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产品型号LMC7660IN的概述

芯片 LMC7660IN 的概述 LMC7660IN 是一款广泛应用于电压转换的集成电路，特别是在将正电压转换为负电压的场合。该芯片具有高效率和简单的外部组件要求，因此在多种电子设备中成为了关键的电源管理部件。由于其独特的设计，LMC7660IN 可以将输入电压翻转，同时保持较低的功耗。这使其在便携式设备、音频设备以及各种需要双极性电源的应用中得到了普遍采用。芯片 LMC7660IN 的详细参数 LMC7660IN 的主要技术参数如下： - 输入电压范围：2V 至 12V - 输出电压：-Vout 反相，输出电压接近于输入电压的反相值 - 输出电流：最小值为 10mA，最大值可达 20mA - 功耗：典型情况下，工作电流为 300μA - 频率响应：典型开关频率为 10kHz - 温度范围：工作温度范围为 -40℃ 至 +85℃ - 封装类型：DIP（双列直插封装）芯片 LMC7...

产品型号LMC7660IN的Datasheet PDF文件预览

April 1997

LMC7660

Switched Capacitor Voltage Converter

General Description

The LMC7660 is a CMOS voltage converter capable of con-

verting a positive voltage in the range of +1.5V to +10V to

the corresponding negative voltage of −1.5V to −10V. The

Features

n Operation over full temperature and voltage range

without an external diode

n Low supply current, 200 µA max

n Pin-for-pin replacement for the 7660

n Wide operating range 1.5V to 10V

n 97% Voltage Conversion Efficiency

n 95% Power Conversion Efficiency

n Easy to use, only 2 external components

n Extended temperature range

LMC7660 is

pin-for-pin replacement for the

industry-standard 7660. The converter features: operation

over full temperature and voltage range without need for an

external diode, low quiescent current, and high power effi-

ciency.

The LMC7660 uses its built-in oscillator to switch 4 power

MOS switches and charge two inexpensive electrolytic ca-

pacitors.

n Narrow SO-8 Package

Block Diagram

DS009136-1

Pin Configuration

DS009136-2

Ordering Information

Package

Temperature Range

Industrial

NSC

Drawing

−40˚C to +85˚C

LMC7660IN

8-Lead Molded DIP

N08E

M08A

8-Lead Molded Small Outline

LMC7660IM

DS009136

www.national.com

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

Power Dissipation (Note 3)

Dual-In-Line Package

Surface-Mount Package

T_JMax (Note 3)

1.4W

0.6W

150˚C

θ_JA(Note 3)

Supply Voltage

Input Voltage on Pin 6, 7

(Note 2)

10.5V

Dual-In-Line Package

Surface-Mount Package

Storage Temp. Range

Lead Temperature

90˚C/W

160˚C/W

−0.3V to (V⁺+ 0.3V)

for V⁺5.5V

−65˚C ≤ T ≤ 150˚C

(V⁺− 5.5V) to (V⁺+ 0.3V)

for V⁺5.5V

(Soldering, 5 sec.)

260˚C

ESD Tolerance (Note 7)

2000V

Current into Pin 6 (Note 2)

20 µA

Output Short Circuit

Duration (V⁺≤ 5.5V)

Continuous

Electrical Characteristics (Note 4)

LMC7660IN/

LMC7660IM

Limit

Units

Symbol

Parameter

Conditions

Typ

Limits

(Note 5)

200

= ∞

I_s

Supply Current

R_L

120

µA

max

400

V⁺H

V⁺L

R_out

Supply Voltage

Range High (Note 6)

Supply Voltage

Range Low

R_L10 kΩ, Pin 6 Open

Voltage Efficiency ≥ 90%

3 to 10

1.5 to 3.5

3 to 10

1.5 to 3.5

100

R_L10 kΩ, Pin 6 to Gnd.

Voltage Efficiency ≥ 90%

Output Source

Resistance

I_L20 mA

Ω

120

max

Ω

2V, I_L3 mA

110

200

Pin 6 Short to Gnd.

300

max

kHz

F_osc

Oscillator

Frequency

P_eff

Power Efficiency

R_L5 kΩ

min

= ∞

V_{o eff}

Voltage Conversion

Efficiency

R_L

99.9

min

µA

Pin 7 Gnd. or V

I_osc

Oscillator Sink or

Source Current

Note 1: Absolute Maximum ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating

the device beyond its rated operating conditions. See Note 4 for conditions.

Note 2: Connecting any input terminal to voltages greater than V or less than ground may cause destructive latchup. It is recommended that no inputs from sources

operating from external supplies be applied prior to “power-up” of the LMC7660.

Note 3: For operation at elevated temperature, these devices must be derated based on a thermal resistance of θ and T max, T

+ θ

P .

0, and apply for the LMC7660 unless otherwise

osc

5V, C

Note 4: Boldface numbers apply at temperature extremes. All other numbers apply at T

25˚C, V

specified. Test circuit is shown in Figure 1 .

Note 5: Limits at room temperature are guaranteed and 100% production tested. Limits in boldface are guaranteed over the operating temperature range (but not

100% tested), and are not used to calculate outgoing quality levels.

Note 6: The LMC7660 can operate without an external diode over the full temperature and voltage range. The LMC7660 can also be used with the external diode

Dx, when replacing previous 7660 designs.

Note 7: The test circuit consists of the human body model of 100 pF in series with 1500Ω.

www.national.com

Electrical Characteristics (Note 4) (Continued)

DS009136-5

FIGURE 1. LMC7660 Test Circuit

Typical Performance Characteristics

OSC Freq. vs OSC

Capacitance

V_outvs I_out

DS009136-19

DS009136-20

DS009136-18

Supply Current & Power Efficiency

Output Source Resistiance as a

Function of Temperature

vs Load Current (V⁺2V)

vs Load Current (V⁺5V)

DS009136-21

DS009136-22

DS009136-23

www.national.com

Typical Performance Characteristics (Continued)

Unloaded Oscillator Frequency

as a Function of Temperature

Output R vs Supply Voltage

P_effvs OSC Freq.

DS009136-26

DS009136-25

DS009136-24

The LMC7660 closely approaches 1 and 2 above. By using

a large pump capacitor C_p, the charge removed while sup-

plying the reservoir capacitor is small compared to C_p’s total

charge. Small removed charge means small changes in the

pump capacitor voltage, and thus small energy loss and high

efficiency. The energy loss by C_pis:

Application Information

Circuit Description

The LMC7660 contains four large CMOS switches which are

switched in a sequence to provide supply inversion V_out

−V_in. Energy transfer and storage are provided by two inex-

pensive electrolytic capacitors. Figure 2 shows how the

LMC7660 can be used to generate −V⁺from V⁺. When

switches S1 and S3 are closed, C_pcharges to the supply

voltage V⁺. During this time interval, switches S2 and S4 are

open. After C_pcharges to V⁺, S1 and S3 are opened, S2 and

S4 are then closed. By connecting S2 to ground, C_pdevel-

ops a voltage −V⁺/2 on C_r. After a number of cycles C_rwill be

pumped to exactly −V⁺. This transfer will be exact assuming

no load on C_r, and no loss in the switches.

By using a large reservoir capacitor, the output ripple can be

reduced to an acceptable level. For example, if the load cur-

rent is 5 mA and the accepted ripple is 200 mV, then the res-

ervoir capacitor can omit approximately be calculated from:

In the circuit of Figure 2, S1 is a P-channel device and S2,

S3, and S4 are N-channel devices. Because the output is bi-

ased below ground, it is important that the p⁻wells of S3 and

S4 never become forward biased with respect to either their

sources or drains. A substrate logic circuit guarantees that

these p⁻wells are always held at the proper voltage. Under

all conditions S4 p⁻well must be at the lowest potential in the

Precautions

1. Do not exceed the maximum supply voltage or junction

temperature.

circuit. To switch off S4, a level translator generates V_GS4

2. Do not short pin 6 (LV terminal) to ground for supply volt-

ages greater than 3.5V.

3. Do not short circuit the output to V⁺.

0V, and this is accomplished by biasing the level translator

from the S4 p⁻well.

An internal RC oscillator and 2 circuit provide timing sig-

4. External electrolytic capacitors C_rand C_pshould have

their polarities connected as shown in Figure 1.

nals to the level translator. The built-in regulator biases the

oscillator and divider to reduce power dissipation on high

supply voltage. The regulator becomes active at about V⁺

Replacing Previous 7660 Designs

6.5V. Low voltage operation can be improved if the LV pin is

shorted to ground for V⁺≤ 3.5V. For V⁺≥ 3.5V, the LV pin

must be left open to prevent damage to the part.

To prevent destructive latchup, previous 7660 designs re-

quire a diode in series with the output when operated at el-

evated temperature or supply voltage. Although this pre-

vented the latchup problem of these designs, it lowered the

available output voltage and increased the output series re-

sistance.

Power Efficiency and Ripple

It is theoretically possible to approach 100% efficiency if the

following conditions are met:

The National LMC7660 has been designed to solve the in-

herent latch problem. The LCM7660 can operate over the

entire supply voltage and temperature range without the

need for an output diode. When replacing existing designs,

the LMC7660 can be operated with diode Dx.

1. The drive circuitry consumes little power.

2. The power switches are matched and have low R_on

3. The impedance of the reservoir and pump capacitors are

negligibly small at the pumping frequency.

www.national.com

Application Information (Continued)

DS009136-6

FIGURE 2. Idealized Voltage Converter

current cause an increased impedance of C_rand C_p. The in-

creased impedance, due to a lower switching rate, can be

offset by raising C_rand C_puntil ripple and load current re-

quirements are met.

Typical Applications

Changing Oscillator Frequency

It is possible to dramatically reduce the quiescent operating

current of the LMC7660 by lowering the oscillator frequency.

The oscillator frequency can be lowered from a nominal 10

kHz to several hundred hertz, by adding a slow-down ca-

pacitor C_osc(Figure 3). As shown in the Typical Performance

Curves the supply current can be lowered to the 10 µA

range. This low current drain can be extremely useful when

used in µPower and battery back-up equipment. It must be

understood that the lower operating frequency and supply

Synchronizing to an External Clock

Figure 4 shows an LMC7660 synchronized to an external

clock. The CMOS gate overrides the internal oscillator when

it is necessary to switch faster or reduce power supply inter-

ference. The external clock still passes through the 2 circuit

in the 7660, so the pumping frequency will be ¹

clock frequency.

⁄ the external

DS009136-7

FIGURE 3. Reduce Supply Current by Lowering Oscillator Frequency

DS009136-8

FIGURE 4. Synchronizing to an External Clock

Lowering Output Impedance

Paralleling two or more LMC7660’s lowers output imped-

ance. Each device must have it’s own pumping capacitor C_p,

but the reservoir capacitor C_ris shared as depicted in Figure

5. The composite output resistance is:

www.national.com

It is possible to generate −15V from +5V by connecting the

second 7660’s pin 8 to +5V instead of ground as shown in

Figure 7. Note that the second 7660 sees a full 20V and the

input supply should not be increased beyond +5V.

Typical Applications (Continued)

Increasing Output Voltage

Stacking the LMC7660s is an easy way to produce a greater

negative voltage. It should be noted that the input current re-

quired for each stage is twice the load current on that stage

as shown in Figure 6. The effective output resistance is ap-

proximately the sum of the individual R_outvalues, and so

only a few levels of multiplication can be used.

DS009136-9

FIGURE 5. Lowering Output Resistance by Paralleling Devices

DS009136-10

FIGURE 6. Higher Voltage by Cascade

DS009136-11

FIGURE 7. Getting −15V from +5V

Split V⁺In Half

In the

⁄2 cycle when S2 and S4 are closed, the capacitors

switch from a series connection to a parallel connection. This

forces the capacitors to have the same voltage; the charge

redistributes to maintain precisely V⁺/2, across C_pand C_r. In

this application all devices are only V⁺/2, and the supply volt-

Figure 8 is one of the more interesting applications for the

LMC7660. The circuit can be used as a precision voltage di-

vider (for very light loads), alternately it is used to generate a

⁄ supply point in battery applications. In the ⁄ cycle when

age can be raised to 20V giving exactly 10V at V_out

S1 and S3 are closed, the supply voltage divides across the

capacitors in a conventional way proportional to their value.

www.national.com

at V⁺+ (V⁺−V_D1). D1 is reverse biased in this interval. This

application uses only two of the four switches in the 7660.

The other two switches can be put to use in performing a

Typical Applications (Continued)

Getting Up … and Down

negative conversion at the same time as shown in Figure 10.

The LMC7660 can also be used as a positive voltage multi-

plier. This application, shown in Figure 9, requires 2 addi-

In the

⁄2 cycle that D1 is charging C_p1, C_p2 is connected

from ground to −V_outvia S2 and S4, and C_r2 is storing C_p2’s

charge. In the interval that S1 and S3 are closed, C_p1 pumps

the junction of D1 and D2 above V⁺, while C_p2 is refreshed

from V⁺.

tional diodes. During the first

through D1; D2 is reverse biased. In the next

⁄ cycle S2 charges C_p1

⁄2 cycle S2 is

open and S1 is closed. Since C_p1 is charged to V⁺− V_D1and

is referenced to V⁺through S1, the junction of D1 and D2 is

DS009136-12

FIGURE 8. Split V⁺in Half

DS009136-13

FIGURE 9. Positive Voltage Multiplier

DS009136-14

FIGURE 10. Combined Negative Converter and Positive Multiplier

Regulating −V_out

Thermometer Spans 180˚C

Using the combined negative and positive multiplier of Fig-

ure 11 with an LM35 it is possible to make a µPower ther-

mometer that spans a 180˚C temperature range. The LM35

temperature sensor has an output sensitivity of 10 mV/˚C,

while drawing only 50 µA of quiescent current. In order for

the LM35 to measure negative temperatures, a pull down to

a negative voltage is required. Figure 11 shows a thermom-

eter circuit for measuring temperatures from −55˚C to

+125˚C and requiring only two 1.5V cells. End of battery life

can be extended by replacing the up converter diodes with

Schottky’s.

It is possible to regulate the output of the LMC7660 and still

maintain µPower performance. This is done by enclosing the

LMC7660 in a loop with a LP2951. The circuit of Figure 12

will regulate V_outto −5V for I_L10 mA, and V_in6V. For V_in

7V, the output stays in regulation up to I_L25 mA. The er-

ror flag on pin 5 of the LP2951 sets low when the regulated

output at pin 4 drops by about 5%. The LP2951 can be shut-

down by taking pin 3 high; the LMC7660 can be shutdown by

shorting pin 7 and pin 8.

www.national.com

Typical Applications (Continued)

The LP2951 can be reconfigured to an adjustable type regu-

lator, which means the LMC7660 can give a regulated output

from −2.0V to −10V dependent on the resistor ratios R1 and

R2, as shown in Figure 13, V_ref1.235V:

DS009136-15

For lower voltage operation, use Schottky rectifiers

FIGURE 11. µPower Thermometer Spans 180˚C, and Pulls Only 150 µA

DS009136-16

FIGURE 12. Regulated −5V with 200 µA Standby Current

www.national.com

Typical Applications (Continued)

DS009136-17

ref

1.235V

Low voltage operation

FIGURE 13. LMC7660 and LP2951 Make a Negative Adjustable Regulator

www.national.com

Physical Dimensions inches (millimeters)

Molded Small Outline Package (M)

Order Number LMC7660IM

NS Package Number M08A

Molded Dual-In-Line Package (N)

Order Number LMC7660IN

NS Package Number N08E

www.national.com

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DE-

VICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMI-

CONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or sys-

tems which, (a) are intended for surgical implant into

the body, or (b) support or sustain life, and whose fail-

ure to perform when properly used in accordance

with instructions for use provided in the labeling, can

be reasonably expected to result in a significant injury

to the user.

2. A critical component in any component of a life support

device or system whose failure to perform can be rea-

sonably expected to cause the failure of the life support

device or system, or to affect its safety or effectiveness.

National Semiconductor

Corporation

National Semiconductor

Europe

National Semiconductor

Hong Kong Ltd.

National Semiconductor

Japan Ltd.

1111 West Bardin Road

Arlington, TX 76017

Tel: 1(800) 272-9959

Fax: 1(800) 737-7018

Fax: (+49) 0-180-530 85 86

13th Floor, Straight Block,

Ocean Centre, 5 Canton Rd.

Tsimshatsui, Kowloon

Hong Kong

Tel: (852) 2737-1600

Fax: (852) 2736-9960

Tel: 81-043-299-2308

Fax: 81-043-299-2408

Email: cnjwge@tevm2.nsc.com

Deutsch Tel: (+49) 0-180-530 85 85

English Tel: (+49) 0-180-532 78 32

Français Tel: (+49) 0-180-532 93 58

Italiano Tel: (+49) 0-180-534 16 80

www.national.com

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.

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LMC7660IN产品参数

型号:	LMC7660IN
是否无铅：	含铅
是否Rohs认证：	不符合
生命周期：	Obsolete
IHS 制造商：	TEXAS INSTRUMENTS INC
零件包装代码：	DIP
包装说明：	PLASTIC, DIP-8
针数：	8
Reach Compliance Code：	not_compliant
ECCN代码：	EAR99
HTS代码：	8542.39.00.01
Factory Lead Time：	1 week
风险等级：	5.14
Is Samacsys：	N
模拟集成电路 - 其他类型：	SWITCHED CAPACITOR CONVERTER
最大输入电压：	10 V
最小输入电压：	1.5 V
标称输入电压：	5 V
JESD-30 代码：	R-PDIP-T8
JESD-609代码：	e0
长度：	9.817 mm
湿度敏感等级：	1
功能数量：	1
端子数量：	8
最高工作温度：	85 °C
最低工作温度：	-40 °C
最大输出电流：	0.02 A
封装主体材料：	PLASTIC/EPOXY
封装代码：	DIP
封装等效代码：	DIP8,.3
封装形状：	RECTANGULAR
封装形式：	IN-LINE
峰值回流温度（摄氏度）：	NOT SPECIFIED
认证状态：	Not Qualified
座面最大高度：	5.08 mm
子类别：	Other Analog ICs
表面贴装：	NO
切换器配置：	DOUBLER INVERTER
最大切换频率：	10 kHz
技术：	CMOS
温度等级：	INDUSTRIAL
端子面层：	Tin/Lead (Sn/Pb)
端子形式：	THROUGH-HOLE
端子节距：	2.54 mm
端子位置：	DUAL
处于峰值回流温度下的最长时间：	NOT SPECIFIED
宽度：	7.62 mm
Base Number Matches：	1

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