NSC LM2619ATLX, LM2619ATL Datasheet

November 2002

LM2619 500mA Sub-Miniature Step-Down DC-DC Converter

General Description

The LM2619 step down DC-DC converter is optimized for powering circuits from a single Lithium-Ion cell. It steps down an input voltage of 2.8V to 5.5V to an output of 1.5V to 3.6V at up to 500mA. Output voltage is set using resistor feedback dividers.

The device offers three modes for mobile phones and similar portable applications. Fixed-frequency PWM mode minimizes RF interference. A SYNC input allows synchronizing the switching frequency in a range of 500kHz to 1MHz. Low current hysteretic PFM mode reduces quiescent current to 160µA (typ.). Shutdown mode turns the device off and reduces battery consumption to 0.02µA (typ.).

Current limit and thermal shutdown features protect the device and system during fault conditions.

The LM2619 is available in a 10 bump micro SMD package. This packaging uses National’s chip-scale micro SMD technology and offers the smallest possible size. A high switching frequency (600kHz) allows use of tiny surface-mount components.

The device features external compensation to tailor the response to a wide range of operating conditions.

Key Specifications

n Operates from a single LiION cell (2.8V to 5.5V) n Output voltage (1.5V to 3.6V)

1% DC feedback voltage precision

n 500mA maximum load capability n 600µA typ PWM mode quiescent current n 0.02µA typ shutdown current n 600kHz PWM switching frequency n SYNC input for PWM mode frequency synchronization

from 500kHz to 1MHz

n High efficiency (96% typ at 3.9V

in PWM mode from internal synchronous rectification

n 100% Maximum Duty Cycle for Lowest Dropout

, 3.6V

and 200mA)

OUT

Features

n Sub-miniature 10-bump thin micro SMD package n Uses small ceramic capacitors n 5mV typ PWM mode output voltage ripple(C n Internal soft start n Current overload protection n Thermal Shutdown n External compensation

OUT

= 22µF)

Applications

n Mobile Phones n Hand-Held Radios n RF PC Cards n Wireless LAN Cards

Typical Application Circuits

LM2619

20057401

FIGURE 1. Typical Circuit for 1.8V Output Voltage

FIGURE 2. Typical Circuit for 2.5V Output Voltage

FIGURE 3. Typical Circuit for 1.5V Output Voltage

20057402

20057403

www.national.com 2

Connection Diagrams

10-Bump micro SMD Package

LM2619

Top View

20057404

Bottom View

20057405

Ordering Information

Order Number Package Type

LM2619ATL

LM2619ATLX XYTT S76A 3000 Tape and Reel

(*) XY - denotes the date code marking (2 digit) in production (*) TT - refers to die run/lot traceability for production (*) S - product line designator Package markings may change over the course of production.

10-bump Wafer Level Chip Scale

(micro SMD)

NSC Package

Marking (

XYTT S76A 250 Tape and Reel

)

Supplied As

Pin Description

Pin Number Pin Name Function

A1 FB Feedback Analog Input.

B1 EANEG Inverting input of error amplifier.

C1 EAOUT Output of error amplifier.

D1 SYNC/MODE Synchronization Input. Use this digital input for frequency selection or modulation control.

Set: SYNC/MODE = high for low-noise 600kHz PWM mode SYNC/MODE = low for low-current PFM mode SYNC/MODE = a 500kHz– 1MHz external clock for synchronization in PWM mode. (See Synchronization and Operating Modes in the Device Information section.)

D2 EN Enable Input. Set this Schmitt trigger digital input high for normal operation. For shutdown,

set low. Set EN low during system power-up and other low supply voltage conditions. (See Shutdown Mode in the Device Information section.)

D3 PGND Power Ground.

C3 SW Switching Node connection to the internal PFET switch and NFET synchronous rectifier.

Connect to an inductor with a saturation current rating that exceeds the max Switch Peak Current Limit of the LM2619.

B3 PVIN Power Supply Voltage Input to the internal PFET switch. Connect to the input filter

capacitor.

A3 VDD Analog Supply Input. If board layout is not optimum, an optional 0.1µF ceramic capacitor

is suggested.

A2 SGND Analog and Control Ground.

www.national.com3

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

LM2619

please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

PVIN, VDD to SGND −0.2V to +6V

PGND to SGND, PVIN to VDD −0.2V to +0.2V

EN, EAOUT, EANEG, SYNC/MODE

Storage Temperature Range −45˚C to +150˚C

Lead Temperature (Soldering, 10 sec.) 260˚C

Junction Temperature (Note 2) −25˚C to +125˚C

Minimum ESD Rating

(Human Body Model, C = 100 pF, R = 1.5 kΩ)

Thermal Resistance (θ

) (Note 3) 140˚C/W

to SGND −0.2V to +6V

FB, SW (GND −0.2V) to

(VDD +0.2V)

Electrical Characteristics

Specifications with standard typeface are for TA=TJ= 25˚C, and those in boldface type apply over the full Operating Temperature Range of T

Symbol Parameter Conditions Min Typ Max Units

HYST

Input Voltage Range PVIN = VDD = VIN(Note 4) 2.8 3.6 5.5 V

Feedback Voltage 1.485 1.50 1.515 V

PFM Comparator Hysteresis Voltage

SHDN

Q1_PWM

Q2_PFM

DSON (P)

Shutdown Supply Current VIN = 3.6V, EN = 0V 0.02 3 µA

DC Bias Current into VDD SYNC/MODE = VIN

Pin-Pin Resistance for P FET

DSON (N)

Pin-Pin Resistance for N FET

DSON (TC)

FET Resistance Temperature Coefficient

LIM

Switch Peak Current Limit (Note 6)

Logic High Input, EN, SYNC/MODE

Logic Low Input, EN, SYNC/MODE

SYNC

SYNC/MODE Clock Frequency Range

OSC

Internal Oscillator Frequency

min

Minimum ON-Time of PFET Switch in PWM Mode

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but device specifications may not be guaranteed. For guaranteed specifications and associated test conditions, see the Min and Max limits and Conditions in the Electrical Characteristics table. Typical (typ) specifications are mean or average values at 25˚C and are not guaranteed.

Note 2: Thermal shutdown will occur if the junction temperature exceeds 150˚C.

Note 3: Thermal resistance specified with 2 layer PCB (0.5/0.5 oz. cu).

Note 4: The LM2619 is designed for mobile phone applications where turn-on after system power-up is controlled by the system controller. Thus, it should be kept

in shutdown by holding the EN pin low until the input voltage exceeds 2.8V.

Note 5: The hysteresis voltage is the minimum voltage swing on the FB pin that causes the internal feedback and control circuitry to turn the internal PFET switch on and then off during PFM mode. When resistor dividers are used like in the operating circuit of Figure 4, the hysteresis at the output will be the value of the hysteresis at the feedback pin times the resistor divider ratio. In this case, 24mV (typ) x ((46.4k + 33.2k)/33.2k).

Note 6: Current limit is built-in, fixed, and not adjustable. If the current limit is reached while the voltage at the FB pin is pulled below 0.7V, the internal PFET switch turns off for 2.5µs to allow the inductor current to diminish.

Note 7: SYNC driven with an external clock switching between V the external clock frequency. The LM2619 synchronizes to the rising edge of the external clock.

= −25˚C to +85˚C. Unless otherwise specified, PVIN = VDD = EN = SYNC/MODE = 3.6V.

A=TJ

PFM Mode (SYNC/MODE = 0V) (Note 5)

FB=2V

SYNC/MODE = 0V FB=2V

24 mV

600 725 µA

160 195 µA

395 550 mΩ

330 500 mΩ

0.5 %/C

620 810 1000 mA

0.95 1.3 V

0.4 0.80 V

(Note 7)

PWM Mode

500 1000 kHz

468 600 732 kHz

200 ns

and GND. When an external clock is present at SYNC; the IC is forced to be in PWM mode at

2kV

www.national.com 4

LM2619

Typical Performance Characteristics LM2619ATL, Circuit of Figure 3,V

less otherwise noted.

Shutdown Quiescent Current vs Temperature

Quiescent Supply Current vs Supply Voltage

20057408

Output Voltage vs Supply Voltage

= 1.5V, PWM MODE)

OUT

(Circuit in Figure 3)

Output Voltage vs Supply Voltage

= 1.5V, PFM MODE)

OUT

= 3.6V, TA= 25˚C, un-

20057422

Output Voltage vs Output Current

= 1.5V, PWM MODE)

OUT

20057409

20057411

Output Voltage vs Output Current

= 1.5V, PFM MODE)

OUT

20057410

20057413

www.national.com5

+ 10 hidden pages