional Modes (continued)

It is possible to switch from forced PWM mode to the power-save mode during operation by pulling the SYNC pin

low. The flexible configuration of the SYNC pin during operation of the device allows efficient power management

by adjusting the operation of the TPS6205x devices to the specific system requirements.

9.4.3 Power-Save Mode Operation (SYNC = LOW)

As the load current decreases, the converter enters the power-save mode operation. During power-save mode

the converter operates with reduced switching frequency in PFM and with a minimum quiescent current to

maintain high-efficiency. Whenever the average output current goes below the skip threshold, the converter

enters the power-save mode. The average current depends on the input voltage. The current is 100 mA at low

input voltages and up to 200 mA with maximum input voltage. The average output current must be less than the

voltage is monitored with a comparator. When the output voltage falls below the comparator low threshold set to

current of typically 200 mA is reached. The N-channel rectifier turns on and the inductor current ramps down. As

the inductor current approaches zero, the N-channel rectifier is turned off and the switch is turned on starting the

next pulse. When the output voltage can not be reached with a single pulse, the device continues to switch with

its normal operating frequency, until the comparator detects the output voltage to be 1.6% above the nominal

output voltage. The converter wakes up again when the output voltage falls below the comparator low threshold.

This control method reduces the quiescent current to typically to 12 µA and the switching frequency to a

minimum achieving the highest converter efficiency. Having these skip current thresholds 0.8% and 1.6% above

the nominal output voltage gives a lower absolute voltage drop during a load transient as anticipated with a

standard converter operating in this mode.

9.4.4 100% Duty Cycle Low Dropout Operation

The TPS6205x devices offer the lowest possible input to output voltage difference while still maintaining

operation with the use of the 100% duty cycle mode. In this mode, the P-channel switch is constantly turned on.

This is particularly useful in battery-powered applications to achieve longest operation time by taking full

advantage of the whole battery voltage range. The minimum input voltage to maintain regulation depends on the

load current and output voltage and can be calculated using Equation 1.

(1)

9.4.5 No Load Operation

If the converter operates in the forced PWM mode and there is no load connected to the output, the converter

regulates the output voltage by allowing the inductor current to reverse for a short period of time.

Copyright © 2002–2015, Texas Instruments Incorporated

Submit Documentation Feedback

11

Product Folder Links: TPS62050 TPS62051 TPS62052 TPS62054 TPS62056