Datasheet SP6648 Datasheet (Sipex)

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Page 1

SP6648

Ultra-low Quiescent Current,

High Efficiency Boost Regulator

FEATURES

■ Ultra-low 12µA Quiescent Current

■ 400mA Output Current at 2.6V Input: 3.3V

■ 94% Efficiency from 2 cell to 3.3V

OUT

■ Wide Input Voltage Range: 0.95V to 4.5V

■ 3.3V Fixed or Adjustable Output

■ Integrated Synchronous Rectifier: 0.3Ω

■ 0.3Ω Switch

■ Anti-Ringing Switch Technology

Now Available in Lead Free Packaging

■ Programmable Inductor Peak Current

■ Logic Shutdown Control

■ Under Voltage Lock-Out at 0.61V

■ Programmable Low Battery Detect

■ Single or Dual Cell Alkaline

■ Small 10 pin DFN Package and Industry

Standard 10 pin MSOP

The SP6648 is an ultra-low quiescent current, high efficiency step-up DC-DC converter ideal for single cell, dual cell alkaline and Li-Ion battery applications such as digital still cameras, PDA’s, MP3 players, and other portable devices. The SP6648 combines the high delivery associated with PWM control, and the low quiescent current and excellent light-load efficiency of PFM control. The SP6648 features 12µA quiescent current, synchronous rectification, a 0.3Ω charging switch, anti-ringing inductor switch, programmable low battery detect, under-voltage lockout and programmable inductor peak current. The device can be controlled by a 1nA active LOW shutdown pin.

BATT

LBON

SHDN

LBI

LIM

SP6648

10 Pin DFN

OUT

GND

APPLICATIONS

■ Camera Flash LED Driver

■ Wireless Mouse

■ PDA's

■ Pagers

■ Medical Monitors

■ Handheld Portable Devices

■ MP3 Players

DESCRIPTION

TYPICAL APPLICATION CIRCUIT

10µH

BATT

47µF

1.87K

LBI

LBON

SHDN

SP6648

BATT

LBI

LBON

LIM

SHDN

GND

OUT

GND

1µF

205K

124K

47pF

3.3V

OUT

47µF

500

450

400

350

300

250

Io (mA)

200

150

100

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

Vout=3.3V, Ipk=0.85A

Vout=5.0V, Ipk=0.85A

Vin (V)

Maximum Load Current in Operation

Page 2

ABSOLUTE MAXIMUM RATINGS

LX, Vo, V

SHDN, LBI ........................................................... -0.3V to V

Vo, GND, LX Current ....................................................................... 2A

Reverse V Forward V

Storage Temperature .................................................. -65 °C to 150°C

, LBON, FB to GND pin ................................ -0.3 to 6.0V

BATT

Current .............................................................. 220mA

BATT

Current .............................................................. 500mA

BATT

+1.0V

Operating Temperature ................................................ -40°C to +85°C

ESD Rating ........................................................................ 1.5kV HBM

These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

ELECTRICAL SPECIFICATIONS

BATT =VSHDN

otherwise noted. The otherwise specified.

PARAMETER MIN TYP MAX UNITS ♦ CONDITIONS

Input Voltage Operating Range, V

Output Voltage Range, V

Start-up Input Voltage, V

Under Voltage Lock-out/UVLO 0.5 0.61 0.7 V ♦

Output Voltage, V

Quiescent Current into VO, I

Quiescent Current into V

Shutdown Current into V

Efficiency 84 % V

Inductor Current Limit, IPK = 1600/R

Output Current 200 mA V

Minimum Off-Time Constant K

Maximum On-Time Constant K

Enable Valid to Output Stable 300 500 µsI

NMOS Switch Resistance 0.30 0.6 Ω♦I

PMOS Switch Resistance 0.30 0.6 Ω♦I

FB Set Voltage, V

FB Input Current 1 100 nA ♦ VFB =1.3V

LBI Falling Trip Voltage 0.56 0.61 0.66 V ♦

LBI Hysteresis 25 mV

Low Output Voltage for LBON, V

Leakage current for LBON 1 µA ♦ V

SHDN Input Voltage, Note 1

SHDN Input Current 1 100 nA ♦

LX Pin Leakage 3 µA

Note 1: SHDN must transition faster than 1V/100mS for proper operation.

= 2.6V, VFB=0V, I

LOAD

= 0mA, T

= -40°C to +85°C, V

AMB

= +3.3V, typical values at 27°C unless

OUT

♦ denotes the specifications which apply over full operating temperature range -40°C to +85°C, unless

0.7 4.5 V ♦ After Startup

BATT

OUT

BATT

, I

BATT

O, ISDO

BATT, ISDB

OFF

2.5 5.5 V ♦

0.85 1.1 V ♦ R

LOAD

= 3kΩ

3.12 3.30 3.48 V ♦ Internal Feedback Divider

12 25 µA ♦ V

250 750 nA ♦ V

1 500 nA ♦ V

250 750 nA ♦ V

92 % V

650 800 1000 mA ♦ R

LIM

1300 1600 2000 mA ♦ R

100 mA V

150 mA V 400 mA V

0.5 1.0 1.5 V*µs ♦ K

2.5 4.0 5.5 V*µs ♦ KON ≥ T

OUT

SHDN

BATT

LIM

BATT

OFF

LOAD

NMOS

PMOS

= 3.3V, V

= 0V

= 0V, V

= 1.3V, I = 2.6V, I

= 2kΩ = 1kΩ

= 1.3V, R = 2.6V, R

≤ T

OFF (VOUT

ON (VBATT

= 1mA

= 100mA

1.19 1.25 1.31 V ♦ External feedback

0.4 V ♦ V

0.25 ♦ V

1.0 V ♦ V

0.5 ♦ V

2.0 ♦ V

= 1.3V, I

BATT

= 1.3V, V

BATT

= 1.3V

BATT

= 1.3V

BATT

= 2.6V

BATT

= 2.6V

BATT

= 1.5V, Toggle SHDN

= 1.5V

= 2.6V

BATT

= 100mA, R

OUT

= 200mA, R

OUT

= 4kΩ

LIM

= 4kΩ

LIM

=2kΩ

LIM

=2kΩ

LIM

- V

BATT

LIM =

)

= 1mA

SINK

= 3.3V

LBON

2kΩ 2kΩ

Page 3

PIN DESCRIPTION

PIN NUMBER PIN NAME DESCRIPTION

BATT

2 LBI Low Battery Input. LBI below 0.61V causes the SP6648 pin to pull

3 LBON Low Battery Output Not. Open drain NMOS output that sinks current

LIM

5 SHDN Shutdown Not. Tie this pin high to V

6FBFeedback. Connect this pin to GND for fixed +3.3V operation.

7 GND Ground. Connect to ground plane.

8 PGND Power Ground. The inductor charging current flows out of this pin.

9LXInductor Switching Node. Connect one terminal of the inductor to the

10 V

OUT

Battery Voltage. The startup circuitry is powered by this pin. Battery

Voltage is used to calculate switch off time: t

). When the battery voltage drops below 0.61V the SP6648

BATT

OFF

= K

OFF

goes into an undervoltage lockout mode (UVLO), where the part is shut

down.

LBON pin down to ground. Use a resistor divider to program the low

voltage threshold for a specific battery configuration.

to ground when LBI is below 0.61V.

Current Limit Resistor. By connecting a resistor R

ground the inductor peak current is set by I

for R

is 9kΩ (for 180mA) to 1.KΩ (for 1.6A).

LIM

PEAK

for normal operation. Pull

BATT,

from this pin to

LIM

=1600/R

this pin to ground to disable all circuitry inside the chip. In shutdown

the output voltage will float down to a diode drop below the battery

voltage.

Connect this pin to a resistor voltage divider between V

for adjustable output operation.

positive terminal of the battery. Connect the second terminal of the

inductor to this pin. The inductor charging current flows into LX,

through the internal charging N-channel FET, and out the PGND pin.

Output Voltage. The inductor current flows out of this pin during

switch off-time. It is also used as the internal regulator voltage supply.

Connect this pin to the positive terminal of the output capacitor.

/ (V

OUT

. The range

LIM

and GND

OUT

Page 4

FUNCTIONAL DIAGRAM

SHDN

LIM

LBI

BATT

charge end

switch buffer

IUC

QKILL

1.25V

current reference

BATT

Min

OFF

UVLO

REF

VOLOW

CHARGE

SQn

SP6648

INTERNAL

BATT

SDI

0.61V

n Ref Block

current control

IBIAS

0.61V

SDI

Ipkset

0.61V

NMOS

QKILL

PMOS

current

reference

BATT

undercurrent comparator

INTERNAL SUPPLY

Max Ton

overcurrent comparator

SWITCH GROUND

INTERNAL

GROUND

GND

OUT

LOAD

LBON

THEORY OF OPERATION

Detailed Description

The SP6648 is a step-up DC-DC converter that can start up with input voltages as low as 0.85V (typically) and operates with an input voltage down to 0.61V. Ultra low quiescent current of 12µA provides excellent efficiency, up to 94%. In addition to the main switch, a 0.3Ω internal MOSFET the SP6648 has an internal synchronous rectifier, increasing efficiency and reducing the space of an external diode. An internal inductive-damping switch significantly reduces inductive ringing for low noise high efficiency

Control Scheme

A minimum off-time, current limited pulse frequency modulation (PFM) control scheme combines the high output power and efficiency of a pulse width modulation (PWM) device with the ultra low quiescent current of the traditional PFM. At low to moderate output loads the PFM control provides higher efficiency than traditional PWM converters are capable of delivering. At these loads the switching frequency is determined by a minimum off-time (t and a maximum on-time (tON,

MAX

OFF, MIN

) where:

operation. If the supply voltage drops below

0.61V the SP6648 goes into under voltage lockout, thus opening both internal switches. An externally programmable low battery detector with open drain output provides the ability to flag battery low condition. The inductor peak current is externally programmable to allow for

OFF

≥ K

OFF

/ (V

tON ≤ KON / V

= 1.0Vµs and

OFF

KON = 4.0Vµs.

OUT

BATT

- V

with

BATT

) and

a range of inductor values.

)

Page 5

THEORY OF OPERATION: Continued

At light loads (as shown in plot A in Figure 1) the charge cycle will last the maximum value for tON: For a 1V battery this would be as follows:

= KON / V

= 4.0Vµs / 1V = 4.0µs

BATT

The current built up in the coil during the charge cycle gets fully discharged (discontinuous conduction mode DCM) When the current in the coil has reached zero the synchronous rectifier switch is opened and the voltage across the coil (from V

to LX) is shorted internally to

BATT

eliminate inductive ringing.

With increasing load (as shown in plot B in Figure 1) this inductor damping time becomes shorter, because the output will quickly drop below its regulation point due to heavier load. If the load current increases further the SP6648 enters continuous conduction mode (CCM) where there is always current flowing in the inductor. The charge time remains at maximum tON as long as the inductor peak current limit is not reached as shown in plot C in Figure 1. The inductor peak current limit can be programmed by tying a resistor R

from the R

LIM

pin to

ground where:

= 1600 / R

PEAK

LIM

Inductor Current vs. Load

Ton Max. Toff Min.

Ton Max.

Toff Min.

Ton Max.

Toff Min.

Ton Max.

Toff Min.

E. Iripple=Toff* (Vo

Toff Min.

- Vi)/L<Iripple<Ton*Vi/L

D. Toff*= (Vo

C. Iripple=Ton*Vi/L

B. Iripple=Ton*Vi/L

A. Iripple=Ton*Vi/L

- Vi)/L

llim

Figure 1. Inductor Current vs. Load

which ends the charge cycle and starts the discharge cycle. However, full load is not yet achieved because at the end of the minimum discharge time the output was still within regulation.

Maximum load is reached when this discharge time has shrunk to the minimum allowed value T

as shown in Plot E of Figure 1.

OFF

When the peak current limit is reached the charge time is short-cycled.

In plot D of Figure 1, the switch current reaches the peak current limit during the charge period

Page 6

TYPICAL PERFORMANCE CHARACTERISTICS

Refer to the Typical Application Circuit on page 1, T

100

Efficiency (%)

0.1 1.0 10.0 100.0 1000.0

Iload (mA)

Efficiency vs. Load Current, V

OUT

3.400

3.380

3.360

3.340

3.320

(V)

3.300

OUT

3.280

3.260

3.240

3.220

3.200 0 100 200 300 400 500

(mA)

LOAD

Line/Load Rejection vs. Load Current, V

=3.3V

Vi=3.0V Vi=2.6V Vi=2.0V Vi=1.3V Vi=1.0V

OUT

= 3.3V

=+25°C.

AMB

100

Efficiency (%)

0.1 1.0 10.0 100.0 1000.0

Efficiency vs. Current Load, V

5.100

5.080

5.060

5.040

5.020

5.000

Vout (V)

4.980

4.960

4.940

4.920

4.900 0 100 200 300 400 500

Iload (mA)

=5.0V

OUT

Iload (mA)

Line/Load Rejection vs. Load Current, V

OUT

Vi=4.2V Vi=3.2V Vi=2.6V Vi=2.0V Vi=1.6V Vi=1.0V

= 5.0V

100

Iin (uA)

1.0 1.5 2.0 2.5 3.0

No Load Battery Current, V

OUT

Vin (V)

=3.3V

300

250

200

150

Iin (uA)

100

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

No Load Battery Current, V

Vin (V)

OUT

=5.0V

Page 7

TYPICAL PERFORMANCE CHARACTERISTICS

Refer to the Typical Application Circuit on page 1, T

400

350

300

250

200

Io (mA)

150

100

1.0 1.5 2.0 2.5 3.0

Maximum Resistive Load Current in Startup, V

Vin (V)

OUT

=3.3V

(AC)

=+25°C.

AMB

500

450

400

350

300

250

Io (mA)

200

150

100

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

Vin (V)

Maximum Resistive Load Current in Startup, V

OUT

=5.0V

OUT

(AC)

=200mA, V

LOAD

Vin (V)

Inductor Current (0.2A/DIV)

OUT

=5.0V

Inductor Current (0.2A/DIV)

Output Ripple, VIN=2.6V, I

5.0

4.0

3.0

2.0

Kon (V*usec)

1.0

0.0

0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3

KON vs. V

, V

=3.3V KON vs. V

OUT

=200mA, V

LOAD

Vin (V)

OUT

=3.3V

Output Ripple, VIN=2.6V, I

5.0

4.0

3.0

2.0

Kon (V*usec)

1.0

0.0

0.9 1.4 1.9 2.4 2.9 3.4 3.9 4.4 4.9

, V

=5.0V

OUT

Page 8

TYPICAL PERFORMANCE CHARACTERISTICS

Refer to the Typical Application Circuit on page 1, T

2.0

AMB

=+25°C.

2.0

1.5

1.0

Koff (V*usec)

0.5

0.0

0.9 1.2 1.5 1.8 2.4 2.7 3.0 3.3

2.1

Vin (V)

vs. V

, V

OFF

=3.3V

OUT

(1A/div)

1.5

1.0

Koff (V*usec)

0.5

0.0

0.9 1.4 1.9 2.4 2.9 3.4 3.9 4.4 4.9

vs. V

, V

OFF

=5.0V

OUT

Vin (V)

OUT

IIN(1A/div)

Startup, VIN=2.6V, V

Load Step, 0.1A to 0.3A, V

=3.3V, R

OUT

= 2.6V, V

LOAD

= 100Ω

= 3.3V

OUT

(AC)

(0.2A/div)

Startup, VIN=4.2V, V

=5.0V, R

OUT

Load Step, 0.3A to 0.5A, V

= 4.2V, V

LOAD

= 100Ω

= 5.0V

OUT

(AC)

(0.5A/DIV)

Page 9

APPLICATIONS INFORMATION

Circuit Layout

Printed circuit board layout is a critical part of a power supply design. Poor designs can result in excessive EMI on the feedback paths and on the ground planes with applications involving high switching frequencies and large peak currents. Excessive EMI can result in instability or regulation errors. All power components should be placed on the PC board as closely as possible with the traces kept short, direct, and wide (>50mils or 1.25mm). Extra copper on the PC board should be integrated into ground as a pseudo-ground plane. On a multilayer PC board, route the star ground using component-side copper fill, then connect it to the internal ground plane using vias. For the SP6648 devices, the inductor and input and output filter capacitors should be soldered with their ground pins as close together as possible in a star-ground configuration. The V

pin must be bypassed di-

OUT

rectly to ground as close to the SP6648 devices as possible (within 0.2in or 5mm). The DC-DC converter and any digital circuitry should be placed on the opposite corner of the PC board as far away from sensitive RF and analog input stages. Noisy traces, such as from the LX pin, should be kept away from the voltage-feedback V

node and separated from it using grounded

OUT

copper to minimize EMI. See the SP6648EB Evaluation Board Manual for PC Board Layout design details.

Component Selection

Selection of capacitors for SP6648 power supply circuits can be made through the use of the Component Selection Table. Capacitor equivalent series resistance (ESR) in the range of 0.2Ω to 0.3Ω is a requirement for obtaining sufficient output voltage ripple for the SP6648 to properly regulate under load. For ESR values in this range, low ESR Tantalum capacitors are recommended. For example, in the SP6648 application circuit a 47µF, 10V, low-ESR, surfacemount tantalum output filter capacitor typically provides 50mV output ripple when stepping up from 2.6V to 3.3V at 200mA. Ceramic capacitors have ESR too low to produce enough output

ripple for the SP6648 to regulate the output. Designers should select input and output capacitors with a rating exceeding the inductor current ripple, which is typically set by the inductor value and the KON value as given in the following relationship:

L(RIPPLE)

= KON/L

For the example of the 10µH inductor the inductor current ripple would be 330mA, while for the 22µH inductor the inductor current ripple value would be 150mA. Do not allow tantalum capacitors to exceed their ripple-current ratings. An input filter capacitor can reduce peak currents drawn from the battery and improve efficiency. For most applications, use the same 47µF tantalum capacitor as used for the input. Low-ESR aluminum electrolytic capacitors are acceptable provided they meet the ESR requirement of 0.2Ω to 0.3Ω, and we list an appropriate 100µF aluminum electrolytic in the component selection table, but standard aluminum electrolytic capacitors are not recommended.

In selecting an inductor, the saturation current specified for the inductor needs to be greater then the SP6648 peak current to avoid saturating the inductor, which would result in a loss in efficiency and could damage the inductor. The SP6648 evaluation board uses a Sumida CDRH5D28 10µH inductor with an I

SAT

value of 1.3A and a DCR of 0.065Ω, which easily handles the I

of 0.85A of the SP6648 and

PEAK

will deliver high efficiencies. Other inductors could be selected provided their I than the I

of the SP6648.

PEAK

is greater

SAT

Page 10

APPLICATIONS INFORMATION: Continued

INDUCTORS - SURFACE MOUNT

Inductor Specification

Inductance Manufacturer/Part No. Series R I

(µH)

10 Sumida CDRH5D28-100 0.065 1.30 5.7x5.5x3.0 Shielded Ferrite Core www.sumida.com

10 TDK RLF5018T-100MR94 0.067 0.94 5.6x5.2x2.0 Shielded Ferrite Core www.tdk.com

10 Sumida CD43-100 0.180 1.04 4.0x4.5x3.5 Unshileded Ferrite Core www.sumida.com

22 Sumida CDRH5D28-220 0.122 0.90 5.7x5.5x3 Shileded Ferrite Core www.sumida.com

22 TDK RLF5018T-220MR63 0.067 0.63 5.6x5.2x2.0 Shielded Ferrite Core www.tdk.com

22 Sumida CD43-220 0.378 0.68 4.0x4.5x3.5 Unshielded Ferrite Core www.sumida.com

Ω

SAT

(A) (mm) Website

CAPACITORS - SURFACE MOUNT & LEADED

Capacitance Manufacturer Part No. ESR Ripple Current Size LxWxH Voltage Capacitor Manufacturer

(

47 Kemet T494C476K010AS 0.300 1.06 6.0x3.2x2.5 10 SMT Tantalum www.kemet.com

47 Kemet T494V476K010AS 0.300 0.99 7.3x4.3x2.0 10 SMT Tantalum www.kemet.com

100 Sanyo 25MV100AX 0.220 0.30 6.3DX11L 25 Radial Al Electrolytic www.sanyovideo.com

Note: Components highlighted in bold are those used on the SP6648EB Evaluation Board.

Ω

(max) (A) @ 85°C (mm) (V) Type Website

Component Selection Table

Size LxWxH Intuctor Type Manufacturer

Capacitor Specification

BATT

549K

LBON

249K

SP6648EB Evaluation Board Schematic

47µF

LIM

1.87K

R51.0M

U1 SP6648

BATT

LBI

LBON

LIM

SHDN

10µH

GND

3.3V

47µF

OUT

GND

1µF

205K

47pF

124K

Page 11

Programming

OUT

The SP6648 can be programmed as either a voltage source or a current source. To program the SP6648 as voltage source, the SP6648 requires 2 feedback resistors R1 & R2, as shown in the SP6648EB evaluation board schematic, to control the output voltage. To set V

OUT

in the

voltage mode, use the equation:

R1 = [(V

/1.25)-1] * R2

OUT

APPLICATIONS INFORMATION : Continued

output goes low as determined by the relationship:

LOWBATT

= 0.61 * [(R3 + R4)/R4]

The SP6648 evaluation board R3 & R4 resistors have been set to trip for a falling battery threshold of about 2.0V. Using this relationship, other low battery threshold values can be set by the user.

Using the R

The peak inductor current, I externally by the R tween the R

Function

LIM

, is programmed

PEAK

resistor connected be-

LIM

pin and GND. The peak inductor

LIM

current is defined by:

= 1600/R

PEAK

LIM

The saturation current specified for the inductor needs to be greater than the peak current to avoid saturating the inductor, which would result in a loss in efficiency and could damage the inductor. The SP6648 evaluation board uses a R value of 1.87K for an I

= 850mA to allow

PEAK

LIM

the circuit to deliver up to 180mA for 1.3V input and 400mA for 2.6V input. Other values could be selected using the above relationships.

Using the LBON - Low Battery Output Function

The SP6648 will regulate the output until the input battery is completely discharged or until the under voltage lock-out (UVLO) occurs at V

= 0.61V. To provide a low battery warn-

BATT

ing, the Low Battery Output function of the SP6648 can be used. LBON is programmed externally by the R3 and R4 resistor divider connected between V

, the LBI input pin

BATT

and GND. The LBON is an open drain output, which is active low and is pulled up by a 1M resistor R5 to V

. When the LBI comparator

OUT

falling threshold of 0.61V is reached, the LBON

UVLO the Under Voltage Lock-Out Function

Once started up, the SP6648 will regulate the output until the input battery is completely discharged or until the under voltage lock-out (UVLO) occurs at V

= 0.61V. The UVLO

BATT

function will completely open all switches until the battery again rises above the 0.61V threshold.

Maximum Startup Current

It should be noted that for low input voltages the SP6648 startup circuit can not support large load currents at startup. In startup the SP6648 needs to boost the output from zero volts using the input voltage. Once the output is greater than

1.9V the operate circuit takes over and the SP6648 can supply much more current. Curves of maximum load current in startup for the SP6648 are shown in the typical performance characteristics and can be compared with the page one curve for maximum load current in operation.

For 1-cell battery applications, it is recommended to apply any large load current after the SP6648 has started up, typically in a few milliseconds. This is typically not a problem in many applications where the load is a processor whose load current is low until the processor voltage comes up.

Page 12

APPLICATIONS INFORMATION

SP6648LEDEB Evaluation Board with LumiLED High Brightness White LED

For the high brightness LumiLED white LED application, the SP6648 is generally programmed as a current source. The bias resistor R

is used

to set the operating current of the white LED as equation:

= V

REF/IF

BATT

1.8-3.2V

C1 10µF

LIM

1.87K

10µH

BATT

SP6648

LBI

LBON

LIM

SHDN

GND

OUT

where V

is around 0.61V, IF is the operating

REF

current of the LumiLED. To set the operating current to be about 350mA, Rb is selected as 1.8 Ω as shown in the following schematic. The efficiency of the SP6648 LumiLED circuit is improved by the use of a silicon diode D1 and resistor R1 to set the voltage at the current sense resistor R2 to 0.61V instead of the higher 1.25V at the FB pin. An efficiency curve follows showing the SP6648 efficiency driving 350mA output current into the high brightness LumiLED.

Important: 1µF Ceramic Cap at V needed for stable regulation

C4 1µF

16.2k

OUT

10K

(R5 optional)

=0.61V/R

OUT

D1 1N4148

C2 10µF

D2 1W LED 350mA

REF

1.8Ω

= 0.61V

SP6648LEDEB Evaluation Board Schematic

100

Efficiency (%)

1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2

Battery Voltage (V)

As shown in following scope photos, if the SP6648 is powered up before the LumiLED is plugged in, the circuit will bring the Feedback pin to 0V and the SP6648 has a feature to set the output voltage to be 3.3V. Once the LumiLED is plugged in, the Feedback pin will go up to 1.25V and begin to regulate. The output voltage will go from 3.3V to 3.68V (=VF+0.61V), where VF is the forward voltage of the LumiLED. When the LumiLED is open, the Feedback pin voltage will go to 0V and the output voltage will go to

3.3V which will protect the part.

SP6648LEDEB Efficiency Curve

Page 13

APPLICATIONS INFORMATION

OUT

REF

OUT

REF

Plug in the LumiLED

Brightness Control

One approach to control LED brightness is to apply a PWM signal to the SHDN input of the SP6648. In this case, the output current will be equal to the product of 350mA and the average duty cycle at the SHDN pin. An optional 10K potentiometer (R5) may also be used for dimming the LED current by varying the potentiometer between low brightness and full brightness.

BATT

LBON

LIM

SHDN

LBI

SP6648

10 Pin DFN

OUT

GND

Unplug the LumiLED

BATT

LBI

LBON

10 Pin MSOP

LIM

SHDN

SP6648

PINOUTS

OUT

GND

Page 14

PACKAGE: 10 PIN MSOP

Ø1

E/2

Seating Plane

Pin #1 indentifier must be indicated within this shaded area (D/2 * E1/2)

10 Pin MSOP JEDEC MO-187 (BA) Variation

SYMBOL

MIN NOM MAX

A--1.1 A1 0 - 0.15 A2 0.75 0.85 0.95

b 0.17 - 0.27

c 0.08 - 0.23

E E1

e e1

3.00 BSC

4.90 BSC

3.00 BSC

0.50 BSC

2.00 BSC

L 0.4 0.6 0.8 L1 L2

0.95 REF

0.25 BSC N-10R 0.07 - -

R1 0.07 - -

ø0º-8º

ø1 0º - 15º

Note: Dimensions in (mm)

Ø1

WITH PLATING

Gauge Plane

BASE METAL

Section B-B

Page 15

Top View

D/2

PACKAGE: 10 PIN DFN

E/2

Side View

3x3 10 Pin DFN JEDEC MO-229 (VEED-5)

VARIATION

SYMBOL

MIN NOM MAX

A 0.8 0.9 1 A1 0 0.02 0.05 A2 0.55 0.65 0.8 A3

0.20 REF b 0.18 0.25 0.3 D

3.00 BSC

D2 2.2 2.7

e E

0.5 PITCH

3.00 BSC

E2 1.4 - 1.75

K 0.2 - -

L 0.3 0.4 0.5

Note: Dimensions in (mm)

Bottom View

Page 16

ORDERING INFORMATION

Part Number Top Mark Operating Temperature Range Package Type

SP6648EU ................................ SP6648EU..................-40°C to +85°C ...................................... 10 Pin MSOP

SP6648EU/TR .......................... SP6648EU..................-40°C to +85°C..................................... 10 Pin MSOP

SP6648ER ............................... SP6648ERYWW..........-40°C to +85°C ........................................ 10 Pin DFN

SP6648ER/TR ......................... SP6648ERYWW..........-40°C to +85°C ....................................... 10 Pin DFN

Available in lead free packaging. To order add "-L" suffix to part number.

Example: SP6648EU/TR = standard; SP6648EU-L/TR = lead free

/TR = Tape and Reel

Pack quantity is 2,500 for MSOP and 3,000 for DFN.

CLICK HERE TO ORDER SAMPLES

Corporation

ANALOG EXCELLENCE

Sipex Corporation

Headquarters and Sales Office

233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600

Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.