ZLED7520ZI1R ZMDI, ZLED7520ZI1R Datasheet - Page 14

• Manufacturer Part Number: ZLED7520ZI1R
• Description: LED Lighting Drivers LED driver
• Manufacturer: ZMDI

Specifications of ZLED7520ZI1R

• Rohs: yes
• Input Voltage: 6 V to 40 V
• Operating Frequency: 1 MHz
• Maximum Supply Current: 600 uA
• Output Current: 0.75 A
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• Package / Case: DFN-5
• Minimum Operating Temperature: - 40 C
• Power Dissipation: 500 mW

2.4
An external pulse width modulation (PWM) control signal input on the ADJ pin can be used for brightness or gated
on/off control of the output current by driving the output current to a value below the nominal average current
determined by R
within the range of 0 to 5 V. The logic high level must be higher than 1.2V and the logic low level must be below
0.2V. It must be capable of driving the ADJ pin’s input impedance R
resistor to V
2.5
An external control signal from the open drain output of a microcontroller can provide on/off or PWM brightness
control by driving the ADJ pin. See Figure 3.4 for a typical application circuit. Diode D2 and resistor R1 shown in
Figure 3.4 suppress any negative high-amplitude spikes on the ADJ input due to the drain-source capacitance of
the FET in the microcontroller’s output. Negative spikes on the ADJ input could cause output current errors or
unintended ZLED7x20 operation. The signal input to the ADJ pin must be capable of driving the ADJ pin’s input
impedance R
2.6
If the ADJ pin voltage V
a low standby level (I
will switch the output back to full operational mode.
2.7
2.7.1
The ZLED7x20 automatically protects itself from damage due to over-temperature conditions. If the ZLED7x20’s
temperature exceeds the thermal shutdown threshold (T
avoid erratic ZLED7x20 operation, a 20K hysteresis (T
until its temperature falls below the hysteresis threshold (T
thermal considerations.
2.7.2
As a step-down converter, the ZLED7x20 has inherent open-load circuit protection. Since the L1 inductor is
connected in series with the LED string, the current flow is interrupted if the load is open and the LX output of the
ZLED7x20 will not be damaged. This provides an advantage over other products such as boost converters, for
which the internal switch can be damaged by back EMF forcing the drain above its breakdown voltage.
Data Sheet
August 12, 2011
ZLED7520
High Current 40V LED Driver with Internal Switch
Control of Output Current via a PWM Signal on the ADJ Pin
Control of Output Current via a Microcontroller Signal on the ADJ Pin
Shutdown Mode
ZLED7x20 Protection Features
Thermal Shut-down Protection
LED Open Load Protection
REF
ADJ
).
S
(approximately 500k ; internal pull-up resistor to VREF).
. See Figure 3.3 for a typical application circuit. The PWM or gated on/off control signal can be
© 2011 Zentrum Mikroelektronik Dresden AG — Rev. 1.2
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without
the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.
INQoff
ADJ
= 120µA nominal). Raising the ADJ pin voltage so that V
is ≤ V
ADJoff
(0.2V ± 0.05V), the supply current and output on the LX pin are quiescent at
SD-HYS
SD
) is applied that prevents it from returning to operation
SD
= 150° C, typical), the ZLED7x20 will shutdown. To
- T
SD-HYS
ADJ
). Also refer to section 3.2 for additional
(approximately 500k ; internal pull-up
ADJ
≥ V
ADJion
(0.25V ± 0.05V)
14 of 27