Diodes ZXLD1370 User Manual

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Description

The ZXLD1370 is an LED driver controller IC for driving external

MOSFETs to drive high current LEDs. It is a multi-topology controller

enabling it to efficiently control the current through series connected

LEDs. The multi-topology enables it to operate in buck, boost and

buck-boost configurations.

The 60V capability coupled with its multi-topology capability enables it

to be used in a wide range of applications and drive in excess of

15 LEDs in series.

The ZXLD1370 is a modified hysteretic controller using a patent

pending control scheme providing high output current accuracy in all

three modes of operation. High accuracy dimming is achieved

through DC control and high frequency PWM control.

The ZXLD1370 uses two pins for fault diagnosis. A flag output

highlights a fault, while the multi-level status pin gives further

information on the exact fault.

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ZXLD1370

60V HIGH ACCURACY BUCK/BOOST/BUCK-BOOST

LED DRIVER-CONTROLLER WITH AEC-Q100

Pin Assignments

TSSOP-16EP

Features

• 0.5% Typical Output Current Accuracy

• 6V to 60V Operating Voltage Range

• LED Driver Supports Buck, Boost and Buck-Boost

Configurations

• Wide Dynamic Range Dimming

• 20:1 DC Dimming

• 1000:1 Dimming Range at 500Hz

• Up to 1MHz Switching

• High Temperature Control of LED Current Using TADJ

• Available in Automotive Grade with AEC-Q100 and TS16949

Certification

• Available in “Green” Molding Compound (No Br, Sb) with Lead

Free Finish/ RoHS Compliant

 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.

ZXLD1370

Document number: DS32165 Rev. 5 - 2

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Typical Applications Circuit

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ZXLD1370

Buck-Boost Diagram Utilizing Thermistor and TADJ

Functional Block Diagram

Curve Showing LED Current vs. T

LED

ZXLD1370

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Pin Descriptions

Pin Name Pin

ADJ 1 I

REF 2 O Internal 1.25V reference voltage output.

TADJ 3 I

SHP 4 I/O

STATUS 5 O

SGND 6 P Signal ground (Connect to 0V)

PGND 7 P Power ground - Connect to 0V and pin 8 to maximize copper area

N/C 8 -

N/C 9

GATE 10 O Gate drive output to external NMOS transistor – connect to pin 9

V

AUX

VIN

ISM 13 I

FLAG 14 O

PWM 15 I

GI 16 I

EP PAD P Exposed paddle. Connect to 0V plane for electrical and thermal management

Note: 4. Type refers to whether or not pin is an Input, Output, Input/Output or power supply pin.

11 P

12 P

ZXLD1370

Document number: DS32165 Rev. 5 - 2

Type

(Note 4)

Function

Adjust input (for dc output current control). Connect to REF to set 100% output current.

Drive with dc voltage (125mV<V The ADJ pin has an internal clamp that limits the internal failsafe should they get overdriven.

Temperature Adjust input for LED thermal current control. Connect thermistor/resistor network to this pin to reduce output current above a preset temperature

threshold.

Connect to REF to disable thermal compensation function. (See section on thermal control.)

Shaping capacitor for feedback control loop. Connect 100pF ±20% capacitor from this pin to ground to provide loop compensation.

Operation status output (analog output) Pin is at 4.5V (nominal) during normal operation. Pin switches to a lower voltage to indicate specific operation warnings or fault conditions. (See section on STATUS output.) Status pin voltage is low during shutdown mode.

Not Connected internally – recommend connection to pin 7, (PGND), to maximize PCB copper for

thermal dissipation

Not Connected internally – recommend connection pin 10 (GATE) to permit wide copper trace to gate

of MOSFET

Auxiliary positive supply to internal switch gate driver. Connect to V

to application section for more details) Decouple to ground with capacitor close to device (refer to Applications section)

Input supply to device (6V to 60V). Decouple to ground with capacitor close to device (refer to Applications section)

Current monitor input. Connect current sense resistor between this pin and V The nominal voltage across the resistor is 225mV

Flag open drain output. Pin is high impedance during normal operation Pin switches low to indicate a fault, or warning condition

Digital PWM output current control. Pin driven either by open Drain or push-pull 3.3V or 5V logic levels. Drive with frequency higher than 100Hz to gate output ‘on’ and ‘off’ during dimming control. The device enters standby mode when PWM pin is driven with logic low level for more than 15ms

nominal (Refer to application section for more details)

Gain setting input. Used to set the device in Buck mode or Boost, Buck-boost modes Connect to ADJ in Buck mode operation For Boost and Buck-boost modes, connect to resistive divider from ADJ to SGND. This defines the ratio

of switch current to LED current (see application section). The GI pin has an internal clamp that limits the internal

, or auxiliary supply from 6V to 15V supply to reduce internal power dissipation (Refer

IN

node to less than 3V. This provides some failsafe should they get overdriven

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< 2.5V) to adjust output current from 10% to 200% of set value.

ADJ

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node to less than 3V. This provides some

IN

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ZXLD1370

Absolute Maximum Ratings (Note 5) (Voltages to GND, unless otherwise specified.)

Symbol Parameter Rating Unit

VIN

V

AUX

V

ISM

V

SENSE

V

GATE

I

GATE

V

FLAG

V

, V

PWM

ADJ

, VGI

V

TADJ

TJ

TST

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.

Input Supply Voltage Relative to GND -0.3 to +65 V

Auxiliary Supply Voltage Relative to GND -0.3 to +65 V

Current Monitor Input Relative to GND -0.3 to +65 V

Current Monitor Sense Voltage (VIN-V

Gate Driver Output Voltage -0.3 to +20 V

ISM

)

-0.3 to +5 V

Gate Driver Continuous Output Current 18 mA

Flag Output Voltage -0.3 to 40 V

,

Other Input Pins -0.3 to +5.5 V

Maximum Junction Temperature 150 °C

Storage Temperature -55 to +150 °C

Package Thermal Data

Thermal Resistance Package Typical Unit

Junction-to-Ambient, 

(Note 6)

JA

Junction-to-Case, JC

Notes: 5. For correct operation SGND and PGND should always be connected together.

6. Measured on High Effective Thermal Conductivity Test Board" according JESD51.

ZXLD1370

Document number: DS32165 Rev. 5 - 2

TSSOP-16EP 50 °C/W

TSSOP-16EP 23 °C/W

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ZXLD1370

Recommended Operating Conditions (@T

Symbol Parameter Performance/Comment Min Max Unit

VIN

V

AUX

V

ISM

V

SENSE

V

ADJ

I

REF

f

max

V

TADJ

f

PWM

t

PWMH/L

V

PWMH

V

PWML

TJ

GI Gain setting ratio for boost and buck-boost modes

Notes: 7. Device starts up above 6V and as such the minimum applied supply voltage has to be above 6.5V (plus any noise margin). The ZXLD1370 will, however, continue to function when the input voltage is reduced from  8V down to 6.3V. When operating with input voltages below 8V the output current and device parameters may deviate from their normal values; and is dependent on power MOSFET switch, load and ambient temperature conditions. To ensure best operation in Boost and Buck-Boost modes with input voltages, V

between 6.3 and 8V a suitable boot-strap network on V Performance in Buck mode will be reduced at input voltages (V

8. V not be applied to V

9. The device contains circuitry to control the switching frequency to approximately 400kHz. The maximum and minimum operating frequency is not tested in production.

Input supply voltage range

Auxiliary supply voltage range (Note 8)

Current sense monitor input range 6.3 60 V

Differential input voltage

External dc control voltage applied to ADJ pin to adjust output current

Reference external load current REF sourcing current 1 mA

Recommended switching frequency range (Note 9)

Temperature adjustment (T

) input voltage range

ADJ

Recommended PWM dimming frequency range

PWM pulse width in dimming mode PWM input high or low 0.002 10 ms

PWM pin high level input voltage 2 5.5 V

PWM pin low level input voltage 0 0.4 V

Operating Junction Temperature Range -40 125 °C

can be driven from a voltage higher than VIN to provide higher efficiency at low VIN voltages, but to avoid false operation; a voltage should

AUX

in the absence of a voltage at VIN.

AUX

= +25°C, unless otherwise specified.)

A

Normal operation 8

Reduced performance operation (Note 7)

Normal operation 8

Reduced performance operation (Note 7)

V

VIN-VISM

, with 0  V

ADJ

DC brightness control mode from 10% to 200%

300 1000 kHz

0

To achieve 1000:1 resolution 100 500 Hz

To achieve 500:1 resolution 100 1000 Hz

Ratio = V

pin is recommended.

AUX

, V

) below 8V. – a boot-strap network cannot be implemented in buck mode.

IN

AUX

GI/VADJ

 2.5

6.3

60 V

0 450 mV

0.125 2.5 V

V

REF

V

0.20 0.50

,

IN

ZXLD1370

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Electrical Characteristics (Note 5) (V

Symbol Parameter Conditions Min Typ Max Units

Supply and Reference Parameters

V

UV-

V

UV+

I

Q-IN

I

Q-AUX

I

SB-IN

I

SB-AUX

V

REF

ΔV

REF

V

REF_LINE

V

REF-TC

DC-DC Converter Parameters

V

ADJ

I

ADJ

VGI

IGI

I

PWM

t

PWMoff

T

SDH

T

SDL

High-Side Current Monitor (Pin ISM)

I

ISM

V

SENSE

V

SENSE_acc

V

SENSE-OC

Notes: 10. The ADJ and GI pins have an internal clamp that limits the internal node to less than 3V. This provides some failsafe should those pins get overdriven.

11. Initial sense voltage in Boost and Buck-Boost modes at maximum duty cycle.

ZXLD1370

Document number: DS32165 Rev. 5 - 2

Under-Voltage detection threshold Normal operation to switch disabled

Under-Voltage detection threshold Switch disabled to normal operation

Quiescent current into VIN

Quiescent current into V

AUX

Standby current into VIN.

Standby current into V

Internal reference voltage No load 1.237 1.250 1.263 V

Change in reference voltage with output current

Reference voltage line regulation

Reference temperature coefficient +/-50 ppm/°C

External dc control voltage applied to ADJ pin to adjust output current (Note 8)

ADJ input current (Note 10)

AUX

.

GI Voltage threshold for boost and buck-boost modes selection (Note 8)

GI input current (Note 10)

PWM input current

PWM pulse width (to enter shutdown state)

Thermal shutdown upper threshold (GATE output forced low)

Thermal shutdown lower threshold (GATE output re-enabled)

Input Current

Current measurement sinse voltage

Accuracy of nominal V

Over-current sense threshold voltage 300 350 375 mV

threshold voltage

SENSE

IN

= V

=12V, TA = +25°C, unless otherwise specified.)

AUX

VIN or V

AUX

falling

rising

PWM pin floating. Output not switching

PWM pin grounded for more than 15ms

Sourcing 1mA -5

Sinking 100µA 5

VIN = V

, 6.5V<VIN = <60V

AUX

DC brightness control mode 10% to 200%

V

 2.5V

ADJ

= 5.0V†

V

ADJ

V

= 1.25V

ADJ

V

 2.5V

GI

= 5.0V†

V

GI

V

= 5.5V

PWM

PWM input low 10 15 25 ms

Temperature rising. 150 °C

Temperature falling. 125 °C

@ V

= 12V

ISM

Buck

Boost (Note 11) 225

V

ADJ

= 1.25V

Buck-Boost (Note 11)

V

= 1.25V

ADJ

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5.2 5.6 6.3 V

5.5 6.0 6.5 V

1.5 3.0 mA

150 300 µA

90 150 µA

0.7 10.0 µA

mV

-60 -90 dB

0.125 1.25 2.50 V

100

5

nA µA

0.8 V

100

5

nA µA

36 100 µA

11 20 µA

218

mV

±0.25 ±2 %

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ZXLD1370

Electrical Characteristics (cont.) (V

Symbol Parameter Conditions Min Typ Max Units

Output Parameters

V

FLAGL

I

FLAGOFF

V

STATUS

R

STATUS

Driver output (PIN GATE)

V

GATEH

V

GATEL

V

GATECL

I

GATE

t

STALL

LED Thermal control circuit (T

V

TADJH

V

TADJL

I

TADJ

Notes: 12. In the event of more than one fault/warning condition occurring, the higher priority condition will take precedence. E.g. ‘Excessive coil current’ and ‘Out of regulation’ occurring together will produce an output of 0.9V on the STATUS pin. The voltage levels on the STATUS output assume the Internal regulator to be in regulation and V minimum value of 6V.

13. Flag is asserted if V

14. GATE is switched to the supply voltage V internally to prevent it exceeding 15V.

15. GATE is switched to PGND by an NMOS transistor

16. If t grounded internally and the SHP pin is switched to its nominal operating voltage, before operation is allowed to resume. Restart cycles will be repeated automatically until the operating conditions are such that normal operation can be sustained. If t until normal operation is possible.

ZXLD1370

Document number: DS32165 Rev. 5 - 2

FLAG pin low level output voltage Output sinking 1mA 0.5 V

FLAG pin open-drain leakage current

STATUS Flag no-load output voltage (Note 12)

Output impedance of STATUS output Normal operation 10 k

High level output voltage

Low level output voltage Sinking 1mA, (Note 15) 0.5 V

High level GATE CLAMP voltage

Dynamic peak current available during rise or fall of output voltage

Time to assert ‘STALL’ flag and warning on STATUS output (Note 16)

) parameters

ADJ

Upper threshold voltage

Lower threshold voltage

T

pin Input current V

ADJ

<2.5V or V

exceeds t

ON

SHP

, the device will force GATE low to turn off the external switch and then initiate a restart cycle. During this phase, ADJ is

STALL

SHP

= V

IN

<=V

ADJ

>3.5V

for low values of V

AUX

=12V, TA = +25°C, unless otherwise specified.)

AUX

V

FLAG

=40V

1 µA

Normal operation 4.2 4.5 4.8

Out of regulation (V (Note 13)

VIN under-voltage (V

Switch stalled (tON or t

Over-temperature (TJ > +125°C)

Excess sense resistor current (V

> 0.32V)

SENSE

No load Sourcing 1mA (Note 14)

V

= V

AU X

= 1mA

= V

IN

I

GATE

Charging or discharging gate of external switch with Q

G

out of range)

SHP

< 5.6V)

IN

> 100µs)

OFF

= 18V

ISM

= 10nC and 400kHz

3.3 3.6 3.9

1.5 1.8 2.1

0.6 0.9 1.2

10 11 V

12.8 15.0 V

±300 mA

GATE low or high 100 170 µs

Onset of output current reduction (V

falling)

TADJ

Output current reduced to <10% of set value (V

TADJ

. A reduction of the voltage on the STATUS pin will occur when the voltage on VIN is near the

REF

falling)

TADJ

= 1.25V

(i.e. between 6V and approximately 12V). For V

AUX

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560 625 690 mV

380 440 500 mV

1 µA

>12V, GATE is clamped

AUX

exceeds t

OFF

, the switch will remain off

STALL

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P

PLY

CUR

REN

T

REFERENC

OLTAG

CUR

REN

T

N

G FACTO

R

Typical Characteristics

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ZXLD1370

1.252

2.5

2

t (mA)

1.5

1

S

0.5

0

6 121824 303642 485460

Figure 1 Supply Current vs. Supply Voltage

100%

80%

60%

SUPPLY VOLTAGE (V)

1.2515

1.251

E (V)

1.2505

1.25

E V

1.2495

1.249

1.2485

1.248

-40 -25 -10 5 20 35 50 65 80 95 110 125

1500

1250

1000

JUNCTION TEMPERATURE (°C)

Figure 2 V vs. Temperature

REF

DIMMI

40%

20%

LED

0%

0 250 500 750 1000 1250

ZXLD1370

Document number: DS32165 Rev. 5 - 2

T PIN VOLTAGE (mV)

ADJ

Figure 3 LED Current vs. T Voltage

ADJ

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750

500

LED CURRENT (mA)

250

0

0 1020304050 60708090100

PWM DUTY CYCLE (%)

Figure 4 I vs. PWM Duty Cycle

LED

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R

Q

C

CUR

RENT

UTY

Typical Characteristics (cont.)

1500

1250

1000

750

500

LED CURRENT (mA)

250

0

Figure 5 Buck LED Current, Switching Frequency vs. V

0.5 ADJ VOLTAGE (V)

1

1.5

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ZXLD1370

900

700 650

750

SWITCHING FREQUENCY (kHz)

600

550

500

600

450

300

150

0

2

2.5

ADJ

450

400

I

LED

350

300

Switc hing Frequency

250

LED CURRENT (mA)

200

150

100

50

0

0 0.5 1 1.5 2 2.5

ADJ VOLTAGE

T = 25°C

A

V = V = 24V

AUX IN

8LEDs

µ

L = 33 H GI = 0.23 R = 300m

S

Figure 6 Buck-Boost LED Current, Switching Frequency vs. V

1400

1200

SWITCHING FREQUENCY (kHz)

1000

800

600

400

200

Ω

0

ADJ

700 650

600

550

500

450

(mA)

400

I

LED

350

300

Switching Frequency

250

LED

200

150

100

50

0

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5

ADJ VOLTAGE

T = 25°C

A

V = V = 12V

AUX IN

12 LEDs L = 33 H

µ

R = 300m

Ω

S

Figure 7 Boost LED Current, Switching Frequency vs. V

700

600

500

400

300

200

100

0

ADJ

SWIT

HING F

E UEN

Y(kHz)

100%

T = 25C

90%

80%

A

L = 33µH R = 150m

S

Buck Mode 2 LEDS

70%

60%

50%

D

40%

30%

20%

10%

0%

6 121824303642485460

INPUT VOLTAGE (V)

Figure 8 Duty Cycle vs. Input Voltage

°

Ω

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CUR

RENT

TCHING F

REQ

UENC

Y (k

H

F

C

Y

Typical Characteristics (cont.) Buck Mode – R

1.500

1 LED 3 LEDs

1.490

T = 25C

°

A

V = V

1.480

(A)

AUX IN

1.470

1.460

LED

1.450

1.440

1.430

6.5 11 15.5 20 24.5 29 33.5 38 42.5 47 51.5 56 60.5

Figure 9 Load Current vs. Input Voltage & Number of LED

5 LEDs

= 150m, L = 33µH

S

7 LEDs 9 LEDs

INPUT VOLTAGE (V)

Diodes Incorporated

11 L EDs 13 LEDs

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ZXLD1370

15 LEDs

1000

1 LED 3 LEDs 5 L EDs 7 LEDs 9 LEDs 11 LED s 13 LEDs 15 LEDs

900

z)

800

700

T = 25°C

A

V = V

AUX IN

600

500

400

300

200

SWI

100

0

6.5 11 15.5 20 24.5 29 33.5 38 42.5 47 51.5 56 60.5

INPUT VOLTAGE (V)

Figure 10 Frequency vs. Input Voltage & Number of LED

100

95

90

85

(%)

80

IEN I

75

T = 25°C

E

A

V = V

AUX IN

70

65

60

6.5 11 15.5 20 24.5 29 33.5 38 42.5 47 51.5 56 60.5 INPUT VOLTAGE (V)

Figure 11 Efficiency vs. Input & Number of LED

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F

FIC

C

Y

Typical Characteristics (cont.) Buck Mode – R

0.740

0.735

0.730

0.725

LED CURRENT (A)

0.720

2 LEDs 3 LEDs 5 LEDs 7 LEDs 9 LEDs 11 L ED s 13 LEDs 15 LEDs

0.715

6.5 11 15.5 20 24.5 29 33.5 38 42.5 47 51.5 56 60.5

Figure 12 I vs. Input & Number of LED

1000

900

800

700

600

500

400

300

200

SWITCHING FREQUENCY (kHz)

100

0

100

2 LEDs 3 LEDs

T = 25°C

A

V = V

AUX IN

5 LEDs 7 LEDs 9 LEDs 11 L EDs 13 LEDs 15 LEDs

6.5 11 15.5 20 24.5 29 33.5 38 42.5 47 51.5 56 60.5

Figure 13 Frequency ZXLD1370 - Buck Mode - L47µH

= 300m, L = 47µH

S

INPUT VOLTAGE (V)

LED

INPUT VOLTAGE (V)

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T = 25°C

A

V = V

AUX IN

ZXLD1370

95

90

85

(%)

80

T = 25°C

IEN

75

A

V = V

AUX IN

E

70

2 LEDs 3 LEDs 5 LEDs 7 LEDs 9 LEDs 11 LED s 13 LEDs 15 LEDs

65

60

6.5 11 15.5 20 24.5 29 33.5 38 42.5 47 51.5 56 60.5 INPUT VOLTAGE (V)

Figure 14 Efficiency vs. Input Voltage & Number of LED

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Typical Characteristics (cont.) Boost Mode – R

0.400

0.350

0.300

0.250

0.200

0.150

LED CURRENT (A)

0.100

= 150m, GI

S

RATIO

Diodes Incorporated

= 0.23, L = 33µH

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T = 25°C

A

V = V

AUX IN

ZXLD1370

0.050

3 LEDs 4 LEDs 6 LEDs 8 LEDs 10 LEDs 12 LEDs 14 LEDs 16 LEDs

0.000

6.5 10 13.5 17 20.5 24 27.5 31 34.5 38 41.5 45 48.5 INPUT VOLTAGE (V)

500

450

400

Figure 15 I vs. Input Voltage & Number of LED

3 LEDs 4 LEDs 6 LEDs 8 LEDs 10 LEDs 12 LEDs 14 LEDs 16 LEDs

T = 25°C

A

V = V

AUX IN

LED

350

300

250

200

150

SWITCHING FREQUENCY (kHz)

100

50

6.51013.5

17

Boosted voltage across

LEDs approaching VIN

20.5 24 27.5 31 34.5 38 41.5 45 48.5 INPUT VOLTAGE (V)

Figure 16 Frequency vs. Input Voltage & Number of LED

100

3 LEDs

4 LEDs

6 LEDs 8 LEDs 10 LEDs

12 LEDs 14 LEDs 16 LEDs

95

90

85

80

75

EFFICIENCY (%)

70

T = 25°C

A

V = V

AUX IN

65

60

6.5 10 13.5 17

20.5

24 27.5 31 34.5 38 41.5 45 48.5

INPUT VOLTAGE (V)

Figure 17 Efficiency vs. Input Voltage & Number of LED

ZXLD1370

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