|
|
PDF NJU6053 Data sheet ( Hoja de datos )
| Número de pieza | NJU6053 | |
| Descripción | White LED Driver / QFN28-P4 | |
| Fabricantes | JRC | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de NJU6053 (archivo pdf) en la parte inferior de esta página. Total 25 Páginas | ||
|
No Preview Available !
www.DataSheet4U.com
Preliminary
NJU6053
PRELIMINARY
White LED Driver with Automatic Dimming Control
! GENERAL DESCRIPTION
The NJU6053 is a white LED driver with an automatic
dimming control. It contains an output driver, a PWM
controller, a luminance sensor control (power supply for
sensor & A/D converter), a step-up DC/DC converter, a
serial interface, etc.
The NJU6053 can turn three independent lighting
circuits on/off separately or simultaneously with
instruction.
The output driver ensures a 40mA maximum capability
which allows the connection of 12 white LEDs (4 series x
3 parallels). Depending on the ambient light sensed with
an external luminance sensor, the PWM controller
controls PWM duty in 8 steps preselected out of 64 steps.
In addition, the frequency of the DC/DC converter is high
so that it permits the use of small, low-profile inductors
and capacitors to minimize the footprint in
space-conscious applications.
All of these benefits make the NJU6053 suitable for the
battery-powered portable applications such as a cellular
phone, a camcorder, PDA, etc.
! PACKAGE OUTLINE
NJU6053KP4
! FEATURES
# Drives up to 12 white LEDs (4 series x 3 parallels)
# Controls 3 outputs separately
VSW = 18.0V(Max), IOUT = 40mA
# Built-in PWM Dimming Control
(Selectable 8 out of 64 steps)
# Built-in Luminance Sensor Control (Power Supply for Sensor & A/D converter)
(No MPU-access required after initial setting)
# Built-in Temperature Compensation Circuit to Suppress the Characteristic Degradation of LEDs
# Uses Small Inductor and Capacitors
# 1.8V to 3.6V Operating Voltage for Logic Circuits (VDDL)
# 3.0V to 5.5V Operating Voltage for Step-up Circuits (VDD)
# CMOS Technology
# Package
: QFN28
Ver.2004-02-26
-1-
1 page  
www.DataSheet4U.com
Preliminary NJU6053
! FUNCTIONAL DESCRIPTONS
(1) LED CURRENT CONTROL
The NJU6053 incorporates the LED current control circuit to regulate the LED current (ILED), which is
programmed by the feedback resistor (RLED) connected between the FB and VSS terminals. The reference
voltage VREF is internally regulated to 0.6V typical and connected to the positive input of the built-in comparator
A1. Formula (1) is used to choose the value of the RLED, as shown below.
RLED = VREF / ILED
VREF=0.6V (typ.)
--- Formula (1)
Referring to the block diagram is recommended for understanding the operation of the LED current control.
The ILED is the constant current programmed by the RLED. When the feedback voltage on the FB terminal
reaches above the reference voltage VREF on the REF terminal (i.e., ILED is above the level programmed by
RLED), the output capacitor C2 delivers the ILED. Once the feedback voltage drops below the reference voltage
(i.e., ILED drops below the level programmed by RLED), the comparator A1 detects it and turns on the internal
MOS switch, then the current of the inductor L1 begins increasing. When this switch current reaches 720mA
and the comparator A2 detects it, or when the predetermined switch-on-period expires, the MOS switch is
turned off. The L1 then delivers current to the output through the diode D1 as the inductor current drops. After
that, the MOS switch is turned on again and the switch current increases up to 720mA. This switching cycle
continues until the ILED reaches the level programmed by the RLED, then the ILED is maintained constant.
When the feedback voltage is less than 1/2*VREF, the current limit of the MOS switch is reduced to 550mA
typical. This action reduces the average inductor-current, minimizes the power dissipation and protects the IC
against high current at start-up.
The total forward-voltage of the LEDs must be greater than the power supply voltage VDD, otherwise the
LEDs remain lighting up, being out of control.
(2) OUTPUT SWITCH CIRCUIT
With built-in LED control and feedback circuits, NJU6053 can control LEDs on/off with software. But the
maximum total output current can not exceed 40 mA.
NJU6053 can turn LEDs in string on or off respectively via LED control pins, but can not make LED dimming
control for individual lighting circuit. Corresponding to the lighted LEDs, one of three feedback pins (FB1 to
FB3) become active. For details of relationship between the lighted LED and feedback pin, refer to (6) Serial
Interface.
(3) OSCILLATOR
The built-in oscillator incorporates a reference power supply, so its frequency is independent from the VDD.
The frequency is varied by the external capacitor CX, as shown in Figure 7.
(4) LUMINANCE SENSOR CONTROL
The luminance sensor control circuits consist of the power supply for sensor and the A/D converter. The A/D
converter senses the voltage on the SENS terminal and selects 1 out of 8 registers (PWM REGISTER 0–7).
And the data in the selected register is reflected to the PWM duty (PWM dimming control). The contents of the
registers can be programmed through the serial interface, in other words, the dimming control is user-settable.
The voltage sense and the register selection are updated at regular intervals, and the interval period is set by
the “DIVIDE” bits. The selected register is held by setting “1” at the “HOLD” bit of the command data.
Ver.2004-02-26
-5-
5 Page 
www.DataSheet4U.com
Preliminary NJU6053
(7) LEVEL SHIFTER
The level shifter allows the communication with the MPU working at the power supply voltage lower than the
VDD. Apply the MPU power-supply-voltage on the VDDL terminal. The voltage range is: 1.8V≤VDDL≤3.6V .
(8) RESET
By setting the RSTb pin to “L”, the NJU6053 is initialized into the following default status.
TABLE 8 RESET
1. REV
2. HOLD
3. STBY
4. BRIGHT
5. SOFF
6. DIVIDE
7. C1,C2,C3
8. INV
9. PWM REGISTER 0
10. PWM REGISTER 1
11. PWM REGISTER 2
12. PWM REGISTER 3
13. PWM REGISTER 4
14. PWM REGISTER 5
15. PWM REGISTER 6
16. PWM REGISTER 7
: (0)
: (0)
: (0)
: (0,0,0)
: (0)
: (0,0)
: (0,0,0)
: (0)
: (0,0,0,0,0,0)
: (0,0,0,0,0,0)
: (0,0,0,0,0,0)
: (0,0,0,0,0,0)
: (0,0,0,0,0,0)
: (0,0,0,0,0,0)
: (0,0,0,0,0,0)
: (0,0,0,0,0,0)
Refer to Table 5
Sensor sampling is enabled
Standby Off
Luminance sensor control is enabled
DUTY 0% (LED OFF)
DUTY 0% (LED OFF)
DUTY 0% (LED OFF)
DUTY 0% (LED OFF)
DUTY 0% (LED OFF)
DUTY 0% (LED OFF)
DUTY 0% (LED OFF)
DUTY 0% (LED OFF)
(9) TEMPERATURE COMPENSATION
The reference voltage (VREF) generator has temperature compensation, which suppresses the characteristic
degradation of LEDs at high temperatures. Refer to “ILED vs. Temperature” shown in the “DC Electrical
Characteristics”.
(10) APPLICATIONS INFORMATION
(10-1) PWM DUTY and LED CURRENT
The average LED current is programmed with the single resistor RLED and the PWM duty, as shown in
Formula (4).
I LED(avg)
=
I LED(max)
⋅
DUTY
100
I LED(max)
=
VREF
R LED
--- Formula (4)
(10-2) INDUCTOR SELECTION
Formula (5) is used to choose an optimum inductor, as shown below:
L
=
2
VOUT
η
− VIN ⋅ ILED
I2
LIMIT
⋅
f OSC
--- Formula (5)
η : Power conversion efficiency (= 0.7 to 0.8)
Ver.2004-02-26
- 11 -
11 Page | ||
| Páginas | Total 25 Páginas | |
| PDF Descargar | [ Datasheet NJU6053.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| NJU6050 | White LED Driver / SOT-23(MTP5) | JRC |
| NJU6051 | White LED Driver / QFN20-M1 / SSOP20 | JRC |
| NJU6052 | White LED Driver / QFN28-N1 / SSOP20 | JRC |
| NJU6053 | White LED Driver / QFN28-P4 | JRC |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |