AL1791/1792/1793/1794

Document number:37957 Rev. 3 - 2

3 of 18

www.diodes.com

September 2015

© Diodes Incorporated

AL1791/1792/1793/1794

EN

PWM1

PWM2

PWM3

FAULTB

REF

GND

LED1

LED2

LED3

3.3V

VIN

VLED1

Wireless/Color

management

MCU

AP3983C

AC-DC

Conversion

85~265Vac

AL1793

LEDPG

signal

VLED2

G

R

B

EN

PWM1

FAULTB

REF

GND

LED1

VIN

AL1791

LEDPG

W

Figure 4. 4-Channel White+Tunable RGB

Detailed Description

The AL1791, AL1792, AL1793, and AL1794 are single-channel, dual-channel, triple-channel, and four-channel, respectively, ratio-optimized

constant-current regulators optimized for Tunable White and Tunable Color, Smart Lighting applications. The maximum current channel can drive

up to 500mA with a total driving current up to 1.0A, 1.5A, and 1.5A for AL1792, AL1793, and AL1794 respectively. The maximum current for

AL1791 is 1A (refer to Table 1 below). The minimum channel current is recommended as in Table 2 in order to meet channel current accuracy and

short protection specifications. Each channel can still be individually controlled by either digital PWM dimming down to 0.10%@1KHz,

0.4%@4KHz, or 1.0%@10KHz or analog dimming. The integrated low-side current sinks allow LED common-anode connections for cost

effectiveness or different anode voltages for efficiency optimization.

AL179x

Channel 1

Channel 2

Channel 3

Channel 4

Total IC Current

AL1791

1.0A

X

X

X

1.0A

AL1792

0.5A

0.5A

X

X

1.0A

AL1793

0.5A

0.5A

0.5A

X

1.5A

AL1794

0.5A

0.5A

0.375A

0.125A

1.5A

Table 1 Recommended Maximum Channel Current and Total IC Current for AL179x

AL179x

Channel 1

Channel 2

Channel 3

Channel 4

Total IC Current

AL1791

0.2A

X

X

X

0.2A

AL1792

0.1A

0.1A

X

X

0.2A

AL1793

0.1A

0.1A

0.1A

X

0.3A

AL1794

0.1A

0.1A

0.075A

0.025A

0.3A

Table 2 Recommended Minimum Channel Current and Total IC Current for AL179x

The device detects fault conditions and reports its status on FAULTB pin. It features LED open detection, LED short detection, Over-Temperature

Protection (OTP), and Undervoltage Lockout (UVLO). The AL179x provides supreme current matching between channels and devices. Along with

bus-mode fault reporting, multiple devices can be employed together to increase current driving capability or channel count versatility.

Enable and Soft-Start

The AL179x is enabled when the voltage at EN pin is greater than approximately 2.5V, and disabled when it is lower than 0.4V. When EN pin is

asserted high and VIN pin is ramped up beyond minimum operation voltage, a soft-start will be performed with a slew-rate-controlled current ramp

over 100μS at LEDx output pins to minimize current overshoot through LED strings for optimal system reliability.