NSC LM2618BTL, LM2618ATL, LM2618BTLX Datasheet
September 2002
LM2618
400mA Sub-miniature, High Efficiency, Synchronous
PWM & PFM Programmable DC-DC Converter
LM2618 400mA Sub-miniature, High Efficiency, Synchronous PWM & PFM Programmable DC-DC
Converter
General Description
The LM2618 step-down DC-DC converter is optimized for
powering low voltage circuits from a single Lithium-Ion cell. It
provides up to 400mA (300mA for B grade), over an input
voltage range of 2.8V to 5.5V. Pin programmable output
voltages of 1.80V, 1.83V, 1.87V or 1.92V allow adjustment
for MPU voltage options without board redesign or external
feedback resistors. Internal synchronous rectification provides high efficiency in both PWM and PFM operation.
The device has three pin-selectable modes for maximizing
battery life in mobile phones and similar portable applications. Low-noise PWM mode offers 600kHz fixed-frequency
operation to reduce interference in RF and data acquisition
applications during full-power operation. A SYNC input allows synchronizing the switching frequency in a range of
500kHz to 1MHz to avoid noise from intermodulation with
system frequencies. Low-current hysteretic PFM mode reduces quiescent current to 180 µA (typ.) during system
standby. Shutdown mode turns the device off and reduces
battery consumption to 0.02µA (typ.). Additional features
include soft start and current overload protection.
The LM2618 is available in a 10 pin micro SMD packge. This
package uses National’s wafer level chip-scale micro SMD
technology and offers the smallest possible size. Only three
small external surface-mount components, an inductor and
two ceramic capacitors are required.
Key Specifications
n Operates from a single LiION cell (2.8V to 5.5V)
n Internal synchronous rectification provides high
efficiency in both PWM and PFM
n Pin programmable output voltage (1.80V, 1.83V, 1.87V
and 1.92V)
n 400mA maximum load capability (300mA for B grade)
±
n
2% PWM mode DC output voltage precision
n 5mV typ PWM mode output voltage ripple
n 180 µA typ PFM mode quiescent current
n 0.02µA typ shutdown mode current
n Internal synchronous rectification for high efficiency
(91% at 3.0V
n 600kHz PWM mode switching frequency
n SYNC input for PWM mode frequency synchronization
from 500kHz to 1MHz
, 1.92V
IN
OUT
)
Features
n Sub-miniature 10-pin micro SMD package
n Only three tiny surface-mount external components
required
n Uses small ceramic capacitors.
n Internal soft start
n Current overload protection
n Thermal Shutdown Protection
n No external compensation required
Applications
n Mobile Phones
n Hand-Held Radios
n Battery Powered Devices
Typical Application Circuit
20036402
© 2002 National Semiconductor Corporation DS200364 www.national.com
Connection Diagrams
micro SMD package
LM2618
TOP VIEW
20036404
BOTTOM VIEW
Ordering Information
Order Number Package Type NSC Package
Marking(*)
10-Pin micro SMD
LM2618ATL
LM2618BTL XYTT IS55B 250 Units, Tape and Reel
LM2618ATLX XYTT IS55A 3000 Units, Tape and Reel
10-bump Wafer Level Chip Scale
(micro SMD)
XYTT IS55A 250 Units, Tape and Reel
LM2618BTLX XYTT IS55B 3000 Units, Tape and Reel
(*) XY - denotes the date code marking (2 digit) in production
(*) TT - refers to die run/lot traceability for production
(*) I - pin one indication
(*) S - Product line designator
Note that Package Marking may change over the course of production
Supplied As
20036405
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Pin Description
Pin Number (*) Pin Name Function
A1 FB Feedback Analog Input. Connect to the output at the output filter capacitor (Figure 1)
B1 VID1 Output Voltage Control Inputs. Set the output voltage using these digital inputs (see Table
C1 VID0
D1 SYNC/MODE Synchronization Input. Use this digital input for frequency selection or modulation control.
D2 EN Enable Input. For shutdown, set low to SGND. (See Shut down Mode in the Device
D3 PGND Power Ground
C3 SW Switching Node connection to the internal PFET switch and NFET synchronous rectifier.
B3 PVIN Power Supply 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
A2 SGND Analog and Control Ground
(*) Note that the pin numbering scheme for the microSMD package was revised in April,2002 to conform to JEDEC standard. Only the pin numbers were revised.
No changes to the physical location of the inputs/outputs were made. For reference purpose, the obsolete numbering had FB as pin 1, VID1 as pin 2, VID0 as pin
3, SYNC as pin 4, EN as pin 5, PGND as pin 6, SW as pin 7, PVIN as pin 8, VDD as pin 9 and SGND as pin 10.
1). The output defaults to 1.87V if these pins are unconnected.
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 to an external clock
in PWM mode. See Synchronization and Operating Modes in the Device Information
section.
Information section.)
Connect to an inductor with a saturation current rating that exceeds the max Switch Peak
Current Limit specification of the LM2618 (Figure 1)
(Figure 1).
is suggested (Figure 1)
LM2618
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
LM2618
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
PVIN, VDD, to SGND −0.2V to +6V
PGND to SGND −0.2V to +0.2V
EN, SYNC/MODE, VID0, VID1 to
SGND −0.2V to +6V
Lead temperature
(Soldering, 10 sec.) 260˚C
Junction Temperature (Note 2) −25˚C to 125˚C
Minimum ESD Rating
Human body model, C = 100pF, R =
1.5 kΩ
Thermal Resistance (θ
)
JA
LM2618ATL & LM2618BTL (Note 3) 140˚C/W
FB, SW (GND −0.2V) to
(VDD +0.2V)
Storage Temperature Range −45˚C to +150˚C
Electrical Characteristics
Specifications with standard typeface are for TA=TJ= 25˚C, and those in bold face type apply over the full Operating Temperature Range (T
0V.
Symbol Parameter Conditions Min Typ Max Units
V
V
V
IN
FB
HYST
Input Voltage Range (Note4)PVIN = VDD = VID1 = VID0 =
Feedback Voltage
(Note 5)
PFM Comparator Hysteresis
Voltage
(Note 6)
I
SHDN
I
Q1
I
Q2
R
DSON (P)
Shutdown Supply Current EN = 0V 0.02 3 µA
DC Bias Current into VDD PFM mode, VFB= 2V 180 215
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 7)
V
EN_H
EN Positive Going
Threshold Voltage
V
EN_L
EN Negative Going
Threshold Voltage
V
SYNC_H
SYNC/MODE Positive
Going Threshold Voltage
V
SYNC_L
SYNC/MODE Negative
Going Threshold Voltage
V
ID_H
V
ID0,VID1
Threshold Voltage
V
ID_L
V
ID0,VID1
Threshold Voltage
I
VID
VID1, VID0 Pull Down
Current
= - 25˚C to +85˚C). Unless otherwise specified, PVIN = VDD = EN = SYNC = 3.6V, VID0 = VID1 =
A=TJ
V
IN
PVIN = VDD = VD1 = V
,
IN
2.8 5.5
3.0 5.5
VID0 = 0V
VID0 = V
VID0 = V
, VID1 = V
IN
, VID1 = 0V 1.793 1.83 1.867
IN
IN
1.764 1.80 1.836
VID0 = 0V, VID1 = 0V 1.833 1.87 1.907
VID0 = 0V, VID1 = V
IN
1.882 1.92 1.958
PFM Mode (SYNC = 0V)
25 mV
PWM mode, VFB= 2V 605 735
LM2618ATL & LM2618BTL
LM2618ATL & LM2618BTL
395 550 mΩ
330 500 mΩ
0.5 %/C
LM2618ATL 540 720 880
LM2618BTL 430 720 1020
VDD = 3.6V
VDD = 3.6V
0.4 0.80 V
0.95 1.3 V
0.95 1.3 V
0.4 0.84 V
Positive Going
Negative Going
0.4 0.83 V
VID1, VID0 = 3.6V
0.92 1.3 V
1.8 3.0 µA
±
2.0kV
V
V
µA
mA
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Electrical Characteristics (Continued)
Specifications with standard typeface are for TA=TJ= 25˚C, and those in bold face type apply over the full Operating Temperature Range (T
0V.
Symbol Parameter Conditions Min Typ Max Units
F
SYNC
SYNC/MODE Clock
Frequency Range
(Note 8)
F
OSC
Internal Oscillator
Frequency
T
min
Minimum ON-Time of P FET
Switch in PWM Mode
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended
to be functional, but parameter 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. Electrical Characteristics table limits are guaranteed by production testing, design or correlation using standard
Statistical Quality Control methods. Typical (Typ) specifications are mean or average values from characterization at 25˚C and are not guaranteed.
Note 2: In PWM mode, Thermal shutdown will occur if the junction temperature exceeds the 150˚C maximum junction temperature of the device.
Note 3: Thermal resistance specified with 2 layer PCB(0.5/0.5 oz. cu).
Note 4: The LM2618 is designed for cell phone applications where turn-on after power-up is controlled by the system processor and internal UVLO (Under Voltage
LockOut) circuitry is unecessary. The LM2618 has no UVLO circuitry and should be kept in shutdown by holding the EN pin low until the input voltage exceeds 2.8V.
Although the LM2618 exhibits safe behavior while enabled at low input voltages, this is not guaranteed.
Note 5: The feedback voltage is trimmed at the 1.87V output setting. The other output voltages result from the pin selection of the internal DAC’s divider ratios. The
precision for the feedback voltages is
Note 6: : The hysteresis voltage is the minimum voltage swing on FB that causes the internal feedback and control circuitry to turn the internal PFET switch on and
then off during PFM mode.
Note 7: Current limit is built-in, fixed, and not adjustable. If the current limit is reached while the output is pulled below about 0.7V, the internal PFET switch turns
off for 2.5 µs to allow the inductor current to diminish.
Note 8: SYNC driven with an external clock switching between VDD and GND. When an external clock is present at SYNC, the IC is forced to PWM mode at the
external clock frequency. The LM2618 synchronizes to the rising edge of the external clock.
= - 25˚C to +85˚C). Unless otherwise specified, PVIN = VDD = EN = SYNC = 3.6V, VID0 = VID1 =
A=TJ
500 1000 kHz
LM2618ATL, PWM Mode
(SYNC = VIN)
LM2618BTL, PWM Mode
(SYNC = VIN)
468 600 732
450 600 750
200 ns
±
2%.
LM2618
kHz
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