参数资料
型号: MAX16812ATI/V+
厂商: Maxim Integrated
文件页数: 11/21页
文件大小: 0K
描述: IC LED DRIVR HIGH BRIGHT 28-TQFN
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 60
恒定电流:
拓扑: PWM,SEPIC,降压(降压),升压(升压)
输出数: 1
内部驱动器:
类型 - 主要: 车载
类型 - 次要: 高亮度 LED(HBLED)
频率: 125kHz ~ 500kHz
电源电压: 5.5 V ~ 76 V
安装类型: 表面贴装
封装/外壳: 28-WFQFN 裸露焊盘
供应商设备封装: 28-TQFN-EP(5x5)
包装: 管件
工作温度: -40°C ~ 125°C
Integrated High-Voltage LED Driver
with Analog and PWM Dimming Control
High-Side Current-Sense Output (CS_OUT)
A high-side transconductance amplifier converts the
voltage across the LED current-sense resistor (R CS )
into an internal current output. This current flows
through an internal resistor connected to AGND. The
voltage gain for the LED current-sense signal is 4. The
amplified signal is then buffered and connected
through an internal switch to CS_OUT.
Internal Error Amplifier
The MAX16812 includes a built-in voltage-error amplifi-
er, which can be used to close the feedback loop. The
internal LED current-sense output signal is buffered
internally and then connected to CS_OUT through an
internal switch. CS_OUT is connected to the inverting
input (FB) pin of the error amplifier through a resistor.
See Figures 4 and 5. The reference voltage for the out-
put current is connected to REFI, the noninverting input
of the error amplifier. When the internal dimming signal
is low, COMP is disconnected from the output of the
error amplifier and CS_OUT is simultaneously discon-
nected from the buffered LED current-sense output sig-
nal (Figure 5). When the internal dimming signal is high,
the output of the op amp is connected to COMP and
CS_OUT is connected to the buffered LED current-
sense signal at the same time (Figure 4). This enables
the compensation capacitor to hold the charge when
the DIM signal has turned off the internal switching
MOSFET gate drive. To maintain the charge on the
compensation capacitors C COMP1 and C COMP2 , the
capacitors should be of the low-leakage ceramic type.
When the internal dimming signal is enabled, the voltage
on the compensation capacitor forces the converter into
steady state almost instantaneously. The voltage on
COMP is subtracted from the internal slope compensa-
tion signal and is then connected to one of the inputs of
the PWM comparator. The PWM comparator input is of
the CMOS type with very low bias currents.
C COMP2
X1
STATE A
OUT
R COMP1
R COMP2
EA
C COMP1
COMP
REFI
Figure 4. Internal Error Amplifier Connection (Dimming Signal High)
C COMP2
X1
STATE B
OUT
R COMP1
R COMP2
EA
C COMP1
COMP
REFI
Figure 5. Internal Error Amplifier Connections (Dimming Signal Low)
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11
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