ZXSC400E6TA Diodes Zetex, ZXSC400E6TA Datasheet - Page 7

• Manufacturer Part Number: ZXSC400E6TA
• Description: IC LED DRVR WHITE BCKLGT SOT23-6
• Manufacturer: Diodes Zetex
• Type: Backlight, White LEDr

Specifications of ZXSC400E6TA

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Backlight, Flash/Torch
• Type - Secondary: High Brightness LED (HBLED), White LED
• Frequency: 200kHz
• Voltage - Supply: 1.8 V ~ 8 V
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 50mA
• Internal Switch(s): Yes
• Efficiency: 80%
• Operating Supply Voltage (typ): 2.5/3.3/5V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Package Type: SOT-23
• Pin Count: 6
• Mounting: Surface Mount
• Power Dissipation: 450mW
• Operating Supply Voltage (min): 1.8V
• Operating Supply Voltage (max): 8V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Compliant
• Other names: ZXSC400E6TATR

Open-circuit protection
For applications where the LED chain might go
open-circuit a Zener diode can be connected across the
LED chain preventing over-voltage and possible
damage to the main switching transistor. The Zener
diodes should be selected by ensuring its voltage
rating is higher than the combined forward voltage of
the LED chain. Under open circuit conditions the curren
in the Zener diode defines the output current as:
The circuit example below give an open circuit output
current of 300 A.
Dimming Control
There are four types of dimming control that can be
implemented for the ZXSC400.
ISSUE 1 - JANUARY 2003
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Dimming Control using the shutdown pin
The first method uses the shutdown pin. By injecting a
PWM waveform on this pin and varying the duty cycle,
LED current and hence LED brightness can be adjusted.
To implement this method of brightness control on the
ZXSC400, apply PWM signal with amplitude of
between 0.7V and Vcc at a frequency of 120Hz or above
(to eliminate LED flicker). The LED current and hence
LED brightness is linearly proportional to the duty cycle
ratio, so for brightness control adjust duty cycle ratio as
necessary. For example, a 10% duty cycle equates to
10% of full LED brightness.
ZXSC400