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参数资料
| 型号： | TC110333ECTRT |
| 元件分类： | 稳压器 |
| 英文描述： | 0.1 A SWITCHING CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封装： | EIAJ, SC-74A, SOT-23A, 5 PIN |
| 文件页数： | 11/13页 |
| 文件大小： | 93K |
| 代理商： | TC110333ECTRT |
7
TC110
PFM/PWM Step-Up DC/DC Controller
TC110-2 5/24/99
2001 Microchip Technology Inc.
DS21355A
Board Layout Guidelines
As with all inductive switching regulators, the TC110
generates fast switching waveforms which radiate noise.
Interconnecting lead lengths should be minimized to keep
stray capacitance, trace resistance and radiated noise as
low as possible. In addition, the GND pin, input bypass
capacitor and output filter capacitor ground leads should be
connected to a single point. The input capacitor should be
placed as close to power and ground pins of the TC110 as
possible.
Output Diode
For best results, use a Schottky diode such as the
MA735, 1N5817, MBR0520L or equivalent. Connect the
diode between the FB (or SENSE) input as close to the IC
as possible. Do not use ordinary rectifier diodes since the
higher threshold voltages reduce efficiency.
External Switching Transistor Selection
The EXT output is designed to directly drive an N-
channel MOSFET or NPN bipolar transistor. N-channel
MOSFETs afford the highest efficiency because they do not
draw any gate drive current, but are typically more expen-
sive than bipolar transistors. If using an N-Channel MOSFET,
the gate should be connected directly to the EXT output as
shown in Figure 1. EXT is a complimentary output with a
maximum ON resistances of 43
to VDD when high and 27
to ground when low. Peak currents should be kept below
10 mA.
When selecting an N-channel MOSFET, there are three
important parameters to consider: total gate charge (Qg);
ON resistance (rDS(on)) and reverse transfer capacitance
(CRSS). Qg is a measure of the total gate capacitance that
will ultimately load the EXT output. Too high a Qg can reduce
the slew rate of the EXT output sufficiently to grossly lower
operating efficiency. Transistors with typical Qg data sheet
values of 50 nC or less can be used. For example, the
Si9410DY has a Qg(typ) of 17nC @ VGS = 5V. This equates
to a gate current of:
IGATE(max) = fMAX x Qg = 115 KHZ x 17 nC = 2 mA
The two most significant losses in the N-Channel
MOSFET are switching loss and I
2R loss. To minimize
these, a transistor with low rDS(on) and low CRSS should
be used.
Bipolar NPN transistors can be used, but care must be
taken when determining base current drive. Too little current
will not fully turn the transistor on, and result in unstable
regulator operation and low efficiency. Too high a base drive
causes excessive power dissipation in the transistor and
increase switching time due to over-saturation. For peak
efficiency, make RB as large as possible, but still guarantee-
ing the switching transistor is completely saturated when the
minimum value of hFE is used.
APPLICATIONS
Circuit Design
Figure 3 shows a TC110 operating as a 100 KHz
bootstrapped regulator with soft start. This circuit uses an
NPN switching transistor (Zetex FZT690B) that has an hFE
of 400 and VCESAT of 100 mV at IC = 1A. Other high beta
transistors can be used, but the values of RB and CB may
need adjustment if hFE is significantly different from that of
the FZT690B.
Figure 4 and 5 both utilize an N-Channel switching
transistor (Silconix Si9410DY). This transistor is a member
of the Littlefoot
TM family of small outline MOSFETs. The
circuit of Figure 4 operates in bootstrapped mode, while the
circuit of Figure 5 operates in non-bootstrapped mode.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC110333ECTTR | 功能描述:开关变换器、稳压器与控制器 PFM/PWM Step-Up RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| TC1104 | 制造商:Thomas & Betts 功能描述:CABLE TIES |
| TC1105 | 制造商:Thomas & Betts 功能描述:CABLE MOUNTING STRIPS 5 BDL .5X6.8" 制造商:Thomas & Betts 功能描述:Cable Accessories Mounting Strip Nylon 6.6 Natural |
| TC110501ECT | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:PFM/PWM Step-Up DC/DC Controller |
| TC110501ECTTR | 功能描述:开关变换器、稳压器与控制器 PFM/PWM Step-Up RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
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