125mA 1x/1.5x Charge Pumps for 5 White LEDs
in 3mm x 3mm TDFN
Shutdown Mode
When both ENM and ENS (or PWM) are held low for
4ms or longer, the MAX8630_ is shut down and put in a
low-current mode. OUT is internally pulled to GND with
5k Ω during shutdown.
Overvoltage Protection
If any LED fails as an open circuit, the corresponding
V LED_ goes to 0V, and the output voltage is limited to
about 5V by gating on/off the charge pump. In case
any LED_ is floating or grounded, the MAX8630_ oper-
ates in the same overvoltage protection mode. To avoid
overvoltage protection mode when using fewer than
five LEDs, connect any unused LED_ to OUT. The
MAX8630_ contains special circuitry to detect this con-
dition and disables the corresponding current regulator
to avoid wasting battery current.
Thermal Shutdown
The MAX8630_ includes a thermal-protection circuit
that shuts down the IC when the die temperature reach-
es about +160°C. The part turns on after the IC cools
by approximately 20°C.
Temperature Derating Function
The MAX8630 contains a derating function that auto-
matically limits the LED current at high temperatures in
accordance with the recommended derating curve of
popular white LEDs. The derating function enables the
safe usage of higher LED currents at room tempera-
ture, thus reducing the number of LEDs required to
backlight the display. The derating circuit protects the
LEDs from overheating at high PCB temperatures. The
derating circuit limits the LED current by reducing the
internal 600mV reference voltage above +40°C at
approximately -1.67%/°C. The typical derating function
characteristic is shown in the Typical Operating
Characteristics .
Table 1. Recommended Components
Applications Information
Driving Fewer than 5 LEDs
To avoid overvoltage protection mode when using
fewer than five LEDs, connect any unused LED_ to
OUT. The MAX8630_ contains special circuitry to
detect this condition and disables the corresponding
current regulator to avoid wasting battery current.
Input Ripple
For LED drivers, input ripple is more important than out-
put ripple. Input ripple depends on the source supply’s
output impedance. Adding a lowpass filter to the input
of the MAX8630_ further reduces input ripple.
Alternatively, increasing C IN to 2.2μF (or 4.7μF) cuts
input ripple in half (or in fourth) with only a small
increase in footprint. The 1x mode always has very low
input ripple.
Component Selection
Ceramic capacitors are recommended due to their
small size, low cost, and low ESR. Select ceramic
capacitors that maintain their capacitance over temper-
ature and DC bias. Capacitors with X5R or X7R temper-
ature characteristics generally perform well. See Table
1 for a list of recommended components. Using a larg-
er value input capacitor helps to reduce input ripple
(see the Input Ripple section).
PCB Layout and Routing
The MAX8630_ is a high-frequency, switched-capacitor
voltage regulator. For best circuit performance, use a
solid ground plane and place C IN , C OUT , C1, and C2
as close to the MAX8630_ as possible. See the
MAX8630_ evaluation kit for an example layout.
Chip Information
PROCESS: BiCMOS
DESIGNATION
C IN , C OUT , C1, C2
D1–D5
VALUE
1μF
MANUFACTURER
Taiyo Yuden
TDK
Nichia
PART NUMBER
JMK105 BJ105MV
C1005X5R0J105M
NSCW215T
DESCRIPTION
1μF ±20%, 6.3V X5R ceramic capacitors (0402)
1μF ±20%, 6.3V X5R ceramic capacitors (0402)
White LEDs
_______________________________________________________________________________________
9
相关PDF资料
MAX8678EVKIT+ KIT EVAL FOR MAX8678
MAX9635EVKIT+ KIT EVAL FOR MAX9635
MB-1390-DG BRACKET EXTERNAL MOUNT DARK GRY
MB3CG-S1 CORD GRIP 7.5-10.5MM DIAM
MB3CG-S2 CORD GRIP 10.5-15MM DIAM
MB3CG-S3 CORD GRIP 15-17MM DIAM
MB3CG-S4 CORD GRIP 14.5-17MM DIAM
MBB02070C2205JRP00 RES 22M OHM 0.6W 5% 0207
相关代理商/技术参数
MAX8630YETD15 制造商:Maxim Integrated Products 功能描述:125MA 1X/1.5X CHARGE PUMPS FOR 5 WH - Rail/Tube
MAX8630YETD15+ 制造商:Maxim Integrated Products 功能描述:CHG PUMP STPUP/STPDN -0.3V TO 6V 125MA 14TDFN EP - Rail/Tube 制造商:Rochester Electronics LLC 功能描述:
MAX8630YETD15+T 功能描述:LED照明驱动器 125mA 1x/1.5x Charge Pump for 5 WLEDs RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N
MAX8630YETD15-T 功能描述:LED照明驱动器 125mA 1x/1.5x Charge Pump for 5 WLEDs RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N
MAX8630YETD18 制造商:Maxim Integrated Products 功能描述:125MA 1X/1.5X CHARGE PUMPS FOR 5 WH - Rail/Tube
MAX8630YETD18+ 制造商:Maxim Integrated Products 功能描述:CHG PUMP STPUP/STPDN -0.3V TO 6V 125MA 14TDFN EP - Rail/Tube
MAX8630YETD18+T 功能描述:LED照明驱动器 125mA 1x/1.5x Charge Pump for 5 WLEDs RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N
MAX8630YETD18-T 功能描述:LED照明驱动器 125mA 1x/1.5x Charge Pump for 5 WLEDs RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N