ZXLD1371 datasheet(4/42 Pages) DIODES

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ZXLD1371

Document number: DS35436 Rev. 1 - 2

4 of 42

www.diodes.com

February 2012

A Product Line of

Diodes Incorporated

Package Thermal Data

Thermal Resistance

Package

Typical

Unit

Junction-to-Ambient,

θJA (Note 4)

TSSOP-16 EP

°C/W

Junction-to-Case,

θJC

TSSOP-16 EP

°C/W

Recommended Operating Conditions (-40°C ≤ TJ ≤ 125°C)

Symbol

Parameter

Performance/Comment

Min

Max

Unit

VIN

Input supply voltage range

Normal Operation

8.0

(Note 5) Reduced performance

operation

5.0

8.0

VAUX

Auxiliary supply voltage range (Note 6)

Normal Operation

8.0

(Note 5) Reduced performance

operation

5.0

8.0

VSENSE

Differential input voltage

VIN-VISM, with 0 ≤ VADJ ≤ 2.5

450

VADJ

External dc control voltage applied to ADJ pin to

adjust output current

DC brightness control mode

from 10% to 100%

0.125

1.25

IREF

Reference external load current

REF sourcing current

fmax

Recommended switching frequency range

(Note 7)

300

1000

kHz

VTADJ

Temperature adjustment (TADJ) input voltage range

VREF

fPWM

Recommended PWM dimming frequency range

To achieve 1000:1 resolution

100

500

To achieve 500:1 resolution

100

1000

tPWMH/L

PWM pulse width in dimming mode

PWM input high or low

0.002

VPWMH

PWM pin high level input voltage

5.5

VPWML

PWM pin low level input voltage

0.4

Operating Junction Temperature Range

-40

125

°C

Gain setting ratio for boost and buck-boost modes

Ratio= VGI/VADJ

0.20

0.50

Notes:

3. For correct operation SGND and PGND should always be connected together.

4. Measured on “High Effective Thermal Conductivity Test Board" according to JESD51.

5. Device starts up above 5.4V and as such the minimum applied supply voltage has to be above 5.4V (plus any noise margin). The ZXLD1371 will,

however, continue to function when the input voltage is reduced from

≥ 8V down to 5.0V.

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, VIN, between 5.0 and 8V a suitable boot-strap network on VAUX pin is recommended.

Performance in Buck mode will be reduced at input voltages (VIN, VAUX) below 8V. – a boot-strap network cannot be implemented in buck mode.

6. VAUX 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

not be applied to VAUX in the absence of a voltage at VIN. VAUX can also be operated at a lower voltage than VIN to increase efficiencies at high

VIN.

7. The device contains circuitry to control the switching frequency to approximately 400kHz. The maximum and minimum operating frequency is not

tested in production.

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