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Power-Save Mode

Device Enable

Under-Voltage Lockout

Autodischarge

Low-Battery Detector Circuit (LBI and LBO)

Antiringing Switch

TPS61010, TPS61011

TPS61012, TPS61013

TPS61014, TPS61015, TPS61016

SLVS314D – SEPTEMBER 2000 – REVISED JUNE 2005

DETAILED DESCRIPTION (continued)

The TPS61010 is designed for high efficiency over a wide output current range. Even at light loads, the efficiency

stays high because the switching losses of the converter are minimized by effectively reducing the switching

frequency. The controller enters a powersave-mode if certain conditions are met. In this mode, the controller only

switches on the transistor if the output voltage trips below a set threshold voltage. It ramps up the output voltage

with one or several pulses, and goes again into powersave-mode once the output voltage exceeds a set

threshold voltage.

The device is shut down when EN is set to GND. In this mode, the regulator stops switching, all internal control

circuitry including the low-battery comparator, is switched off, and the load is disconnected from the input (as

described above in the synchronous rectifier section). This also means that the output voltage may drop below

the input voltage during shutdown.

The device is put into operation when EN is set high. During start-up of the converter, the duty cycle is limited in

order to avoid high peak currents drawn from the battery. The limit is set internally by the current limit circuit and

is proportional to the voltage on the COMP-pin.

An under-voltage lockout function prevents the device from starting up if the supply voltage on VBAT is lower

than approximately 0.7 V. This under-voltage lockout function is implemented in order to prevent the

malfunctioning of the converter. When in operation and the battery is being discharged, the device will

automatically enter the shutdown mode if the voltage on VBAT drops below approximately 0.7 V.

The autodischarge function is useful for applications where the supply voltage of a

µC, µP, or memory has to be

removed during shutdown in order to ensure a defined state of the system.

The autodischarge function is enabled when the ADEN is set high, and is disabled when the ADEN is set to

GND. When the autodischarge function is enabled, the output capacitor will be discharged after the device is

shut down by setting EN to GND. The capacitors connected to the output are discharged by an integrated switch

of 300

Ω, hence the discharge time depends on the total output capacitance. The residual voltage on VOUT is

less than 0.4 V after autodischarge.

The low-battery detector circuit is typically used to supervise the battery voltage and to generate an error flag

when the battery voltage drops below a user-set threshold voltage. The function is active only when the device is

enabled. When the device is disabled, the LBO-pin is high impedance. The LBO-pin goes active low when the

voltage on the LBI-pin decreases below the set threshold voltage of 500 mV

±15 mV, which is equal to the

internal reference voltage. The battery voltage, at which the detection circuit switches, can be programmed with a

resistive divider connected to the LBI-pin. The resistive divider scales down the battery voltage to a voltage level

of 500 mV, which is then compared to the LBI threshold voltage. The LBI-pin has a built-in hysteresis of 10 mV.

See the application section for more details about the programming of the LBI-threshold.

If the low-battery detection circuit is not used, the LBI-pin should be connected to GND (or to VBAT) and the

LBO-pin can be left unconnected. Do not let the LBI-pin float.

The device integrates a circuit that removes the ringing that typically appears on the SW-node when the

converter enters the discontinuous current mode. In this case, the current through the inductor ramps to zero and

the integrated PMOS switch turns off to prevent a reverse current from the output capacitors back to the battery.

Due to remaining energy that is stored in parasitic components of the semiconductors and the inductor, a ringing

dampens this ringing.

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