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参数资料
| 型号： | TC828AECT |
| 元件分类： | 稳压器 |
| 英文描述： | 0.05 A SWITCHED CAPACITOR CONVERTER, 20 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封装： | SOT-23A, 5 PIN |
| 文件页数： | 3/8页 |
| 文件大小： | 60K |
| 代理商： | TC828AECT |
3
TC828A
Switched Capacitor
Voltage Converters
TC828A-1 5/1/00
DETAILED DESCRIPTION
The TC828A charge pump converter inverts the voltage
applied to the VIN pin. Conversion consists of a two-phase
operation (Figure 1). During the first phase, switches S2 and
S4 are open and S1 and S3 are closed. During this time, C1
charges to the voltage on VIN and load current is supplied
from C2. During the second phase, S2 and S4 are closed,
and S1 and S3 are open. This action connects C1 across
C2, restoring charge to C2.
APPLICATIONS INFORMATION
Output Voltage Considerations
The TC828A performs voltage conversion but does not
provide
regulation. The output voltage will droop in a linear
manner with respect to load current. The value of this
equivalent output resistance is approximately 25
nominal
at +25
°C and VIN = +5V. VOUT is approximately – 5V at light
loads, and droops according to the equation below:
VDROOP = IOUT x ROUT
VOUT = – (VIN – VDROOP)
Charge Pump Efficiency
The overall power efficiency of the charge pump is
affected by four factors:
(1) Losses from power consumed by the internal oscil-
lator, switch drive, etc. (which vary with input volt-
age, temperature and oscillator frequency).
(2) I
2R losses due to the on-resistance of the MOSFET
switches on-board the charge pump.
(3) Charge pump capacitor losses due to effective
series resistance (ESR).
Figure 1. Ideal Switched Capacitor Charge Pump
(4) Losses that occur during charge transfer (from the
commutation capacitor to the output capacitor)
when a voltage difference between the two capaci-
tors exists.
Most of the conversion losses are due to factors (2), (3)
and (4) above. These losses are given by Equation 1.
PLOSS (2, 3, 4) = IOUT
2 x ROUT
IOUT2 x
[ 1 +8RSWITCH+ 4ESRC1+ ESRC2 ]
(fOSC) C1
The 1/(fOSC)(C1) term in Equation 1 is the effective
output resistance of an ideal switched capacitor circuit
(Figures 2a, 2b).
The
losses in the circuit
due to factor (4) above
are also shown in Equation 2. The output voltage ripple is
given by Equation 3.
PLOSS (4) =
[(0.5)(C1)(VIN2– VOUT2) + (0.5)(C2)(VRIPPLE2
– 2VOUTVRIPPLE)
] x f
OSC
VRIPPLE =
IOUT
+2(IOUT)(ESRC2)
(fOSC)(C2)
Figure 2a. Ideal Switched Capacitor Model
Figure 2b. Equivalent Output Resistance
VOUT = – (VIN)
C1
C2
TC828
IN
S1
S3
S4
S2
V+
V
OUT
R
L
C1
C2
f
V+
V
OUT
R
EQUIV
R
EQUIV =
R
L
C2
f x C1
1
Equation 2.
Equation 1.
Equation 3.
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相关代理商/技术参数 |
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|---|---|
| TC828AECTTR | 功能描述:电荷泵 Switched Capacitor RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
| TC828FR | 制造商:Thomas & Betts 功能描述:CABLE TIES |
| TC-828-SC | 制造商:Thomas & Betts 功能描述: |
| TC828TB | 制造商:Thomas & Betts 功能描述:Cable Accessories Four Way Mounting Base Nylon Natural Bulk |
| TC828-TB | 制造商:Thomas & Betts 功能描述:Mount, Cable Tie; 0.39" x 0.875"; #8 screw; 0.19" tie W; Nylon 6.6 制造商:Thomas & Betts 功能描述:MOUNTING BASE, 0.19", NYLON 6.6, CABLE TIE 50LBS; Mount Fixing Type:Screw; Mount Material:Nylon 6.6; Mount Color:Natural; Accessory Type:Mounting Base; For Use With:Cable Ties Up to 50lbs ;RoHS Compliant: Yes 制造商:Thomas & Betts 功能描述:Cable Accessories Four Way Mounting Base Nylon Natural Bulk |
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