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参数资料
| 型号： | LT1768CGN |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | High Power CCFL Controller for Wide Dimming Range and Maximum Lamp Lifetime |
| 中文描述： | 1.5 A FLUORESCENT LIGHT CONTROLLER, 410 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | 0.150 INCH, PLASTIC, SSOP-16 |
| 文件页数： | 14/20页 |
| 文件大小： | 301K |
| 代理商： | LT1768CGN |
LT1768
14
up current source. The LT1768 thermal shutdown tem-
perature is set at 160
°
C. A buffered version of the internal
5V is present at the V
REF
pin and is capable of supplying up
to 10mA of current. Note that using any substantial
amount of current from the V
REF
pin will increase power
dissipation in the device, which will reduce the useful
operating ambient temperature range.
Supply and Input Voltage Sequencing
For most applications, where the SHDN pin is left floating,
and the voltages on the PWM and PROG pins are derived
from the V
REF
pin, the LT1768 will power-up and power-
down correctly when the voltage to the V
IN
pin is applied
and removed. In applications where the voltage inputs for
the V
IN
pin, SHDN pin, PWM pin, and the PROG pin
originate from different sources (power supply, micropro-
cessors etc.), care must be taken during power up/down
sequences. For proper operation during the power-up
sequence, the voltage on the following pins must be taken
from zero to their appropriate values in the following
order; V
IN
pin, SHDN pin, PWM pin and PROG pin. For
proper operation during the power-down sequence, the
order must be reversed. For example, in the circuit of
Figure 1 where the SHDN pin is left floating, and the PWM
pin voltage is derived from a resistor divider to the V
REF
pin, the proper power-up sequence would be to take the
V
IN
pin from zero to its value then apply either a voltage or
PWM signal to the PROG pin. The power-down sequence
for the circuit in Figure 1 would be to take the PROG pin
voltage to zero, then take the V
IN
pin voltage to zero.If the
PROG voltage in the circuit of Figure 1 is present before the
V
IN
supply voltage, proper power supply sequecing can be
achieved by implementing the circuit shown in Figure 7.
APPLICATIO
S I
FOR
ATIO
U
GATE
The LT1768 has a single high current totem pole output
stage. This output stage is capable of driving up to
±
1.5A
of output current. Cross-conduction current spikes in the
totem pole output have been eliminated. The GATE pin is
intended to drive an N-channel MOSFET switch. Rise and
fall times are typically 50ns with a 3000pF load. A clamp
is built into the device to prevent the GATE pin from rising
above 13V in order to protect the gate of the MOSFET
switch.
The GATE pin connects directly to the emitter of the upper
NPN drive transistor and the collector of the lower NPN
drive transistor in the totem pole. The collector of the lower
transistor, which is N-type silicon, forms a P-N junction
with the substrate of the device. This junction is reversed
biased during normal operation.
In some applications the parasitic LC of the external
MOSFET gate can ring and pull the GATE pin below
ground. If the GATE pin is pulled negative by more than a
diode drop the parasitic diode formed by the collector of
the GATE NPN and the substrate will turn on. This can
cause erratic operation of the device. In these cases a
Schottky clamp diode is recommended from the GATE pin
to ground. (Figure 6.)
W
U
U
1768 G06
PGND
GATE
BAT 85
LT1768
Figure 6. Schottky Gate Clamp
49.9k
10k
10
μ
F
0 TO 5V
OR
1kHz PWM
VN2222LL
1768 F07
V
IN
PROG
LT1768
Figure 7. Circuit Insures Proper Supply Sequencing When
Dimming Voltage Exists Before Main Power Supply
Reference
The internal reference of the LT1768 is a trimmed bandgap
reference. The reference is used to power the majority of
the LT1768 internal circuitry. The reference is inactive if
the LT1768 is in undervoltage lockout, shutdown mode, or
thermal shutdown. The undervoltage lockout is active
when V
IN
is below 7.9V and the LT1768 is in shutdown
mode when the voltage on the SHDN pin is pulled below
1V. The SHDN pin has 200mV of hysteresis and a 7
μ
A pull-
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1768CGN#PBF | 功能描述:IC CTRLR CCFL SGL/MULT HP 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 照明，镇流器控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:CCFL 控制器 频率:40 ~ 80 kHz 电流 - 电源:5mA 电流 - 输出:- 电源电压:4.5 V ~ 5.5 V 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC 包装:带卷 (TR) 其它名称:90-3991V+V01 |
| LT1768CGN#TR | 功能描述:IC CTRLR CCFL SGL/MULT HP 16SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 照明，镇流器控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:CCFL 控制器 频率:40 ~ 80 kHz 电流 - 电源:5mA 电流 - 输出:- 电源电压:4.5 V ~ 5.5 V 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC 包装:带卷 (TR) 其它名称:90-3991V+V01 |
| LT1768CGN#TRPBF | 功能描述:IC CTRLR CCFL SGL/MULT HP 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 照明，镇流器控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:CCFL 控制器 频率:40 ~ 80 kHz 电流 - 电源:5mA 电流 - 输出:- 电源电压:4.5 V ~ 5.5 V 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC 包装:带卷 (TR) 其它名称:90-3991V+V01 |
| LT1768IGN | 功能描述:IC CTRLR CCFL SGL/MULT HP 16SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 照明，镇流器控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:CCFL 控制器 频率:40 ~ 80 kHz 电流 - 电源:5mA 电流 - 输出:- 电源电压:4.5 V ~ 5.5 V 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC 包装:带卷 (TR) 其它名称:90-3991V+V01 |
| LT1768IGN#PBF | 功能描述:IC CTRLR CCFL SGL/MULT HP 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 照明，镇流器控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:CCFL 控制器 频率:40 ~ 80 kHz 电流 - 电源:5mA 电流 - 输出:- 电源电压:4.5 V ~ 5.5 V 工作温度:-40°C ~ 85°C 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC 包装:带卷 (TR) 其它名称:90-3991V+V01 |
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