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參數(shù)資料
| 型號(hào)： | MAX1721EUT |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Replaced by TMS320VC5506 : Digital Signal Processors 132-BQFP 0 to 0 |
| 中文描述： | SWITCHED CAPACITOR CONVERTER, 200 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | SOT-23, 6 PIN |
| 文件頁(yè)數(shù)： | 6/8頁(yè) |
| 文件大?。?/td> | 568K |
| 代理商： | MAX1721EUT |
M
SOT23, Switched-Capacitor
Voltage Inverters with Shutdown
6
_______________________________________________________________________________________
Charge-Pump Output
The MAX1719/MAX1720/MAX1721 are not voltage reg-
ulators: the charge pumps’ output resistance is
approximately 23
at room temperature (with V
IN
=
+5V), and V
OUT
approaches -5V when lightly loaded.
V
OUT
will droop toward GND as load current increases.
The droop of the negative supply (V
DROOP-
) equals the
current draw from OUT (I
OUT
) times the negative con-
verter’s output resistance (R
O
):
V
DROOP-
= I
OUT
x R
O
The negative output voltage will be:
V
OUT
= -(V
IN
- V
DROOP-
)
Efficiency Considerations
The efficiency of the MAX1719/MAX1720/MAX1721 is
dominated by its quiescent supply current (I
Q
) at low
output current and by its output impedance (R
OUT
) at
higher output current; it is given by:
where the output impedance is roughly approximated
by:
The first term is the effective resistance of an ideal
switched-capacitor circuit (Figures 3a and 3b), and
R
SW
is the sum of the charge pump’s internal switch
resistances (typically 8
to 9
at V
IN
= +5V). The typi-
cal output impedance is more accurately determined
from the
Typical Operating Characteristics
.
Shutdown Mode
The MAX1719/MAX1720/MAX1721 have a logic-con-
trolled shutdown input. Driving
SHDN
low places the
MAX1720/MAX1721 in a low-power shutdown mode.
The MAX1719’s shutdown input is inverted from that of
the MAX1720/MAX1721. Driving SHDN high places the
MAX1719 in a low-power shutdown mode. The charge-
pump switching halts, supply current is reduced to
1nA, and OUT is actively pulled to ground through a 4
resistance.
Applications Information
Capacitor Selection
To maintain the lowest output resistance, use capaci-
tors with low ESR (Table 1). The charge-pump output
resistance is a function of C1’s and C2’s ESR.
Therefore, minimizing the charge-pump capacitor’s
ESR minimizes the total output resistance. Table 2
gives suggested capacitor values for minimizing output
resistance or minimizing capacitor size.
R
1
)
×
f
C1
2R
4ESR
ESR
OUT
OSC
SW
C1
C2
(
+
+
+
η
+
×
V
I
I
I
I
R
OUT
OUT
Q
OUT
OUT
IN
1
S1
IN
S2
S3
S4
C1
C2
V
OUT
= -(V
IN
)
Figure 2. Ideal Voltage Inverter
V+
C1
f
C2
R
L
V
OUT
Figure 3a. Switched-Capacitor Model
R
EQUIV
=
R
EQUIV
V
OUT
R
L
1
V+
f
×
C1
C2
Figure 3b. Equivalent Circuit
NOTE:
( ) CAPACITORS ARE FOR MAX1720.
*ON/OFF POLARITY OF SHDN IS REVERSED FOR MAX1719.
C1
1
μ
F (10
μ
F)
C2
1
μ
F (10
μ
F)
2
1
5
ON
OFF
3
R
L
6
C1+
4
C3
1
μ
F (10
μ
F)
C1-
IN
SHDN
OUT
GND
INPUT
1.5V to 5.5V
NEGATIVE
OUTPUT
-1
·
V
IN
25mA
MAX1719*
MAX1721
Figure 1. Typical Application Circuit
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1720EUT | SOT23, Switched-Capacitor Voltage Inverters with Shutdown |
| MAX1726 | Replaced by TMS320VC5506 : |
| MAX1725EUK-T | 12V, Ultra-Low IQ, Low-Dropout Linear Regulators |
| MAX1725 | Replaced by TMS320VC5506 : Digital Signal Processors 100-LQFP 0 to 0 |
| MAX1725-MAX1726 | Replaced by TMS320VC5506 : |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1721EUT+ | 制造商:Maxim Integrated Products 功能描述:CHG PUMP INV -5.5V TO -1.4V 25MA 6PIN SOT-23 - Rail/Tube |
| MAX1721EUT+T | 功能描述:電荷泵 Switched-Cap Voltage Inverter w/Shutdown RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| MAX1721EUTT | 制造商:MAXIM 功能描述:New |
| MAX1721EUT-T | 功能描述:電荷泵 Switched-Cap Voltage Inverter w/Shutdown RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| MAX1722EUK-T | 制造商:Maxim Integrated Products 功能描述:- Tape and Reel |
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