SSL21084T/1,118(2013) 查看數據表（PDF） - NXP Semiconductors.

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SSL21084T/1,118
(Rev.:2013)

Mains driver LED driver IC

NXP Semiconductors. 

NXP Semiconductors

SSL21084T

Mains dimmable LED driver IC

The value of ton(high) depends on the capacitor connected to the TONMOD pin. An open or

shorted TONMOD pin sets ton(high) to 15 s (see Section 8.4.6 and Table 6).

8.5 VCC supply

The SSL21084T can be supplied using three methods:

• Under normal operation, the voltage swing on the DVDT pin is internally rectified to

provide current on the VCC pin

• At start-up, there is an internal current source connected to the HV pin. The current

source provides internal power until either the dV/dt supply or an external current on

the VCC pin provides the supply.

• Using an auxiliary winding, the voltage can be rectified and connected to the VCC pin

via a series resistor.

The IC starts up when the voltage at the VCC pin exceeds VCC(startup). The IC locks out

(stops switching) when the voltage on the VCC pin is lower than VCC(stop). The hysteresis

between the start and stop levels allows the IC to be supplied by a buffer capacitor until

the external supply is stable. The SSL21084T has an internal VCC clamp, which is an

internal active Zener (or shunt regulator). This internal active Zener limits the voltage on

the supply VCC pin to the maximum value of VCC. If the maximum current of the supply

minus the current consumption of the IC (determined by the load on the gate drivers), is

lower than the maximum value of IDD, an external Zener diode is not needed in the supply

circuit.

8.5.1 VCC regulator

During supply dips, the input voltage can drop too low to supply the required IC current.

Under these conditions, if the VCC voltage drops lower than VCC(swon)reg level, a second

regulator is started. Its function is to fill in the required supply current which the external

supply does not deliver. It prevents the IC going into UVLO. When the VCC voltage

exceeds VCC(swon)reg level, the regulator is turned off.

8.6 DVDT pin supply (dV/dt)

The DVDT pin is connected to an internal single-sided rectification stage. When an

alternating voltage with sufficient amplitude is supplied to this pin, the IC can be powered

without another external power connection. This provides a compact and effective solution

without introducing high power losses and without requiring an additional inductor

winding.

8.7 NTC functionality and PWM dimming

The NTC pin can be used as a control method for LED thermal protection. Alternatively,

the pin can be used as an input to disable/enable light output using a digital signal (PWM

dimming). The pin has an internal current source that generates the current of Ioffset(NTC).

An NTC resistor to monitor the LED temperature can be directly connected to the NTC

pin. Depending on the resistance value and the corresponding voltage on the NTC pin,

the converter reacts as shown in Figure 6.

SSL21084T

Product data sheet

All information provided in this document is subject to legal disclaimers.

Rev. 6 — 3 October 2013

© NXP B.V. 2013. All rights reserved.

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