Diodes ZXSC410, ZXSC420, ZXSC440 User Manual

ZXSC410/ZXSC420/ZXSC440

DC-DC BOOST SWITCHING CONTROLLERS

Description

The ZXSC410/420/440 are DC-DC boost controllers. Their wide input

voltage range make suitable for operation from a number of battery

configurations including single Li-Ion cell and 2~3 alkaline/NiCd/NiMH

cells. Using high gain Diodes Zetex-brand switching npn-transistors

allow high voltage boost ratios and/or high output current depending

on transistor. The ZXSC410/440 has a shutdown feature that can also

be used for some dimming functionality. ZXSC420/440 includes an

End of Regulation flag that can be used to indicate when the regulator

is no longer able to maintain the regulated output voltage/current or

has reached the required current/voltage. The ZXSC440 combines

the features of the ZXSC410 and ZXSC420 into one device.

Features

 1.65V to 8V Supply Range
 Typical Output Regulation of ±1%
 Over 85% Typical Efficiency
 Output Currents Up to 300mA
 4.5µA Typical Shutdown Current ZXSC410/440
 End of Regulation Output ZXSC420/440
 Available in SOT26 and MSOP-8
 Totally Lead-Free & Fully RoHS compliant (Notes 1 & 2)
 Halogen and Antimony Free. “Green” Device (Note 3)

Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.

2. See http://www.diodes.com for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free.

3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl)
and <1000ppm antimony compounds.

Pin Assignments

ZXSC410 (SOT26)

V

1

CC

GND

STDN

2
3

ZXSC420 (SOT26)

1

V

CC

GND
EOR

2
3

ZXSC440 (MSOP-8)

DRIVE

SENSE

VFB

N/C

1

2
3
4

Applications

 System Power for Battery Portable Products
 LCD Bias
 Local Voltage Conversion
 High Brightness LED Driving

8
7
6

DRIVE

8

VFB

7

SENSE

6

8

7
6
5

DRIVE
VFB
SENSE

V

CC

GND
EOR
STDN

Typical Applications Circuit

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

22µF

ZXSC410

www.diodes.com

22µH

ZXTN25012EFH

1 of 17

ZHCS2000

100µF

18m? 820m?

March 2013

© Diodes Incorporated

Pin Descriptions

ZXSC410/ZXSC420/ZXSC440

Pin Name

VCC

GND 2 2 7 Ground

STDN 3 — 5 Shutdown (ZXSC410 and ZXSC440)

EOR — 3 6 End of regulation (ZXSC420 and ZXSC440)

Sense 4 4 3

VFB

Drive 6 6 1

NC — — 4 No connection

ZXSC410 ZXSC420 ZXSC440

Pin Number

1 1 8 Supply Voltage

Inductor current sense input. Internal threshold voltage set to 28mV.
Connect external sense resistor.

5 5 2

Reference voltage. Internal threshold set to 300mV.
Connect external resistor network to set output voltage.

Drive output for external switching transistor.
Connect to base or gate of external switching transistor.

Functional Block Diagram

Function

ZXSC410/ZXSC420/ZXSC440

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ZXSC410/ZXSC420/ZXSC440

Absolute Maximum Ratings (@T

Parameter Rating Unit

VCC

Drive

EOR

STDN

-0.3 to +10 V

-0.3 to V

-0.3 to V

-0.3 to The lower of (+5.0) or (V

VFB, Sense -0.3 to The lower of (+5.0) or (VCC +0.3)

Operating Temperature -40 to +85 °C

Storage Temperature -55 to +120 °C

Power Dissipation @ +25°C 450 mW

Caution: Stresses greater than the 'Absolute Maximum Ratings' specified above, may cause permanent damage to the device. These are stress ratings only;
functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability may
be affected by exposure to absolute maximum rating conditions for extended periods of time.
Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when
handling and transporting these devices.

Recommended Operating Conditions (@T

Symbol Parameter Min Max Unit

VCC VCC Range

TA

VIH

VIL

Ambient Temperature Range

Shutdown Threshold

Shutdown Threshold

Electrical Characteristics (V

Symbol Parameter Conditions Min Typ Max Unit

IQ (Note 4)

I

STDN

EFF (Note 5)

ACC

REF

TCO

REF

T

DRV

F

OSC

Input Parameters

V

SENSE

I

SENSE

VFB

IFB (Note 6)

dVLN

Output Parameters

I

(Note 7)

OUT

I

DRIVE

V

DRIVE

C

DRIVE

V

OHEOR

V

OLEOR

T

EOR

dILD

Notes: 4. Excluding gate/base drive current.

5. Effective sense voltage observed when switching at approximately 100kHz. The internal comparator propagation delay of approximately 1µs causes an
increase in the effective sense voltage over a DC measurement of the sense voltage.

6. I

7. System not device specification, including recommended transistors.

Quiescent Current

Shutdown Current

Efficiency

Reference Tolerance

Reference Temp Co.

Discharge Pulse Width

Operating Frequency

Sense Voltage (Note 5)

Sense Input Current

Feedback Voltage

Feedback Input Current

Line Voltage Regulation

Output Current

Transistor Drive Current

Transistor Voltage Drive

MOSFET Gate Drive cpbty

EOR Flag Output High

EOR Flag Output Low

EOR Delay Time

Load Current Regulation

is typically half of these values at 3V.

FB

= +25°C, unless otherwise specified.)

A

CC

CC

+0.3

+0.3

CC

+0.3)

V

V

V

V

= +25°C, unless otherwise specified.)

A

1.8 8 V

-40 +85 °C

1.5

VCC

V

0 0.55 V

= 3V, @TA = +40°C to +85°C, unless otherwise specified.)

CC

VCC = 8V

220 µA

4.5 µA

50mA > I

> 300mA

OUT

1.8V < VCC < 8V

85 %

-3.0 +3.0 %

0.005 %/°C

1.8V < VCC < 8V

1.7 µs

200 kHz

22 28 34 mV

VFB = 0V; V

TA = +25°C

VFB = 0V; V

SENSE

SENSE

= 0V

= 0V

-1 -7 -15 µA

291 300 309 mV

-1.2 -4.5 µA

0.5 %/V

VIN > 2V, V

V

DRIVE

OUT

= 0.7V

1.8V < VCC < 8V

= VIN

300 mA

2 3.4 5 mA

0

V

-0.4

CC

300 pF

I

= -300nA

EOR

I

= 1mA

EOR

TA = +25°C

2.5

VCC

0 1.15 V

70 195 250 µs

0.01 %/mA

V

V

ZXSC410/ZXSC420/ZXSC440

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N

OLTAG

)

R

CUR

REN

T

)

Typical Characteristics

E (mV

SE V

SE

29.0

28.5

28.0

27.5

T = 25°C

A

T = -40°C

A

T = 85°C

A

8

7

6

5

4

SHUTDOWN CURRENT (µA)

3

ZXSC410/ZXSC420/ZXSC440

I = 0V

STDN

T = -40°C

A

T = 25°C

A

T = 85°C

A

27.0
18234567

INPUT VOLTAGE (V)

Input Voltage vs. Sense Voltage

3.6

T = 85°C

A

3.5

T = 25°C

A

2

182345 67

INPUT VOLTAGE (V)

Input Voltage vs. Shutdown Voltage

310

T = 25°C

A

(mA

T = -40°C

A

IVE
D

3.4

3.3

T = -40°C

A

300

T = 85°C

A

FEEDBACK VOLTAGE (mV)

3.2
18234567

INPUT VOLTAGE (V)

Input Voltage vs. Drive Current

290

18234567

INPUT VOLTAGE (V)

Input Voltage vs. Feedback Voltage

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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ZXSC410/ZXSC420/ZXSC440

Application Information

Functional Blocks

Bandgap Reference

All threshold voltages and internal currents are derived from a temperature compensated bandgap reference circuit with a reference voltage of

1.22V nominal.

Dynamic Drive Output

Depending on the input signal, the output is either “LOW” or “HIGH”. In the high state a 2.5mA current source (max drive voltage = VCC -0.4V)

drives the base or gate of the external transistor. In order to operate the external switching transistor at optimum efficiency, both output states

are initiated with a short transient current in order to quickly discharge the base or the gate of the switching transistor.

Switching Circuit

The switching circuit consists of two comparators, Comp1 and Comp2, a gate U1, a monostable and the drive output. Normally the DRIVE output

is “HIGH”; the external switching transistor is turned on. Current ramps up in the inductor, the switching transistor and external current sensing

resistor. This voltage is sensed by comparator, Comp2, at input I

20mV, comparator Comp2 through gate U1 triggers a re-triggerable monostable and turns off the output drive stage for 2s. The inductor

discharges to the load of the application. After 2s a new charge cycle begins, thus ramping the output voltage. When the output voltage reaches

the nominal value and VFB gets an input voltage of more than 300mV, the monostable is forced “on” from Comp1 through gate U1, until the

feedback voltage falls below 300mV. The above action continues to maintain regulation.

EOR, End of Regulation Detector (ZXSC420/440)

The EOR circuit is a retriggerable 120s monostable, which is re-triggered by every down regulating action of comparator Comp1. As long as

regulation takes place, output EOR is “HIGH“ (high impedance, 100K to V

the output voltage falls below the nominal value for more than 120s, output EOR goes ”LOW”. The reason for this to happen is usually a slowly

progressing drop of input voltage from the discharging battery. Therefore the output voltage will also start to drop slowly. With the EOR detector,

batteries can be used to the ultimate end of discharge, with enough time left for a safe shutdown. It can also be used in high-voltage photoflash

with the ZXSC440 to show when the capacitor is fully charged.

Shutdown Control

The ZXSC410/440 offers a shutdown mode that consumes a standby current of less than 5µA. The ZXSC410/440 is enabled, and is in normal

operation, when the voltage at the STDN pin is between 1V and 8V (and also open circuit). The ZXSC410/440 is shutdown with the driver

disabled when the voltage at the STDN pin is 0.7V or lower. The STDN input is a high impedance current source of 1µA typ. The driving device

can be an open-collector or -drain or a logic output with a “High” voltage of 5V max. The device shutdown current depends on the supply voltage,

see typical characteristics graph.The ZXSC440 with its STDN pin and EOR pins can be used as a camera flash driver.

The STDN pin is used to initiate the high voltage capacitor charge cycle. The EOR pin is used as flag to show when the capacitor has been

charged to the appropriate level.

A transformer is used to boost the voltage. If designing a transformer, bear in mind that the primary current may be over an amp and, if this flows

through 10 turns, the primary flux will be 10 Amp. Small number of turns and small cores will need an air gap to cope with this value without

saturation. Secondary winding capacitance should not be too high as this is working at 300V and could soon cause excessive losses.

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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. Once the current sense voltage across the sensing resistor exceeds

SENSE

). Short dips of the output voltage of less than 120s are ignored. If

CC

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ZXSC410/ZXSC420/ZXSC440

Application Information (cont.)

External Component Selection

Switching Transistor Selection

The choice of switching transistor has a major impact on the converter efficiency. For optimum performance, a bipolar transistor with low V

and high gain is required. The V

transistor is switched off. Diodes SOT26 transistors are an ideal choice for this application.

of the switching transistor is also an important parameter as this sees the full output voltage when the

CEO

Schottky Diode Selection

As with the switching transistor, the Schottky rectifier diode has a major impact on the converter efficiency. A Schottky diode with a low forward

voltage and fast recovery time should be used for this application.

The diode should be selected so that the maximum forward current rating is greater or equal to the maximum peak current in the inductor, and

the maximum reverse voltage is greater or equal to the output voltage. The Diodes ZHCS Series meet these needs.

Inductor Selection

The inductor value must be chosen to satisfy performance, cost and size requirements of the overall solution.

Inductor selection has a significant impact on the converter performance. For applications where efficiency is critical, an inductor with a series

resistance of 500m or less should be used.

Output Capacitors

Output capacitors are a critical choice in the overall performance of the solution. They are required to filter the output and supply load transient

currents. There are three parameters which are paramount in the selection of the output capacitors, capacitance, I

capacitance value is selected to meet the load transient requirements. The capacitors I

solution.

The ESR of the output capacitor can also affect loop stability and transient performance. The capacitors selected for the solutions, and indicated

in the reference designs, are optimised to provide the best overall performance.

rating must meet or exceed the current ripple of the

RIPPLE

and ESR. The

RIPPLE

Input Capacitors

The input capacitor is chosen for its voltage and RMS current rating. The use of low ESR electrolytic or tantalum capacitors is recommended.

Capacitor values for optimum performance are suggested in the reference design section.

Also note that the ESR of the input capacitor is effectively in series with the input and hence contributes to efficiency losses in the order of I

ESR.

Peak Current Definition

In general, the IPK value must be chosen to ensure that the switching transistor, Q1, is in full saturation with maximum output power conditions,

assuming worse case input voltage and transistor gain under all operating temperatureextremes.Once I

is decided the value of R

can be determined by:

SENSE

R

SENSE

V

SENSE



I

PK

PK

Sense Resistor

A low value sense resistor is required to set the peak current. Power in this resistor is negligible due to the low sense voltage threshold, V

CE(SAT)

RMS

SENSE

.

2

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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



ZXSC410/ZXSC420/ZXSC440

Application Information (cont.)

Output Power Calculation

By making the above assumptions for inductance and peak current the output power can be determined by:

P
where

and

and

and

t

and

 = efficiency i.e. 100% = 1

Operating frequency can be derived by:

Output Adjustment

The ZXSC410/420/440 are adjustable output controllers allowing the end user the maximum flexibilty. They can be used both as switching

voltage regulators and as constant current regulators. A feedback voltage of 300mV provides a good compromise for both voltage and current

regulation.

For a constant output voltage operation a potential divider network is connected as follows:

= IAV x VIN x  = (Watts)

OUT



I

PK



I

AV

2 

I

PK



t

ON

V

I

PK



t

DIS

 1.7s (internally set by ZXSC410/420/440)

OFF

1

f

tt

DISON

x



xL

IN

xL



VV

ININ

tt

OFFON

tt

OFFON

V

OUT

R

A

V

FB

R

B

GND

The output voltage is determined by the equation:

RA

where V

The resistor values, RA and RB, should be maximised to improve efficiency and decrease battery drain. Optimisation can be achieved by

providing a minimum current of I

Note: For the reference designs, RA is assigned the label R2 and RB the label R3.

The ZXSC410/420/440 can also be used to generate a constant current between boosted output rail and the VFB pin by connecting a single

resistor between VFB and GND.

VV

FBOUT

= 300mV

FB






ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2





1

RB




= 200nA to the VFB pin. Output is adjustable from VFB to the (BR)V

FB(MAX)

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of the switching transistor, Q1.

CEO

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Application Information (cont.)

LED Driving

The ZXSC410/420/440 make simple low voltage boost LED drivers.

The resistor value is determined by the following:

V

I

LED

FB



R

LED

ZXSC410/ZXSC420/ZXSC440

V

FB

R

LED

GND

Open-Circuit Protection

As a boost converter if the load (LED chain) should become open-circuit a Zener diode can be connected across the LED chain preventing over-

voltage and possible damage to the main switching transistor. The Zener diodes should be selected by ensuring its voltage rating is higher than

the combined forward voltage of the LED chain. Under open circuit conditions the current in the Zener diode defines the output current as:

V

FB

The circuit example below give an open circuit output

current of 300µA.



I

Z

R

Z

To

co nverter

ZD1

V

FB

R

Z

1k?

R

LED

GND

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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O

U

T

PUT CUR

REN

T

Application Information (cont.)

Dimming Control

There are many types of dimming control that can be implemented for the ZXSC410/420/440.

Dimming Control Using the Shutdown Pin

The first method uses the shutdown pin (only ZXSC410 and

ZXSC440). By injecting a PWM waveform on this pin and varying the

duty cycle, LED current and hence LED brightness can be adjusted.

To implement this method of brightness control on the ZXSC410/440,

a PWM signal with amplitude of between 0.7V and V

frequency of 120Hz or above (to eliminate LED flicker) should be

applied to the STDN pin. The LED current and hence LED brightness

is linearly proportional to the duty cycle ratio, so for brightness control

adjust duty cycle ratio as necessary. For example, a 10% duty cycle

equates to 10% of full LED brightness.

at a

CC

30

(A)

20

10

4 White LEDs
V = V = 3.3V

IN EN

ZXSC410/ZXSC420/ZXSC440

0

DUTY CYCLE (%)

LED Current vs. Duty Cycle

Dimming Control Using a DC Voltage

For applications where a PWM signal is not available or for the ZXSC420 a DC voltage can be used to control dimming by modulating the VFB
pin.

By adding resistors R2 and R3 and applying a DC voltage, the LED

current can be adjusted from 100% to 0%. As the DC voltage

increases, the voltage drop across R2 increases and the voltage drop

across R1 decreases, thus reducing the current through the LEDs.

Selection of R2 and R3 should ensure that the current from the DC

voltage is much less than the LED current and much larger than the

feedback current. The component values in the diagram above

represent 0% to 100% dimming control from a 0 to 2V DC voltage.

V

DC

V

R3

67k

FB

40

R2

10k

20 0100 80 60

R1

Dimming Control Using a Filtered PWM Signal

The filtered PWM signal can be considered as an adjustable

DC voltage by applying a RC filter (R4 and C1). The values

shown in the diagram below are configured to give 0% to

100% dimming for a 1kHz to 100kHz PWM signal with a 2V

amplitude. e.g. a 50% duty cycle will give 50% dimming.

R4

R3

V

FB

R2

PWM

10k

C1

67k

10k

R1

0.1µF

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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ZXSC410/ZXSC420/ZXSC440

Application Information (cont.)

Dimming Control using a Logic Signal

For applications where the LED current needs to be adjusted in

discrete steps a logic signal can be applied as shown in the diagram

below.

When Q1 is ‘off’, R1 sets the minimum LED current. When Q1 is ‘on’,

R2 sets the LED current that will be added to the minimum LED

current. The formula for selecting values for R1 and R2 are given

below:

MOSFET ‘off’

V

FB



MOSFET ‘on’

I

I

)MIN(LED

I

R

1

V

FB

I

)MAX(LED



R

2

)MIN(LED

LOGIC
SIGNAL

Q1
2N7002

R2

V

FB

R1

Layout Issues

Layout is critical for the circuit to function in the most efficient manner in terms of electrical efficiency, thermal considerations and noise.

For ‘step-up converters’ there are four main current loops, the input loop, power-switch loop, rectifier loop and output loop. The supply charging

the input capacitor forms the input loop. The power-switch loop is defined when Q1 is ‘on’, current flows from the input through the inductor, Q1,

and to ground. When Q1 is ‘off’, the energy stored in the inductor is transferred to the output capacitor and load via D1, forming the

R

SENSE

rectifier loop. The output loop is formed by the output capacitor supplying the load when Q1 is switched back off.

To optimise for best performance each of these loops kept separate from each other and interconnected with short, thick traces thus minimising

parasitic inductance, capacitance and resistance. Also the R

lead of Q1 and ground, again minimizing stray parasitics.

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

resistor should be connected, with minimum trace length, between emitter

SENSE

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F

FIC

C

Y

F

FICIENCY

Application Examples

ZXSC410 DC-DC Boost Voltage Regulators

VIN = 2.5V to 4.2V, V

OUT

= 5V; I

V

IN

= 100mA

LOAD

= 2.5V to 4.2V

ZXSC410/ZXSC420/ZXSC440

22µH

ZHCS2000

ZXTN25012EFH

22µF

22µF

100

90

(%)

IEN

E

80

70

020406080100

V = 3.6V

IN

V = 3V

IN

LOAD CURRENT (mA)

Load Current vs. Efficiency

ZXSC410

V = 4.2V

IN

R3

16k

100m 1k

100

I = 10mA

90

(%)

E

80

70

2.5 3.0 3.5 4.0

LOAD

I = 60mA

LOAD

INPUT VOLTAGE (V)

Input Voltage vs. Efficiency

C3
100nF



I = 100mA

LOAD

Switching Waveform

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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Output Ripple

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Application Examples (cont.)

Triple Output TFT Bias Generator

V

IN

4.2V ~ 3V

C1

10µF

L1

22µH

U1

V

V

CC

DRIVE

STDN

I

SENSE

GND

V

ZXSC410

Q1 ZXTN
25012EFH

FB

22m

R1

C7

1µF
C3

1µF

D1

BAT54

BAT54S

R2
30k

R3
1k

ZXSC410/ZXSC420/ZXSC440

V

ON

BAT54S

C4
1µF

C2
47µF

C8
1µF

27V, 10mA

A

VDD

9V, 180mA

ZXSC410 as Triple Output TFT Bias

Sequencing A

By adding the circuit below to the LCD bias output (VON) of

the converter a 10ms delay can be achieved between A

power up and V

in turning the PMOS transistor on, which transfers to a 10ms

delay between input and output of the circuit.

The delay is set by the RC time constant of R1 and C1. The

diode, D1, discharges the gate of the PMOS when the main

system supply is turned off, guaranteeing a delay every turn

on cycle.

and VON

VDD

power up. The circuit operates by a delay

ON

VDD

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

C5

1µF

LCD Bias
Voltage
V

ON

System
Voltage
A

VDD

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BAT54S

C6
1µF

Q1

ZXMP3A13F

C1

0.1µF

R1
470k

V

OFF

-9V, 10mA

Sequenced Output

10ms Delay

March 2013

© Diodes Incorporated

F

F

C

C

Y

OUT

P

U

T

C

U

R

R

T

ZXSC410/ZXSC420/ZXSC440

Application Examples (cont.)

Battery Powered Two 1W LED Lamp

This application shows the ZXSC410/420/440 driving 2 serial LEDs. The input voltage ranges from 2V to 3.6V with a maximum output current of

360mA from 2.6V input.

The wide input voltage range allows the use of different battery cell combinations. This could be dual alkaline cells with voltage starting from 3V

down to 2V or triple NiCad/NiMH cells with voltage starting from 3.6V down to 2.7V.

22µH

ZHCS2000

ZXTN25012EFH

100µF

22µF

ZXSC410

18m 820m 

100

90

(%)

80

IEN
I

70

E

60

50

INPUT VOLTAGE (V)

Efficiency vs. Input Voltage

2.8 2.6 2.4 2.2 2.03.6 3.4 3.2 3.0

0.4

(A)

EN

0.2

0.0

INPUT VOLTAGE (V)

LED Current vs. Input Voltage

2.8 2.6 2.4 2.2 2.03.6 3.4 3.2 3.0

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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Application Examples (cont.)

High Current LED Photoflash

The input voltage is 3V with a maximum pulsed output current of 1A for 2ms.

L1

12µH

SW1

U1

V

VBATT

C1
1µF

V

DRIVE

CC

I

STDN

SENSE

GND

V

FB

ZXSC410

C3

1µF

D1 BAT54

Q1
ZXTN
25012
EFH

R3
22m

ZXSC410/ZXSC420/ZXSC440

SW2

C2

150µF

R4
100m

Charging mode: SW1 closed, SW2 open
Discharging mode: SW1 open, SW2 closed

R1
10k 

Operation

In charging mode, SW1 is closed and SW2 is open the ZXSC410/420/440 is configured as a typical boost converter, charging capacitor C2 up

the regulated output voltage set by the ratio of R1 and R2. This is typically 16V. The peak current of the converter (current drawn from the

battery) is controlled by R3 plus R4, and is typically 280mA for this application. When C2 is charged to 16V the SW1 is opened and SW2 is

closed, converting the ZXSC400 to a step down converter to provide a 1A constant current for 2ms to the photoflash LED. During step down

operation, current flows from C2, through the photoflash LED, L1, U2 and is returned to C2 through R3. This means that the peak current is set

at a higher value than in charging mode, typically 1A. When the current reaches its peak value, U2 is switched off and current flows from L1

through the Schottky diode in U2, to the photoflash LED. This cyclic process is repeated until C2 is discharged.

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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ZXSC410/ZXSC420/ZXSC440

Ordering Information

Device Part Mark Package Code Packaging

ZXSC410E6TA C410 E6 SOT26 3000 TA

ZXSC420E6TA C420 E6 SOT26 3000 TA

ZXSC440X8TA

ZXSC

440

X8 MSOP-8EP 1000 TA

Quantity Part Number Suffix

7” Tape & Reel

Package Outline Dimensions (All dimensions in mm.)

Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version.

SOT26

MSOP-8

K

J

A

Dim Min Max Typ

B C

H

M

D

L

SOT26

A 0.35 0.50 0.38
B 1.50 1.70 1.60
C 2.70 3.00 2.80
D

 

H 2.90 3.10 3.00

J 0.013 0.10 0.05

K 1.00 1.30 1.10

L 0.35 0.55 0.40

M 0.10 0.20 0.15

0° 8°



All Dimensions in mm

0.95



y

A2

A1

D

4

x

1

0

x

1

0

°

Detail C

°

a

L

c

See Detail C

0.25

E

x

1

b

e

Gauge Plane

Seating Plane

4

E3

A3

A

E1

MSOP-8

Dim Min Max Typ

A - 1.10 ­A1 0.05 0.15 0.10
A2 0.75 0.95 0.86
A3 0.29 0.49 0.39

b 0.22 0.38 0.30

c 0.08 0.23 0.15

D 2.90 3.10 3.00

E 4.70 5.10 4.90
E1 2.90 3.10 3.00
E3 2.85 3.05 2.95

e - - 0.65

L 0.40 0.80 0.60

a 0° 8° 4°

x - - 0.750

y - - 0.750

All Dimensions in mm

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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Suggested Pad Layout

Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version.

SOT26

MSOP-8

Z

Y1

G

Y

X

X C

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

C2

C2

Dimensions Value (in mm)

Z

G

C1

Y

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X
Y

C1 2.40

C2

Dimensions Value (in mm)

ZXSC410/ZXSC420/ZXSC440

3.20

1.60

0.55

0.80

0.95

C 0.650

X 0.450
Y 1.350

Y1 5.300

© Diodes Incorporated

March 2013

ZXSC410/ZXSC420/ZXSC440

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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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Copyright © 2013, Diodes Incorporated

www.diodes.com

IMPORTANT NOTICE

LIFE SUPPORT

ZXSC410/ZXSC420/ZXSC440

Document number: DS33618 Rev. 5 - 2

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