ZXLD1350Q_技术文档

ZXLD1350Q

AUTOMOTIVE COMPLIANT 350mA BUCK LED DRIVER

Description

Pin Assignments

The ZXLD1350Q is a hysteretic mode inductive step-down converter

with integrated switch and high side current sense.

(Top View)

It operates from an input supply from 7V to 30V driving single or

multiple series connected LEDs efficiently external adjustable output

current up to 350mA.

The output current can be adjusted by applying a DC voltage or a

PWM waveform. 100:1 adjustment of output current is possible using

PWM control. Applying a voltage of 0.2V or lower to the ADJ pin turns

the output off and switches the device into a low current standby

state.

TSOT25

The ZXLD1350Q has been qualified to AEC-Q100 grade 2 and is

Automotive Compliant supporting PPAPs.

Features



Simple Low Parts Count

Internal 30V NDMOS Switch

Internal PWM Filter

High Efficiency (Up to 95%)

Wide Input Voltage Range: 7V to 30V

40V Transient Capability

Up to 1MHz Switching Frequency

Typical 4% Output Current Accuracy

Green Molding (No Br, Sb) in TSOT25

Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)

Halogen and Antimony Free. “Green” Device (Note 3)

Automotive Compliant

Qualified to AEC-Q100 Standards for High Reliability

PPAP Capable (Note 4)

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/quality/lead_free.html 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.

4. Automotive products are AEC-Q100 qualified and are PPAP capable. Refer to https://www.diodes.com/quality/product-compliance-definitions/.

Typical Application Circuit

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ZXLD1350Q

Block Diagram

R_S

V_IN

L1

D1

V

IN

I_SENSE

LX

V

IN

R1

Current sense circuit

Voltage

regulator

5V

-

+

Shutdown

circuit

C1

Comparator

-

MN

+

ADJ

R2

4KHz

200k

Vref

1.25V

R3

GND

Block Diagram – Pin Connection

Pin Description

Pin Number

Pin Name

Description

1

2

LX

Drain of NDMOS switch

GND

Ground (0V)

Multi-function On/Off and brightness control pin:



Leave floating for normal operation

.

V_ADJ= V_REF= 1.25V  giving nominal average output current  I_OUTnom= 0.1/R_S



Drive to voltage below 0.2V to turn off output current.

Drive with Analog voltage:

3

ADJ

.

0.3V < V_ADJ< 2.5V  adjusts output current from 25% to 200%^(†)of I_OUTnom



Drive with PWM signal from open-collector or open-drain transistor, to adjust output current.

.

Adjustment range 25% to 100% of I_OUTnomfor f > 10kHz and 1% to 100% of I_OUTnomfor f < 500Hz

Connect a capacitor from this pin to ground to increase soft-start time. (Default soft-start time = 0.5ms.

.

Additional soft-start time is approx.0.5ms/nF)

Connect resistor R_Sfrom this pin to V_INto define nominal average output current I_OUTnom= 0.1/R_S

(Note: R_SMIN= 0.27Ω with ADJ pin open circuit)

4

5

I_SENSE

V_IN

Input voltage (7V to 30V). Decouple to ground with 1µF of higher X7R ceramic capacitor close to device

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Absolute Maximum Ratings (Voltages to GND Unless Otherwise Stated)

Symbol

Parameter

Rating

-0.3 to +30

Unit

V_IN

Input Voltage

V

(40V for 0.5 sec)

+0.3 to -5

V_SENSE

I_SENSEVoltage

LX Output Voltage

V

(measured with respect to V_IN)

-0.3 to +30

V_LX

V

(40V for 0.5 sec)

-0.3 to +6

V_ADJ

I_LX

Adjust Pin Input Voltage

Switch Output Current

Power Dissipation

V

500

mA

P_TOT

450

mW

(Refer to Package Thermal De-rating Curve on Page 17)

Storage Temperature

T_ST

-55 to +150

+150

° C

T_{J MAX}

Junction Temperature

ESD Susceptibility

HBM

CDM

MM

Human Body Model

500

1000

75

V

Charged Device Model

Machine Model

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 conditions between maximum recommended operating conditions and absolute maximum ratings 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.)

Thermal Resistance

Symbol

Parameter

Rating

Unit

_JA

Junction to Ambient

200

°C/W

Recommended Operating Conditions

Symbol

V_IN

Parameter

Min

7

Typ.

—

Max

30

Units

V

Input Voltage

t_OFFMIN

t_ONMIN

D_LX

Minimum Switch Off-time

—

800

0.99

+105

0.37

1

ns

Minimum Switch On-time

—

ns

Duty Cycle Range

0.01

-40

—

T_A

Ambient Operating Temperature Range

Average/RMS LX Switch Current

Recommended Maximum Operating Frequency

Internal Comparator Propagation Delay

—

° C

I_{LX_CONT}

f_LXmax

t_PD

—

A

—

MHz

ns

—

50

—

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Electrical Characteristics (Test conditions: V_IN= 12V, T_amb= +25°C, unless otherwise specified.)

Symbol

V_SU

Parameter

Condition

Min.

—

Typ.

4.8

Max.

—

Unit

V

Internal Regulator Start-up Threshold

Quiescent Supply Current with Output Off

Quiescent Supply Current with Output Switching

V_INrising

I_INQoff

I_INQon

ADJ pin grounded

—

15

20

µ A

ADJ pin floating, f = 250kHz

—

250

500

Measured on I_SENSEpin with

respect to V_IN

Mean Current Sense Threshold Voltage

(Defines LED Current Setting Accuracy)

V_SENSE

95

100

105

mV

V_ADJ= 1.25V

V_SENSEHYSSense Threshold Hysteresis

—

15

—

%

I_SENSE

I_SENSEPin Input Current

V_SENSE= V_IN-0.1

1.25

10

µ A

Measured on ADJ pin with pin

floating

V_REF

Internal Reference Voltage

1.21

—

1.25

50

1.29

—

V

ppm/°C

V

V_REF/T Temperature Coefficient of V_REF

—

External Control Voltage Range on ADJ Pin for DC

V_ADJ

—

0.3

—

2.5

Brightness Control (Note 5)

DC Voltage on ADJ Pin to Switch Device from Active

(On) State to Quiescent (Off) State

V_ADJoff

V_ADJfalling

V_ADJrising

0.15

0.2

0.25

0.3

V

DC Voltage on ADJ Pin to Switch Device from

Quiescent (Off) State to Active (On) State

V_ADJon

0.25

R_ADJ

I_LXmean

R_LX

Resistance between ADJ Pin and V_REF

Continuous LX Switch Current

LX Switch ‗On‘ Resistance

—

135

—

250

0.37

2

kΩ

A

—

1.5

—

Ω

I_LX(leak)

LX Switch Leakage Current

—

1

µ A

Duty Cycle Range of PWM Signal Applied to ADJ Pin

during Low Frequency PWM Dimming Mode

PWM frequency <500Hz PWM

amplitude = V_REF

0.01

—

100:1

—

1

—

1

—

D_PWM(LF)

Measured on ADJ pin

Brightness Control Range

Duty Cycle Range of PWM Signal Applied to ADJ Pin

during High Frequency PWM Dimming Mode

PWM frequency <10kHz PWM

amplitude = V_REF

0.16

—

D_PWM(HF)

Measured on ADJ pin

ADJ pin floating

Brightness Control Range

5:1

—

Operating Frequency

L = 100H (0.82V)

f_LX

—

250

500

—

kHz

µ s

(See Graphs for More Details)

I_OUT= 350mA @ V_LED= 3.4V

Driving 1 LED

Time taken for output current to

reach 90% of final value after

voltage on ADJ pin has risen

above 0.3V.

Start Up Time

t_SS

(See Graphs for More Details)

Note:

5. 100% brightness corresponds to V_ADJ= V_ADJ(nom)= V_REF. Driving the ADJ pin above V_REFwill increase the V_SENSEthreshold and output current

proportionally.

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ZXLD1350Q

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Device Description

The device, in conjunction with the coil (L1) and current sense resistor (R_S), forms a self-oscillating continuous-mode buck converter.

Device Operation (Refer to block diagram and Figure 1 - Operating waveforms)

t_OFF

t_ON

Figure 1. Theoretical Operating Waveforms

Operation can be best understood by assuming that the ADJ pin of the device is unconnected and the voltage on this pin (V_ADJ) appears directly at

the (+) input of the comparator.

When input voltage V_INis first applied, the initial current in L1 and R_Sis zero and there is no output from the current sense circuit. Under this

condition, the (-) input to the comparator is at ground and its output is high. This turns MN on and switches the LX pin low, causing current to flow

from V_INto ground, via R_S, L1 and the LED(s). The current rises at a rate determined by V_INand L1 to produce a voltage ramp (V_SENSE) across R_S.

The supply referred voltage V_SENSEis forced across internal resistor R1 by the current sense circuit and produces a proportional current in internal

resistors R2 and R3. This produces a ground referred rising voltage at the (-) input of the comparator. When this reaches the threshold voltage

(V_ADJ), the comparator output switches low and MN turns off. The comparator output also drives another NMOS switch, which bypasses internal

resistor R3 to provide a controlled amount of hysteresis. The hysteresis is set by R3 to be nominally 15% of V_ADJ.

When MN is off, the current in L1 continues to flow via D1 and the LED(s) back to V_IN. The current decays at a rate determined by the LED and

diode forward voltages to produce a falling voltage at the input of the comparator. When this voltage returns to V_ADJ, the comparator output

switches high again. This cycle of events repeats, with the comparator input ramping between limits of V_ADJ15%.

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Device Description (Cont.)

Switching Thresholds

With V_ADJ= V_REF, the ratios of R1, R2 and R3, define an average V_SENSEswitching threshold of 100mV (measured on the I_SENSEpin with respect

to V_IN). The average output current I_OUTnomis then defined by this voltage and R_Saccording to:

I_OUTnom= 100mV/R_S

Nominal ripple current is 15mV/R_S.

Adjusting Output Current

The device contains a low pass filter between the ADJ pin and the threshold comparator and an internal current limiting resistor (200k nom)

between ADJ and the internal reference voltage. This allows the ADJ pin to be overdriven with either DC or pulse signals to change the V_SENSE

switching threshold and adjust the output current. The filter is third order, comprising three sections, each with a cut-off frequency of nominally

4kHz.

Details of the different modes of adjusting output current are given in the applications section.

Output Shutdown

The output of the low pass filter drives the shutdown circuit. When the input voltage to this circuit falls below the threshold (0.2V nom), the internal

regulator and the output switch are turned off. The voltage reference remains powered during shutdown to provide the bias current for the

shutdown circuit. Quiescent supply current during shutdown is nominally 15mA and switch leakage is below 1mA.

Typical Operating Waveforms [V_IN= 12V, R_S= 0.3, L = 100μH]

Normal Operation. Output Current (Ch3) and LX Voltage (Ch1)

Start-up Waveforms. Output Current (Ch3), LX Voltage (Ch1) and

V_ADJ(Ch2)

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Typical Operating Conditions

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Typical Characteristics (Cont.)

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Typical Characteristics (Cont.)

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Application Information

Setting Nominal Average Output Current with External Resistor R_S

The nominal average output current in the LED(s) is determined by the value of the external current sense resistor (R_S) connected between V_IN

and I_SENSEand is given by:

I_OUTnom= 0.1/R_S[for R_S 0.27Ω]

The table below gives values of nominal average output current for several preferred values of current setting resistor (R_S) in the typical

application circuit shown on page 1:

R_S(Ω)

0.27

0.30

0.33

0.39

Nominal Average Output Current (mA)

370

333

300

256

The above values assume that the ADJ pin is floating and at a nominal voltage of V_REF(=1.25V). Note that R_S= 0.27 is the minimum allowed

value of sense resistor under these conditions to maintain switch current below the specified maximum value.

It is possible to use different values of R_Sif the ADJ pin is driven from an external voltage. (See next section).

Output Current Adjustment by External DC Control Voltage

The ADJ pin can be driven by an external dc voltage (V_ADJ), as shown, to adjust the output current to a value above or below the nominal average

value defined by R_S.

ZXLD1350Q

ZXLD1350

ADJ

+

GND

DC

GND

The nominal average output current in this case is given by:

I_OUTdc= 0.08*V_ADJ/R_S

for 0.3 < V_ADJ< 2.5V

Note that 100% brightness setting corresponds to V_ADJ= V_REF. When driving the ADJ pin above 1.25V, R_Smust be increased in proportion to

prevent I_OUTdcexceeding 370mA maximum.

The input impedance of the ADJ pin is 200kΩ ±25%.

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Application Information (Cont.)

Output Current Adjustment by PWM Control

Directly Driving ADJ Input

A Pulse Width Modulated (PWM) signal with duty cycle D_PWMcan be applied to the ADJ pin, as shown below, to adjust the output current to a

value above or below the nominal average value set by resistor R_S:

PWM

V_ADJ

ZXLD1350

ZXLD1350Q

ADJ

GND

0V

GND

Driving the ADJ Input via Open Collector Transistor

The recommended method of driving the ADJ pin and controlling the amplitude of the PWM waveform is to use a small NPN switching transistor

as shown below:

ADJ

ZXLD1350

ZXLD1350Q

PWM

GND

This scheme uses the 200k resistor between the ADJ pin and the internal voltage reference as a pull-up resistor for the external transistor.

Driving the ADJ Input from a Microcontroller

Another possibility is to drive the device from the open drain output of a microcontroller. The diagram below shows one method of doing this:

MCU

10k

ZXLD1350

ZXLD1350Q

ADJ

GND

The diode and resistor suppress possible high amplitude negative spikes on the ADJ input resulting from the drain-source capacitance of the FET.

Negative spikes at the input to the device should be avoided as they may cause errors in output current, or erratic device operation.

PWM dimming can be further split into high frequency and low frequency PWM dimming and how the device responds to these.

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Application Information (Cont.)

Low Frequency PWM Mode

When the ADJ pin is driven with a low frequency PWM signal (eg 100Hz), with a high level voltage V

and a low level of zero, the output of the

ADJ

internal low pass filter will swing between 0V and V

, causing the input to the shutdown circuit to fall below its turn-off threshold (200mV nom)

ADJ

when the ADJ pin is low. This will cause the output current to be switched on and off at the PWM frequency, resulting in an average output current

proportional to the PWM duty cycle. (See Figure 2 - Low frequency PWM operating waveforms).

I

OUTavg

t_ON

t_OFF

Figure 2. Low frequency PWM operating waveforms

Figure 2. Low Frequency PWM Operating Waveforms

The average value of output current in this mode is given by:

I_OUTavg= 0.1D_PWM/R_Sfor D_PWM>0. 01

This mode is preferable if optimum LED 'whiteness' is required. It will also provide the widest possible dimming range (approx. 100:1) and higher

efficiency at the expense of greater output ripple.

Note that the low pass filter introduces a small error in the output duty cycle due to the difference between the start-up and shut-down time. This

time difference is a result of the 200mV shutdown threshold and the rise and fall times at the output of the filter. To minimize this error, the PWM

duty cycle should be as low as possible consistent with avoiding flicker in the LED.

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Application Information (Cont.)

High Frequency PWM Mode

At PWM frequencies above 10kHz and for duty cycles above 0.16, the output of the internal low pass filter will contain a DC component that is

always above the shutdown threshold. This will maintain continuous device operation and the nominal average output current will be proportional

to the average voltage at the output of the filter, which is directly proportional to the duty cycle. (See Figure 3 – High frequency PWM operating

waveforms). For best results, the PWM frequency should be maintained above the minimum specified value of 10kHz, in order to minimize ripple

at the output of the filter. The shutdown comparator has approximately 50mV of hysteresis, to minimize erratic switching due to this ripple. An

upper PWM frequency limit of approximately one tenth of the operating frequency is recommended, to avoid excessive output modulation and to

avoid injecting excessive noise into the internal reference.

t_ON

t_OFF

Figure 3. High Frequency PWM Operating Waveforms

The nominal average value of output current in this mode is given by:

I_OUTnom»0.1D_PWM/R_Sfor D_PWM> 0.16

This mode will give minimum output ripple and reduced radiated emission, but with a reduced dimming range (approx.5:1). The restricted dimming

range is a result of the device being turned off when the DC component on the filter output falls below 200mV.

Shutdown Mode

Taking the ADJ pin to a voltage below 0.2V for more than approximately 100μs, will turn off the output and supply current will fall to a low standby

level of 15μA nominal.

Note that the ADJ pin is not a logic input. Taking the ADJ pin to a voltage above V

average value. (See graphs for details).

will increase output current above the 100% nominal

REF

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Application Information (Cont.)

Soft-start

The device has inbuilt soft-start action due to the delay through the PWM filter. An external capacitor from the ADJ pin to ground will provide

additional soft-start delay, by increasing the time taken for the voltage on this pin to rise to the turn-on threshold and by slowing down the rate of

rise of the control voltage at the input of the comparator. With no external capacitor, the time taken for the output to reach 90% of its final value is

approximately 500μs. Adding capacitance increases this delay by approximately 0.5ms/nF.

The graph below shows the variation of soft-start time for different values of capacitor.

Inherent Open-circuit LED Protection

If the connection to the LED(s) is open-circuited, the coil is isolated from the LX pin of the chip, so the device will not be damaged, unlike in many

boost converters, where the back EMF may damage the internal switch by forcing the drain above its breakdown voltage.

Capacitor Selection

A low ESR capacitor should be used for input decoupling, as the ESR of this capacitor appears in series with the supply source impedance and

lowers overall efficiency. This capacitor has to supply the relatively high peak current to the coil and smooth the current ripple on the input supply.

A minimum value of 1μF is acceptable if the input source is close to the device, but higher values will improve performance at lower input voltages,

especially when the source impedance is high. The input capacitor should be placed as close as possible to the IC.

For maximum stability over temperature and voltage, capacitors with X7R, X5R, or better dielectric are recommended. Capacitors with Y5V

dielectric are not suitable for decoupling in this application and should NOT be used.

A table of recommended manufacturers is provided below:

Manufacturer

Murata

Website

www.murata.com

www.t-yuden.com

www.kemet.com

www.avxcorp.com

Taiyo Yuden

Kemet

AVX

Inductor Selection

Recommended inductor values for the ZXLD1350Q are in the range 47µH to 220µH.

Higher values of inductance are recommended at higher supply voltages in order to minimize errors due to switching delays, which result in

increased ripple and lower efficiency. Higher values of inductance also result in a smaller change in output current over the supply voltage range.

(See graphs). The inductor should be mounted as close to the device as possible with low resistance connections to the LX and V pins.

IN

The chosen coil should have a saturation current higher than the peak output current and a continuous current rating above the required mean

output current.

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Application Information (Cont.)

Suitable coils for use with the ZXLD1350Q are listed in the table below:

I_SAT(A)

0.5

Part Number

L (µH)

47

DCR (V)

0.64

Manufacturer

DO1608C

47

0.38

0.56

0.47

0.39

0.53

0.38

CoilCraft

MSS6132ML

68

0.58

100

220

47

0.82

CD104-MC

0.55

Sumida

NP04SB470M

0.27

Taiyo Yuden

The inductor value should be chosen to maintain operating duty cycle and switch 'on'/'off' time within the specified limits over the supply voltage

and load current range.

The following equations can be used as a guide, with reference to Figure 1 - Operating waveforms.

LX Switch 'On' Time

LI

t_ON



V

_IN V_LEDI_avg



R_Sr_LR_LX



Note: t

ONnmin

> 200ns

LX Switch 'Off' Time

LI

t_OFF



V_LED V_DI_avg



R_Sr_L



Note: t

> 200ns

OFFmin

Where:

L is the coil inductance (H)

r_Lis the coil resistance ()

I

is the required LED current (A)

avg

I is the coil peak-peak ripple current (A) {Internally set to 0.3 x I_avg

}

V

is the supply voltage (V)

IN

is the total LED forward voltage (V)

LED

R

LX

is the switch resistance ()

V

is the rectifier diode forward voltage at the required load current (V)

D

Example:

For V_IN= 12V, L = 47µH, r_L= 0.64, V

= 3.4V, I_avg= 350mA and V_D= 0.36V

LED

t_ON= (47e-6 x 0.105)/(12 - 3.4 - 0.672) = 0.622µs

t_OFF= (47e-6 x 0.105)/(3.4 + 0.36 + 0.322) = 1.21µs

This gives an operating frequency of 546kHz and a duty cycle of 0.34.

These and other equations are available as a spreadsheet calculator from the Diodes website.

Note that in practice, the duty cycle and operating frequency will deviate from the calculated values due to dynamic switching delays, switch

rise/fall times and losses in the external components.

Optimum performance will be achieved by setting the duty cycle close to 0.5 at the nominal supply voltage. This helps to equalize the undershoot

and overshoot and improves temperature stability of the output current.

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Application Information (Cont.)

Diode Selection

For maximum efficiency and performance, the rectifier (D1) should be a fast low capacitance Schottky diode with low reverse leakage at the

maximum operating voltage and temperature. The recommended diode for use with this part is the DFLS140Q. This has approximately ten times

lower leakage than standard Schottky diodes, which are unsuitable for use above +85°C. It also provides better efficiency than silicon diodes, due

to a combination of lower forward voltage and reduced recovery time.

The table below gives the typical characteristics for the DFLS140Q:

Continuous

Current

(mA)

Reverse Leakage

@ 30V +85°C

(µA)

Forward Voltage @

300mA (mV)

Diode

Package

®

PowerDI 123

DFLS140Q

410

1000

100

If alternative diodes are used, it is important to select parts with a peak current rating above the peak coil current and a continuous current rating

higher than the maximum output load current. It is very important to consider the reverse leakage of the diode when operating above +85°C.

Excess leakage will increase the power dissipation in the device.

The higher forward voltage and overshoot due to reverse recovery time in silicon diodes will increase the peak voltage on the LX output. If a silicon

diode is used, care should be taken to ensure that the total voltage appearing on the LX pin including supply ripple, does not exceed the specified

maximum value.

Reducing Output Ripple

Peak to peak ripple current in the LED(s) can be reduced, if required, by shunting a capacitor Cled across the LED(s) as shown below:

R_S

V_IN

LED

L1

Cled

D1

V_IN

I_SENSE

LX

ZXLD1350

ZXLD1350Q

A value of 1μF will reduce nominal ripple current by a factor three (approx.). Proportionally lower ripple can be achieved with higher capacitor

values. Note that the capacitor will not affect operating frequency or efficiency, but it will increase start-up delay, by reducing the rate of rise of

LED voltage.

Operation at low supply voltage

The internal regulator disables the drive to the switch until the supply has risen above the start-up threshold (VSU). Above this threshold, the

device will start to operate. However, with the supply voltage below the specified minimum value, the switch duty cycle will be high and the device

power dissipation will be at a maximum. Care should be taken to avoid operating the device under such conditions in the application, in order to

minimize the risk of exceeding the maximum allowed die temperature. (See next section on thermal considerations).

Note that when driving loads of two or more LEDs, the forward drop will normally be sufficient to prevent the device from switching below

approximately 6V. This will minimize the risk of damage to the device.

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Application Information (Cont.)

Thermal Considerations

When operating the device at high ambient temperatures, or when driving maximum load current, care must be taken to avoid exceeding the

package power dissipation limits. The graph below gives details for power derating. This assumes the device to be mounted on a (25mm)²PCB

with 1oz copper standing in still air.

Note that the device power dissipation will most often be a maximum at minimum supply voltage. It will also increase if the efficiency of the circuit

is low. This may result from the use of unsuitable coils, or excessive parasitic output capacitance on the switch output.

Thermal Compensation of Output Current

High luminance LEDs often need to be supplied with a temperature compensated current in order to maintain stable and reliable operation at all

drive levels. The LEDs are usually mounted remotely from the device, so for this reason, the temperature coefficients of the internal circuits for the

ZXLD1350Q have been optimized to minimize the change in output current when no compensation is employed. If output current compensation is

required, it is possible to use an external temperature sensing network - normally using Negative Temperature Coefficient (NTC) thermistors

and/or diodes, mounted very close to the LED(s). The output of the sensing network can be used to drive the ADJ pin in order to reduce output

current with increasing temperature.

Layout Considerations

LX Pin

The LX pin of the device is a fast switching node, so PCB tracks should be kept as short as possible. To minimize ground 'bounce', the ground pin

of the device should be soldered directly to the ground plane.

Coil and Decoupling Capacitors

It is particularly important to mount the coil and the input decoupling capacitor close to the device to minimize parasitic resistance and inductance,

which will degrade efficiency. It is also important to take account of any track resistance in series with current sense resistor R_S.

ADJ Pin

The ADJ pin is a high impedance input, so when left floating, PCB tracks to this pin should be as short as possible to reduce noise pickup. A

100nF capacitor from the ADJ pin to ground will reduce frequency modulation of the output under these conditions. An additional series 10kΩ

resistor can also be used when driving the ADJ pin from an external circuit (see below). This resistor will provide filtering for low frequency noise

and provide protection against high voltage transients.

10k

ZXLD1350Q

ZXLD1350

GND

ADJ

100nF

GND

High Voltage Tracks

Avoid running any high voltage tracks close to the ADJ pin, to reduce the risk of leakage due to board contamination. Any such leakage may raise

the ADJ pin voltage and cause excessive output current. A ground ring placed around the ADJ pin will minimize changes in output current under

these conditions.

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Document number: DS37076 Rev. 2 - 2

ZXLD1350Q

Ordering Information

Q : Automotive

Compliant

Packing: 7” Tape and Reel

Package Part

(Note 6) Mark

Package

Qualification Grade

(Note 7)

Device

Code

Quantity Per Reel Tape Width Part Number Suffix

ZXLD1350QET5TA

ET5

TSOT25 1350

3000

8mm

TA

Automotive Compliant

Note:

6. Pad layout as shown in Diodes Incorporated‘s package outline PDFs, which can be found on our website at http://www.diodes.com/package-outlines.html.

7. ZXLD1350Q has been qualified to AEC-Q100 grade 2 and is classified as ―Automotive Compliant‖ supporting PPAP documentation.

See ZXLD1350 datasheet for commercial qualified versions.

Marking Information

TSOT25

XXXX : Identification Code : 1350

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Package Outline Dimensions

Please see http://www.diodes.com/package-outlines.html for the latest version.

TSOT25

D

e1

TSOT25

Min Max

1.00

01( 4x)

Dim

A

Typ

-

E1/2

A1

A2

b

c

D

E

E1

e

e1

L

L2

θ

0.01 0.10

0.84 0.90

0.30 0.45

0.12 0.20

E/2

c

E1

E

-

Gauge Plane

Seating Plane

-

2.90

2.80

1.60

0

L

L2

0.95 BSC

1.90 BSC

01( 4x)

e

b

A2

0.30 0.50

0.25 BSC

8°

12°

A1

0°

4°

-

A

θ1

Seating Plane

All Dimensions in mm

Suggested Pad Layout

Please see http://www.diodes.com/package-outlines.html for the latest version.

TSOT25

C

Dimensions Value (in mm)

C

X

Y

0.950

0.700

1.000

3.199

Y1

Y

X

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Document number: DS37076 Rev. 2 - 2

ZXLD1350Q

Revision History

Date

December

2014

Revision

1-2

Changes

Initial release

Added further clarification of Automotive Compliance and reference to Diodes’ definition (Page 1, Note

4 and page 18, Note 7)

Corrected device part mark to include pin 1 identifier (Pages 1 and 18)

Correction of ESD ratings (Page 3) (Note 8):

Incorrect revision 1-2

specification

Corrected revision 2-2

specification

January 2017

2-2

ESD Rating

Unit

HBM

MM

Human Body Model

500

100

500

75

V

Machine Model

CDM

Charged Device Model

1000

Note 8. The actual physical ESD withstand capability is unaltered.

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Document number: DS37076 Rev. 2 - 2

ZXLD1350Q

IMPORTANT NOTICE

DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT,

INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

(AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).

Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes

without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the

application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or

trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume

all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated

website, harmless against all damages.

Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel.

Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and

hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or

indirectly, any claim of personal injury or death associated with such unintended or unauthorized application.

Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings

noted herein may also be covered by one or more United States, international or foreign trademarks.

This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the

final and determinative format released by Diodes Incorporated.

LIFE SUPPORT

Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express

written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:

A. Life support devices or systems are devices or systems which:

1. are intended to implant into the body, or

2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the

labeling can be reasonably expected to result in significant injury to the user.

B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the

failure of the life support device or to affect its safety or effectiveness.

Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and

acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any

use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related

information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its

representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems.

www.diodes.com

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ZXLD1350Q

Document number: DS37076 Rev. 2 - 2


型号：	ZXLD1350Q
厂家：	DIODES INCORPORATED
描述：	AUTOMOTIVE COMPLIANT 350mA BUCK LED DRIVER 驱动
文件：	总21页 (文件大小：767K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

ZXLD1350Q [DIODES]

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