Datasheet SC605 Datasheet (SEMTECH)

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1

POWER MANAGEMENT

SC605

Charge Pump

Flash LED Driver

December 1, 2005

Description

Features

Typical Application Circuit

Features

Typical Application Circuit

Applications

The SC605 is a high-current charge pump designed spe­cically for use with white LEDs used in camera ash ap­plications. Only two small bucket capacitors are required

to develop the output drive, providing a low EMI solution

compared to inductive boost regulators.

The SC605 has two modes of operation: Flash mode and
Spotlight mode. In Flash mode, the SC605 is capable of
delivering 500mA of regulated current for a duration of
500ms or up to 700mA for a reduced duration. In Spotlight
mode the SC605 can output 20%, 30%, or 40% of the Flash

mode current and remain enabled continuously.

An external resistor is connected in series with the LED to
set the current. In Flash mode, this resistor can dissipate

up to 0.175mW, reducing the power dissipation require

-

ment of the SC605. The Flash input (FLASH) overrides
the control inputs (CTRL0 and CTRL1) to ensure the Flash
function has the highest priority.

The thermally efcient MLPD-12 package and ceramic

bypass and bucket capacitors help make the SC605 a
high output current driver that requires a minimal amount

of PCB area.

Two selectable modes - Flash and Spotlight
Up to 700mA output - Flash mode
Up to 280mA output - Spotlight mode
500mA output over specied temperature and volt-

age ranges - Flash mode

Spotlight mode selectable to 20%, 30%

and 40% of Flash current

3.0V to 5.25V input range
Flash control pin for synchronization to

a camera module or graphics controller
Short circuit, over-voltage and
over-temperature protection

Soft-start functionality
Three control inputs for maximum versatility
Shutdown current < 2μA
Micro-lead package MLPD-12, 3mm x 3mm

VBAT

10µF

1µF

white LED

CTRL1

CTRL0

FLASH

0.5W

SC605

VIN

1

FLASH

6

CTRL0

8

CTRL1

9

NC

5

VOUT

11

ISET

7

C1+

10

C1-

4

C2+

12

C2-

2

1µF

1µF

GND

3

Mobile Camera Phones
Digital Cameras
PDAs with Built-in Cameras

查询SC605EVB供应商

2

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SC605

Absolute Maximum Ratings

Electrical Characteristics

Absolute Maximum Ratings

Exceeding the specications below may result in permanent damage to the device or device malfunction. Operation outside the parameters specied in the
Electrical Characteristics section is not implied. Exposure to Absolute Maximum rated conditions for extended periods of time may affect device reliability.

Parameter Symbol Maximum Units

Supply Voltage

V

IN

-0.3 to 6.5 V

Output Voltage

V

OUT

-0.3 to 6.5 V

Pin Voltage - FLASH, CTRL0, CTRL1, ISET, C1-, C2-

-0.3 to VIN + 0.3 V

Pin Voltage - C1+, C2+

-0.3 to V

OUT

+ 0.3 V

V

OUT

Short Circuit Duration

SC Indenite

Thermal Resistance, Junction to Ambient
(JESD51 Standard Method)

(1)

θ

JA

40 °C/W

Operating Ambient Temperature Range

T

A

-40 to +85 °C

Junction Temperature Range

T

JC

-40 to +150 °C

Storage Temperature Range

T

STG

-65 to +150 °C

IR Reow Temperature

T

LEAD

260 °C

ESD Protection Level

(2)

V

ESD

2 kV

Notes:

1) Calculated from package in still air, mounted to 3” x 4.5”, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.

2) Tested according to JEDEC standard JESD22-A114-B

Unless otherwise specied: TA = 25°C for TYP, -40°C to +60°C for MIN and MAX; C

IN

= 10µF, C

BUCKET

= C

OUT

= 1.0µF (ESR < 0.1Ω);

VIN = 3.0V to 5.25V; V

OUT

= 2.8V to 4.25V; R

ISET

= 0.5Ω 0.1%.

Parameter Symbol Conditions Min Typ Max Units

Flash Mode ­Output Current

I

OUT

FLASH high, R

ISET

= 0.357W,

3.7V < V

IN

< 4.2V, V

OUT

= 3.7V

(1)

700

mA

FLASH high, R

ISET

= 0.5W,

3.3V < VIN < 4.2V, 2.8V < V

OUT

< 4.25V

460 500 540

FLASH low, CTRL0 high, CTRL1 high, R

ISET

=

0.357W, 3.7V < VIN < 4.2V, V

OUT

= 3.4V

(1)

280

Spotlight Mode ­Output Current

I

OUT

FLASH low, CTRL0 high, CTRL1 high, R

ISET

=

0.5W, 3.0V < VIN < 4.5V, 2.8V < V

OUT

< 4.5V

170 200 230

FLASH low, CTRL0 low, CTRL1 high, R

ISET

=

0.5W, 3.0V < VIN < 4.5V, 2.8V < V

OUT

< 4.5V

120 150 180

(2)

FLASH low, CTRL0 high, CTRL1 low, R

ISET

=

0.5W, 3.0V < VIN < 4.5V, 2.8V < V

OUT

< 4.5V

70 100 130

(2)

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SC605

Electrical Characteristics (Cont.)

Parameter Symbol Conditions Min Typ Max Units

Flash Mode ­ISET Reference Voltage

V

ISET

FLASH high, R

ISET

= 0.5W,

3.3V < VIN < 4.2V, 2.8V < V

OUT

< 4.25V

230 250 270

mV

Spotlight Mode ­ISET Reference Voltage

V

ISET

FLASH low, CTRL0 high, CTRL1 high

3.0V < VIN < 4.5V, 2.8V < V

OUT

< 4.5V

85 100 115

FLASH low, CTRL0 low, CTRL1 high

3.0V < VIN < 4.5V, 2.8V < V

OUT

< 4.5V

60 75 90

(3)

FLASH low, CTRL0 high, CTRL1 low

3.0V < VIN < 4.5V, 2.8V < V

OUT

< 4.5V

35 50 65

(3)

Quiescent Current

I

Q

FLASH High 3.4 5 mA

FLASH low, CTRL0 and/or CTRL1 High 2.0 4.5 mA

FLASH low, CTRL0 low, CTRL1 Low 0.1 2 µA

Flash Mode
Pulse Duration

(4)

t

FLASH

3.3V < VIN < 4.2V
I

OUT

= 500mA

500 ms

Flash Mode
Start-Up Time

(4)

t

F-ST

from t = 0 when FLASH goes high to

I

OUT

= 90% of nal value

1 ms

Spotlight Mode
Start-Up Time

(4)

t

S-ST

from t = 0 when CTRL0 and/or CTRL1 transi-

tion high to I

OUT

= 90% of nal value

1 ms

Oscillator Frequency f

OSC

Device Enabled 250 kHz

Oscillator Frequency
Accuracy

Df

OSC

-15 15 %

Short-Circuit Ouput
Current Limit

I

SC

V

OUT

= 0V 465 mA

Input Current Limit I

LIMIT

3.3V < VIN < 4.2V 1.0 2.1

A

VIN = 3.7V, V

OUT

= 3.7V, TA = 25°C 1.38 1.53

Over-Temperature
Protection

(4)

T

OT

150 °C

Hysteresis 10 °C

Logic Input High Threshold V

IH

FLASH, CTRL0, CTRL1 1.5 V

Logic Input Low Threshold V

IL

FLASH, CTRL0, CTRL1 0.4 V

Logic Input High Current IIH FLASH, CTRL0, CTRL1 1 20 35 µA

Logic Input Low Current I

IL

FLASH, CTRL0, CTRL1 0.1 2 µA

ISET Ripple Voltage

(4)

V

PP

Spotlight Mode, I

OUT

= 200mA 25

mV

Flash Mode, I

OUT

= 500mA 100

Notes:
(1) V

OUT

required by the typical LED at this current.
(2) Values do not overlap with the next higher spotlight mode for any single device. Expect Spotlight Modes to be separated by about 50mA.
(3) Values do not overlap with the next higher spotlight mode for any single device. Expect Spotlight Modes to be separated by about 25mV.
(4) Guaranteed by design - not tested in production.

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SC605

Pin Conguration

Pin Conguration Ordering information

Pin Descriptions

DEVICE PACKAGE

SC605MLTRT

(1)(2)

MLPD-12 3x3

SC605EVB Evaluation Board

Notes:
(1) Available in Tape and Reel only. A reel contains 3000

devices.

(2) Available in lead-free package only. This product is fully
WEEE and RoHS compliant.

Pin Pin Name Pin Function (also see Suggested Layout guidelines on page 10)

1 VIN Input voltage. Decouple with a 10µF or larger ceramic capacitor near pin 1.

2 C2- Negative terminal of bucket capacitor 2 - use a 1µF ceramic capacitor.

3 GND Ground - connect through multiple vias to the ground plane.

4 C1- Negative terminal of bucket capacitor 1 - use a 1µF ceramic capacitor.

5 NC Not connected - leave this pin oating.

6 FLASH Flash mode enable pin - puts the device in active Flash mode when high.

7 ISET Current-setting reference pin - connect to the LED cathode and the current setting resistor.

8 CTRL0 Control input bit 0 - used with CTRL1 to enable and set the output current in Spotlight mode (see Table 1).

9 CTRL1 Control input bit 1 - used with CTRL0 to enable and set the output current in Spotlight mode (see Table 1).

10 C1+ Positive terminal of bucket capacitor 1 - use a 1µF ceramic capacitor.

11 VOUT Output pin - connect to LED anode. Decouple with a 1µF ceramic capacitor near pin 11.

12 C2+ Positive terminal of bucket capacitor 2 - use a 1µF ceramic capacitor.

T Thermal Pad Pad for heat sinking purposes - not connected internally. Connect to ground plane using multiple vias.

TOP VIEW

1

2

3

4

5

MLPD - 12: 3X3 12 LEAD

T

6

12

11

10

9

8

7

VIN

C2-

GND

C1-

NC

FLASH ISET

CTRL0

CTRL1

C1+

VOUT

C2+

5

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SC605

Applications Information

General Operation

The SC605 is a powerful 2x charge pump designed to drive
a high-intensity white LED with a constant current (Spotlight
mode) or with a pulsed current of higher intensity (Flash
mode) used for camera ash.

In Flash mode the SC605 output can drive 500mA at 4.25V
into an LED for up to 500ms. The FLASH pin is used to
trigger Flash mode. In spotlight mode the SC605 regulates
the output current to the value selected by the CTRL0 and
CTRL1 inputs. Note that Flash mode has priority over
Spotlight mode, i.e., the FLASH pin triggers Flash mode
regardless of the state of the CTRL0 and CTRL1 pins.

Output current is regulated by attaching the ISET pin to the
cathode(s) of the LED package and a load sense resistor
(typically 0.5W). The ISET pin monitors the voltage at the

cathode and signals the charge pump to increase or de-

crease the output current until the ISET voltage reaches
the programmed setting. Programmed settings are shown
in Table 1:

CTRL1 CTRL0 FLASH V

ISET

Mode

0 0 0 0mV Disabled

0 1 0 50mV Spotlight

1 0 0 75mV Spotlight

1 1 0 100mV Spotlight

x x 1 250mV Flash

Table 1 - Control State Table

The resistor value is chosen to set the current through the

LED based on this reference voltage. The resistor should

not be less than 0.35W due to the output current limitations

of the device. Note that the resistor sets both the Flash

mode current and the Spotlight mode current.

In Flash mode, I

OUT

= V

ISET

/ R

ISET

= 250mV / R

ISET

.

In Spotlight mode, I

OUT

= V

ISET

/ R

ISET

.

Spotlight Mode

Spotlight mode is enabled by setting the CTRL0 and CTRL1

pins as shown in Table 1. When in Spotlight mode, the

SC605 can maintain a constant current indenitely to drive
an LED or bank of LEDs. The ISET pin voltage is the refer-

ence V

ISET

and has three different settings - 50mV, 75mV,

and 100mV. These settings allow the designer the exibility

to select the output level needed to suit the application.

Flash Mode

Flash mode is enabled whenever the FLASH pin is pulled
high and remains active until the FLASH pin is released.
While in Flash mode the reference voltage on the ISET pin

is set to 250mV. During Flash mode the charge pump de-

velops enough output current to drive an LED with 500mA
for a duration up to 500ms. The duration of the pulse is
limited by the amount of power that can be dissipated in
the SC605 before it exceeds the maximum operating tem­perature. Note that if an output current less than the rated
500mA is desired the duration of the pulse can increase
proportionally. However, great care should be taken to in­sure the FLASH pin is not held high for an extended amount
of time so that overheating does not occur. Extending ash
mode beyond the 500ms pulse limit could adversely affect
the long-term reliability of the SC605. Flash duration must
be derated at higher currents, for example, 700mA derates
to a maximum of 350ms. The plot below shows maximum
Flash mode current for extended duration times.

Maximum Flash Duration

Protection Circuitry

The SC605 also provides protection circuitry that prevents

the device from operating in an unspecied state. These
include Input Over-Voltage Protection (IOVP), Output Over­Voltage Protection (OVP), Over-Temperature Protection
(OTP), Over-Current Protection (OCP), and Short-Circuit
Current Protection (SCCP).

Input Over-Voltage Protection

Input over-voltage protection is included to prevent opera­tion at high input voltages that could damage the device.

The IOVP circuit senses the input voltage and determines

when the supply exceeds 6V. When the voltage rises
above this threshold, the device is disabled until the input

voltage drops to a level within the specied input range.
Hysteresis is included in this circuit to avoid chattering

between states.

0

100

200

300

400

500

600

700

800

0 500 1 000 1500 2000

Flash Duration [ms]

Flash Current [mA]

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SC605

Applications Information (Cont.)

Output Over-Voltage Protection

Output over-voltage protection is included to prevent the

SC605 from generating an output voltage that could dam­age other devices connected to it such as load LEDs and

bypass capacitors. When the output voltage exceeds 5.5V,

the OVP circuit disables the charge pump until the voltage

decreases to a level within the acceptable range. This cir-

cuit allows the device to drive LEDs with high forward volt

ages at a reduced level without exceeding the output volt-

age limits specied for the device. This is a consequence
of over-voltage protection, not the function of OVP.

Over-Temperature Protection

The OT circuit helps prevent the device from overheating
and experiencing a catastrophic failure. When the junction
temperature exceeds 150°C the device is disabled. It
remains disabled until the junction temperature drops
below this threshold. As with the OVP circuit, hysteresis is

included to prevent toggling between states.

Over-Current Protection

When the SC605 is in 2X charge pump mode, the input

current will be approximately double the required output.
When the steady-state load requires the maximum current

available in 2X mode, the OCP circuit prevents the device
from overheating due to excessive power dissipation.

Short-Circuit Current Protection

SCCP is provided to limit the current that can be sourced

when the output is shorted to ground. When the output

voltage drops below 2V, the SCCP detects the condition as

a short to ground and limits the output current.

Resistor Selection

The ISET resistor selection is critical to generating the cor­rect current. The value can be chosen to set the Spotlight
mode current or the Flash mode current, but it must be
noted that the two current settings are dependent on the

same resistor. It is recommended that the resistor be se­lected to match the LEDs desired current for Flash mode.

This will allow the designer to set the maximum current

out of the SC605. The typical application circuit shown on

page 1 uses a 0.5

W resistor to set a Flash mode current

of 500mA and Spotlight mode options of 100mA, 150mA,

and 200mA. A precision resistor should be used to ensure

the specied accuracy for LED current.

To avoid malfunction of the charge pump, it is recom­mended that the resistance seen at the ISET pin remain
constant while the device is active (Flash or Spotlight
mode). Changing the resistance value or the load current

while the device is active could cause instability or voltage
transients that would result in non-compliant behavior.

The load current return path is from the ISET sense point
through the resistor and back to the ground pin. Resistance
in this path adds to the total resistance and has the effect
of reducing the LED current by about 4% per 10mV of DC

drop across the return copper trace in Flash mode. For this
reason, it is crucial to have a low resistance return path.

Place and ground the resistor as close as possible to the
ground pin of the SC605. The trace from ISET has virtually
no current. The ISET trace should make contact at the pad
of the power sense resistor to minimize the effect of voltage
drop between the LED cathode and the resistor.

Capacitor Selection

The SC605 is designed to use low-ESR ceramic capaci­tors for the input and output bypass capacitors as well as
the charge pump bucket capacitors. Ideal performance
is achieved when C1 is exactly equal to C2. It is recom­mended that X5R or X7R ceramic capacitors be used for
best performance.

Thermal Resistance

The SC605 package is thermally efcient when the circuit

board layout connects the thermal pad through multiple
vias to the ground plane. The thermal resistance is rated
at 40°C/W, but this rating is dependent on the connection
between the thermal pad and the ground plane. A layout
that is done correctly should keep the junction tempera­ture below the OT limit while operating the SC605 within

the specifed electrical conditions for I

OUT

and V

ISET

. A poor

layout may allow the junction temperature to reach the

OT limit while in Flash or Spotlight mode.

7

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SC605

Block Diagram

0.5W

1µF

1µF

1µF10µF

CHARGE

PUMP

VBAT

250kHz

Logic Control

Reference

Voltage

Generator

LDO

C1+

C1-

C2+

C2-

VOUT

ISET

VIN

CTRL0
CTRL1
FLASH

GND

NC

white LED

CTRL0

FLASH

CTRL1

Figure 1 - SC605 Block Diagram with Support Components

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SC605

675

695

715

735

755

0 100 200 300 400 500

Time [ms]

Current [mA]

VIN=4.2V

VIN=3.7V

VIN=3.3V

490

495

500

505

510

0 100 200 300 400 500

Pulse Duration [ms]

LED Current [mA]

VIN=4.2V

VIN=3.7V

VIN=3.3V

Typical Characteristics

Flash Duration, RISET=500mW,

VOUT=3.52V(start) to 3.38V(LED heated 500ms)

Flash Duration, RISET=350mW,

VOUT=3.62V (start) to 3.40V(LED heated 500ms)

200mA Spotlight Current, RISET=500m

W, VOUT=3.0V

187.5

192.5

197.5

202.5

207.5

212.5

3.00 3.45 3.90 4.35 4.80 5.25

VIN [V]

Current [mA]

Flash Current at 500ms, RISET= 500mW, VOUT=3.38V

460

480

500

520

540

3.30 3.45 3.60 3.75 3.90 4.05 4.20

VIN [V]

Current [mA]

Flash Current at 100ms, RISET=500mW, VOUT=3.46V

460

480

500

520

540

3.30 3.45 3.60 3.75 3.90 4.05 4.20

VIN [V]

Current [mA]

Flash Current at 10ms, RISET=500mW, VOUT=3.52V

460

480

500

520

540

3.30 3.45 3.60 3.75 3.90 4.05 4.20

VIN [V]

Current [mA]

9

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SC605

Typical Characteristics (Cont.)

Flash Current at 350ms, RISET=350mW, VOUT=3.45V

675

695

715

735

755

3.30 3.45 3.60 3.75 3.90 4.05 4.20

VIN [V]

Current [mA]

Flash Current at 100ms, RISET=350mW, VOUT=3.53V

675

695

715

735

755

3.30 3.45 3.60 3.75 3.90 4.05 4.20

VIN [V]

Current [mA]

Flash Current at 10ms, RISET=350mW, VOUT=3.62V

675

695

715

735

755

3.30 3.45 3.60 3.75 3.90 4.05 4.20

VIN [V]

Current [mA]

Flash Mode VISET Ripple

Ch1 100mV/div
Ch2 2V/div
Ch3 2V/div
4us/div

Startup Flash Mode 500mA

Ch1 100mV/div
Ch2 2V/div
Ch3 2V/div
40us/div

100mA Spotlight Current, RISET=500m

W, VOUT=2.92V

85.0

90.0

95.0

100.0

105.0

110.0

115.0

3.00 3.45 3.90 4.35 4.80 5.25

VIN [V]

Current [mA]

10

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SC605

Suggested Layout

The following layout is suggested for a two layer design with

one component side. The capacitors C1 and C2 are the
bucket capacitors and each of these capacitors conducts

the full load current of up to 700mA pulsed on for one half

clock cycle per capacitor. C3 is the output decoupling ca­pacitor, placed near the SC605. C4 is the input decoupling

capacitor, placed near the SC605. Multiple vias should be

used whenever it is necessary to change layers on nets

connecting to pins VIN, VOUT, GND, C1-, C1+, C2-, C2+.
Resistor R1 is routed with a very low resistance connection
between ISET and GND pin 3. The sense trace between
pin 7 and R1 is connected to R1 at the terminal pad for

the most accurate sensing possible.

The bottom copper layer is primarily a ground plane provid-

ing a return path between the ground vias at R1 and the

ground vias connecting pin 3 to the ground plane.

The SC605’s center thermal pad is tied to the ground plane
through a heat spreading copper shape with multiple vias.
There are 10 vias shown in this layout connecting the ther­mal pad and pin 3 together to the ground plane. All 10 vias
help spread heat and conduct ground current. Note that

the thermal pad does not conduct current. Pin 3 conducts
the full ground current.

Four signal traces routed on the bottom layer are CTRL1,
CTRL0, FLASH and ISET. These traces are routed horizon­tally on the bottom layer. Carefully route these traces so
they do no block the ground path from R1 to the ground

pin 3.

Top Copper Bottom Copper

11

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SC605

Outline Drawing - MLPD-12 Pin

Marking Information

NOTES:

CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).

COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS.

2.

1.

.003

.006

.042

12

.008

.048

.000

.031

(.008)

0.08

0.20

12

.010

.052

0.15

1.06

.039
.002 0.00

0.80

1.31

0.25

1.21

0.05

1.00

(0.20)

.004 0.10

0.45 BSC.018 BSC

0.30.012 .020.016 0.40

0.50

aaa

C

SEATING
PLANE

A

bbb C A B

B

e

C

.074 .079 .083 1.87 2.02

2.12

-

-

-

-

(LASER MARK)

INDICATOR

PIN 1

1N2

MIN

aaa
bbb

b

e
L

N

E1

D1

E

A1
A2

A

DIM

MILLIMETERS

NOM

DIMENSIONS

MAXNOM

INCHES

MIN MAX

.114

.118

.122

2.90 3.00 3.10

A1

A2

LxN

E1

D1

A

e/2

bxN

D .114

.118

.122

2.90 3.00 3.10

D

E

E/2

D/2

Top Marking

yyww = Datecode (Example: 0552)

xxxxx = Semtech lot number

605

yyww

xxxxx

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SC605

Land Pattern - MLPD-12 Pin

.087

.055

2.20

1.40

.150

.018
.010
.037

3.80

0.25

0.95

0.45

(.112)

.075 1.90

(2.85)

THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.

NOTES:

1.

THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD

SHALL BE CONNECTED TO A SYSTEM GROUND PLANE.

FUNCTIONAL PERFORMANCE OF THE DEVICE.

FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR

2.

INCHES

DIMENSIONS

G

K

H

X
Y

P

Z

C

DIM MILLIMETERS

H

K

G

Y

Z

P

(C)

X

Semtech Corporation

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Phone: [phone] FAX [phone]

Contact Information