unless otherwise noted. (Continued)

Efficiency vs Output Current

(V

(Circuit in Figure 1)

Efficiency vs Output Current

(V

(Circuit in Figure 1)

20065135

20065136

Device Information

The LM2619MTC is a simple, step-down DC-DC converter

optimized for powering circuits in mobile phones, portable

communicators, and similar battery powered RF devices. It

is based on a current-mode buck architecture, with synchro-

nous rectification in PWM mode for high efficiency. It is

designed for a maximum load capability of 500mA in PWM

mode. Maximum load range may vary from this depending

on input voltage, output voltage and the inductor chosen.

The device has all three of the pin-selectable operating

modes required for powering circuits in mobile phones and

other sophisticated portable devices with complex power

management needs. Fixed-frequency PWM operation offers

full output current capability at high efficiency while minimiz-

ing interference with sensitive IF and data acquisition cir-

cuits. During standby operation, hysteretic PFM mode re-

duces quiescent current to 160µA typ. to maximize battery

life. Shutdown mode turns the device off and reduces battery

consumption to 0.02µA (typ).

ciency is typically 93% for a 200mA load with 3.6V output,

4.2V input. The efficiency can be increased for lower output

voltages like 1.5V,1.8V by using a schottky diode like

MBRM120L as shown in Figure 4. PWM mode quiescent

current is 600µA typ. The output voltage can be set from

1.5V to 3.6V by using external feedback resistors.

Additional features include soft-start, current overload pro-

tection, over voltage protection and thermal shutdown pro-

tection.

The LM2619MTC is constructed using a 14-pin TSSOP

package. Use of a high switching frequency (600kHz) re-

duces the size of external components.

CIRCUIT OPERATION

Referring to Figure 4, Figure 5, Figure 6 and Figure 7,

the LM2619MTC operates as follows. During the first part of

each switching cycle, the control block in the LM2619MTC

turns on the internal PFET switch. This allows current to flow

from the input through the inductor to the output filter capaci-

20065106

FIGURE 4. Typical Operating Circuit for 3.6V Output Voltage

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