NSC LM2614BTLX, LM2614BTL, LM2614ATL, LM2614ATLX Datasheet

LM2614
400mA Sub-Miniature Adjustable DC-DC Converter
Optimized for RF Power Amplifiers

LM2614 400mA Sub-Miniature Adjustable DC-DC Converter Optimized for RF Power Amplifiers

August 2002

General Description

The LM2614 DC-DC converter is optimized for powering RF
power amplifiers (PAs) from a single Lithium-Ion cell. It steps
down an input voltage of 2.8V to 5.5V to an output of 1.0V to

3.6V at up to 400mA (300mA for B grade). Output voltage is
set using an analog input to VCON in the application circuit.

The device offers three modes for mobile phones and similar
RF PA 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 LM2614 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. Ahigh switching
frequency (600kHz) allows use of tiny surface-mount com­ponents.

The LM2614 can be dynamically controlled for output volt­age changes from 1.0V to 3.6V in
tures external compensation to tailor the response to a wide
range of operating conditions.

<

30µs. The device fea-

Key Specifications

n Operates from a single LiION cell (2.8V to 5.5V)
n Adjustable output voltage (1.0V to 3.6V)

±

n

1% DC feedback voltage precision

n 400mA maximum load capability(300mA for B grade)
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

IN

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 Battery Powered RF Devices

© 2002 National Semiconductor Corporation DS200367 www.national.com

Typical Application Circuits

LM2614

FIGURE 1. Typical Circuit for Powering RF Power Amplifiers

20036701

FIGURE 2. Typical Circuit for 2.5V Output Voltage

FIGURE 3. Typical Circuit for 1.5V Output Voltage

20036702

20036703

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Connection Diagrams

10-Bump micro SMD Package

LM2614

Top View

20036704

Bottom View

20036705

Ordering Information

Order Number Package Type

LM2614ATL

LM2614BTL XYTT S50B 250 Tape and Reel

LM2614ATLX XYTT S50A 3000 Tape and Reel

LM2614BTLX XYTT S50B 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 S50A 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 LM2614.

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

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

LM2614

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

JA

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

V

V

V

IN

FB

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

I

SHDN

I

Q1_PWM

I

Q2_PFM

R

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

R

DSON (N)

Pin-Pin Resistance for
N FET

R

DSON (TC)

FET Resistance
Temperature Coefficient

I

LIM

Switch Peak Current Limit
(Note 6)

V

IH

Logic High Input, EN,
SYNC/MODE

V

IL

Logic Low Input, EN,
SYNC/MODE

F

SYNC

SYNC/MODE Clock
Frequency Range

F

OSC

Internal Oscillator
Frequency

T

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 LM2614 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 LM2614 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

LM2614ATL 510 690 850

LM2614BTL 400 690 980

0.95 1.3 V

0.4 0.80 V

(Note 7)

500 1000 kHz

LM2614ATL, PWM Mode 468 600 732

LM2614BTL, PWM Mode 450 600 750

200 ns

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

IN

±

2kV

mA

kHz

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Typical Performance Characteristics

LM2614ATL, Circuit of Figure 4,VIN= 3.6V, TA= 25˚C, unless otherwise noted.

Shutdown Quiescent Current vs Temperature

Quiescent Supply Current vs Supply Voltage

LM2614

(Circuit in Figure 3)

Output Voltage vs Supply Voltage

= 1.0V, PWM MODE)

(V

OUT

Output Voltage vs Output Current

= 1.0V, PWM MODE)

(V

OUT

20036708

20036722

Output Voltage vs Supply Voltage

(V

= 1.5V, PWM MODE)

OUT

20036724 20036709

Output Voltage vs Output Current

(V

= 1.5V, PWM MODE)

OUT

20036710

20036711

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