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参数资料
| 型号： | LTC3823EUH#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 16/26页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 32-QFN |
| 标准包装： | 73 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 90% |
| 电源电压： | 4.5 V ~ 36 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 包装： | 管件 |
LTC3823
APPLICATIONS INFORMATION
INTV CC Regulator
An internal P-channel low dropout regulator produces the
5V supply that powers the drivers and internal circuitry
within the LTC3823. The INTV CC pin can supply up to 50mA
RMS and must be bypassed to ground with a minimum
of 4.7μF low ESR tantalum capacitor or other low ESR
capacitor. Good bypassing is necessary to supply the high
transient currents required by the MOSFET gate drivers.
Applications using large MOSFETs with a high input voltage
and high frequency of operation may cause the LTC3823
to exceed its maximum junction temperature rating or
RMS current rating. Most of the supply current drives the
MOSFET gates. In continuous mode operation, this current
is I GATECHG = f(Q g(TOP) + Q g(BOT) ). The junction temperature
can be estimated from the equations given in Note 2 of the
Electrical Characteristics. For example, the GN package is
limited to less than 23mA from a 30V supply:
T J = 70°C + (23mA)(30V)(80°C/W) = 125°C
For applications where more current is needed than INTV CC
can supply, INTV CC can be driver by an external supply
with a voltage higher than 5.35V. However, the INTV CC pin
should not exceed its absolute maximum voltage of 7V.
External Gate Drive Buffers
The LTC3823 drivers are adequate for driving up to about
50nC into MOSFET switches with RMS currents of 50mA.
Applications with larger MOSFET switches or operating
at frequencies requiring greater RMS currents will bene?t
from using external gate drive buffers such as the LTC1693.
Alternately, the external buffer circuit shown in Figure 6
can be used.
Soft-Start and Tracking
The LTC3823 has the ability to either soft start by itself with
a capacitor or track the output of another supply. When
the device is con?gured to soft start by itself, a capacitor
should be connected to the TRACK/SS pin. The LTC3823
is put in a low quiescent current shutdown state (30μA)
if the RUN pin voltage is below 1.5V. The TRACK/SS
pin is actively pulled to ground in this shutdown state.
Once the RUN pin voltage is above 1.5V, the LTC3823 is
powered up. A soft-start current of 1.7μA then starts to
charge the soft-start capacitor C SS . Pin Z1/SS ENABLE must
be grounded for soft-start operation. Note that soft-start
is achieved not by limiting the maximum output current
of the controller but by controlling the ramp rate of the
output voltage. Current foldback is disabled during this
soft-start phase. During the soft-start phase, the LTC3823
is ramping the reference voltage until it is 20% below the
voltage set by the V REFIN pin. The forced continuous mode
is also disabled and PGOOD signal is forced low during this
phase. The total soft-start time can be calculated as:
t SOFTSTART = 0.5V ? C SS /1.7μA
When the device is con?gured to track another supply,
the feedback voltage of the other supply is duplicated by
a resistor divider and applied to the TRACK/SS pin. Pin
Z1/SS ENABLE should be tied to INTV CC to turn off the soft-
start current in this mode. Therefore, the voltage ramp rate
on this pin is determined by the ramp rate of the other
supply output voltage.
Output Voltage Tracking
The LTC3823 allows the user to program how its output
BOOST
INTV CC
ramps up and down by means of the TRACK/SS pin.
Through this pin, the output can be set up to either co-
TG
10Ω
Q1
FMMT619
GATE
OF M1
Q2
FMMT720
BG
10Ω
Q3
FMMT619
GATE
OF M2
Q4
FMMT720
incidentally or ratiometrically track with another supply’s
output, as shown in Figure 7. In the following discussions,
V OUT1 refers to the master LTC3823’s output and V OUT2
refers to the slave LTC3823’s output.
SW
PGND
3823 F06
To implement the coincident tracking in Figure 7a, connect
Figure 6. Optional External Gate Driver
an additional resistive divider to V OUT1 and connect its
midpoint to the TRACK/SS pin of the slave IC. The ratio of
this divider should be selected the same as that of the slave
IC’s feedback divider shown in Figure 8. In this tracking
3823fd
16
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相关代理商/技术参数 |
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| LTC3823IGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC3823IGN#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN DC/DC CTRL SSOP-28 |
| LTC3823IGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3823IUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC3823IUH#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN DC/DC CONTROLLER QFN32 |
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