A Product Line of
Diodes Incorporated
ZXLD1374
60V HIGH ACCURACY 1.5A BUCK/BOOST/BUCK-BOOST
LED DRIVER CONVERTER WITH AEC-Q100
Description Pin Assignments
The ZXLD1374 is a 60V LED driver with integrated 1.5A low side
ADJ 1 20 GI
switch to drive high current LEDs. It is a multi-topology converter
enabling it to operate in Buck, Boost and Buck-boost configurations;
REF 2 19 PWM
efficiently controlling the current of up to 16-series connected LEDs.
TADJ 3 18 FLAG
The ZXLD1374 is a modified hysteretic converter using a patent
SHP 4 17 ISM
pending control scheme providing high output current accuracy in all
STATUS 5 Thermal 16 VIN
three topologies. High accuracy dimming is achieved through
DC control and high frequency PWM control.
SGND 6 Pad 15 VAUX
The ZXLD1374 uses two pins for fault diagnosis. A flag output
PGND 7 14 LX
highlights a fault, while the multi-level status pin gives further
PGND 8 13 LX
information on the exact fault.
N/C 9 12 N/C
The ZXLD1374 has been qualified to AEC-Q100 Grade 1 enabling
N/C 10 11 N/C
operation in ambient temperatures from -40 to +125C.
Features
0.5% Typical Output Current Accuracy
6.3 to 60V Operating Voltage Range
1.5A Integrated Low Side Switch
LED Driver Supports Buck, Boost and Buck-Boost Topologies
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
AEC-Q100 Grade 1
TSSOP-20EP: 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
A Product Line of
Diodes Incorporated
ZXLD1374
Pin Descriptions
Pin Type
Pin Function
Name (Note 4)
Adjust Input (for DC Output Current Control).
Connect to REF to set 100% output current.
ADJ 1 I
Drive with dc voltage (125mV<V < 2.5V) to adjust output current from 10% to 200% of set value. The
ADJ
ADJ pin has an internal clamp that limits the internal node to less than 3V. This prevents the LED and power
switch from delivering too much current should ADJ get overdriven.
REF 2 O Internal 1.25V reference voltage output
Temperature Adjust (Input for LED Thermal Current Control).
T 3 I Connect thermistor/resistor network to this pin to reduce output current above a preset temperature threshold.
ADJ
Connect to REF to disable thermal compensation function (See section on thermal control).
Shaping capacitor for feedback control loop.
SHP 4 I/O
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.
STATUS 5 O
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.
Signal Ground.
SGND 6 P
Connect to 0V and pins 7 and 8.
Power Ground.
PGND 7, 8 P
Connect to 0V and pin 6 to maximize copper area.
Not Connected Internally.
N/C 9, 10, 11, 12
To maximize PCB copper for thermal dissipation connect to pins 7 and 8.
LX 13, 14 O Low-Side Power-Switch Output
Auxiliary Positive Supply to Internal Switch Gate Driver.
Connect to V , or auxiliary supply from 6V to 15V supply to reduce internal power dissipation (Refer to
IN
application section for more details).
V 15 P
AUX
At V >24V; to reduce power dissipation, V can be connected to a 12V to 15V auxiliary power supply
IN AUX
(see Applications section).
Decouple to ground with capacitor close to device (refer to Applications section).
Input Supply to Device (6.3V to 60V).
16 P
V
IN
Decouple to ground with capacitor close to device (refer to Applications section).
Current Monitor Input.
Connect current sense resistor between this pin and V .
IN
ISM 17 I
The nominal voltage, V , across the resistor is 218mV fixed in Buck mode and initially 225mV in Boost
SENSE
and Buck-Boost modes, varying with duty cycle.
Flag Open Drain Output.
FLAG 18 O 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.
PWM 19 I 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 LED current in Boost and Buck-Boost modes.
In Buck mode operation the GI pin must be connected to ADJ.
GI 20 I
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 node to less than 3V. This provides some failsafe should the GI pin get overdriven.
Exposed Pad.
EP PAD P
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.
2 of 39 September 2012
ZXLD1374
Diodes Incorporated
www.diodes.com
Document number: DS35032 Rev. 3 - 2