TC962CPA [TELCOM]
HIGH CURRENT CHARGE PUMP DC-TO-DC CONVERTER; 高电流电荷泵DC - DC转换器
| 型号： | TC962CPA |
| 厂家： | 
TELCOM SEMICONDUCTOR, INC |
| 描述： | HIGH CURRENT CHARGE PUMP DC-TO-DC CONVERTER |
| 文件： | 总5页 (文件大小：77K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
4
EVALUATION
KIT
AVAILABLE
TC962
HIGH CURRENT CHARGE PUMP DC-TO-DC CONVERTER
FEATURES
GENERAL DESCRIPTION
■ Pin Compatible With TC7662/ICL7662/SI7661
■ High Output Current ....................................... 80mA
■ No External Diodes Required
■ Wide Operating Range ............................. 3V to 18V
■ Low Output Impedance ............................. 28Ω Typ.
■ No Low Voltage Terminal Required
■ Application Zener On Chip
The TC962 is an advanced version of the industry-
standard 7662 high-voltage DC-to-DC converter. Using
improved design techniques and CMOS construction, the
TC962 can source as much as 8mA versus the 7662’s
20mA capability.
As an inverter, the TC962 can put out voltages as high
as 18V and as low as 3V without the need for external
diodes. The output impedance of the device is a low 28Ω
(with the proper capacitors), voltage conversion efficiency
is 99.9%, and power conversion efficiency is 97%.
The low voltage terminal (pin 6) required in some 7662
applications has been eliminated. Grounding this terminal
will double the oscillator frequency from 12kHz to 24kHz.
This will allow the use of smaller capacitors for the same
output current and ripple, in most applications. Only two
external capacitors are required for inverter applications. In
the event an external clock is needed to drive the TC962
(such as paralleling), driving this pin directly will cause the
internal oscillator to sync to the external clock.
■ OSC Frequency Doubling Pin Option for Smaller
Output Capacitors
PIN CONFIGURATIONS (DIP and SOIC)
ORDERING INFORMATION
Part No.
Package
Temp. Range
TC962COE
TC962CPA
TC962EPA
TC962IJA
16-Pin SOIC Wide
8-Pin Plastic DIP
8-Pin Plastic DIP
8-Pin CerDIP
0°C to +70°C
0°C to +70°C
– 40°C to +85°C
– 25°C to +85°C
– 55°C to +125°C
TC962MJA
TC7660EV
8-Pin CerDIP
Evaluation Kit for Charge Pump Family
FUNCTIONAL BLOCK DIAGRAM
8
V
DD
6
I
I
FREQ X 2
TC962
–
7
OSC/C
TIMING
LEVEL
SHIFT
P SW1
N SW4
Q
2
+
+
–
F/F
CAP
C
Q
LEVEL
SHIFT
+
C
P
EXTERNAL
COMPARATOR
WITH HYSTERESIS
GND
3
1
ZENER
CATHODE
V
REF
6.4V
+
OUT
C
R
EXT
LEVEL
SHIFT
N SW2
N SW3
4
–
CAP
R
L
LEVEL
SHIFT
5
V
OUT
TC962-8 9/16/96
TELCOM SEMICONDUCTOR, INC.
4-37
HIGH CURRENT CHARGE PUMP
DC-TO-DC CONVERTER
TC962
Package Power Dissipation (TA ≤ 70°C)
Pin1,whichisusedasatestpinonthe7662,isavoltage
SOIC ...............................................................760mW
PDIP ...............................................................730mW
CerDIP ............................................................800mW
Package Thermal Resistance
referencezenerontheTC962.Thiszener(6.4Vat5mA)has
a dynamic impedance of 12Ω and is intended for use where
the TC962 is supplying current to external regulator circuitry
and a reference is needed for the regulator circuit. (See
applications section.)
The TC962 is compatible with the LTC1044, SI7661,
and ICL7662. It should be used in designs that require
greater power and/or less input to output voltage drop. It
offers superior performance over the ICL7660S.
CerDIP, RθJ-A ................................................ 90°C/W
PDIP, RθJ-A ................................................. 140°C/W
*Static-sensitive device. Unused devices must be stored in conductive
material. Protect devices from static discharge and static fields. Stresses
above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. These are stress ratings only and functional
operation of the device at these or any other conditions above those
indicated in the operational sections of the specifications is not implied.
Exposure to Absolute Maximum Rating Conditions for extended periods
may affect device reliability.
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage (VDD to GND) .................................. +18V
Input Voltage Any Pin............... (VDD + 0.3) to (VSS – 0.3)
Current Into Any Pin .................................................10mA
ESD Protection..................................................... ±2000V
Output Short Circuit................. Continuous (at 5.5V Input)
Storage Temperature Range ................ – 65°C to +150°C
Lead Temperature (Soldering, 10 sec) ................. +300°C
Operating Temperature Range
CPA, COE ............................................. 0°C to +70°C
IJA .................................................... – 25°C to +85°C
EPA .................................................. – 40°C to +85°C
MJA ................................................ – 55°C to +125°C
ELECTRICAL CHARACTERISTICS: VDD = 15V, TA = +25°C (See Test Circuit), unless otherwise indicated.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Unit
VDD
IS
Supply Voltage
3
18
V
Supply Current
VDD = 15V
RL = ∞
TA = +25°C
—
—
—
—
510
700
µA
0 ≤ TA ≤ +70°C
–55 ≤ TA ≤ +125°C
TA = +25°C
0 ≤ TA < +70°C
–55 ≤ TA ≤ +125°C
560
650
190
210
210
µA
µA
µA
µA
µA
VDD = 5V
RO
Output Source
Resistance
IL = 20mA, VDD = 15V
IL = 80mA, VDD = 15V
IL = 3mA, VDD = 5V
—
32
35
—
37
40
50
Ω
Ω
Ω
COSC
PEFF
VDEF
Oscillator Frequency
Power Efficiency
Pin 6 Open
Pin 6 GND
—
93
99
12
24
—
—
—
kHz
kHz
VDD = 15V
RL = 2 kΩ
97
%
Voltage Efficiency
VDD = 15V
99.9
%
RL = ∞
Over Temperature Range
96
6.0
—
—
6.2
12
%
V
VZ
Zener Voltage
IZ = 5mA
6.4
ZZT
Zener Impedance
IL = 2.5mA to 7.5mA
Ω
4-38
TELCOM SEMICONDUCTOR, INC.
HIGH CURRENT CHARGE PUMP
DC-TO-DC CONVERTER
4
TC962
This applies to all types of capacitors, including film
types (polyester, polycarbonate, etc.).
Some applications information suggest that the capaci-
tor is not critical and attribute the limiting factor of the
capacitor to its reactive value. Let's examine this:
APPLICATIONS INFORMATION
Theory of Operation
The TC962 is a capacitive pump (sometimes called a
switched capacitor circuit), where four MOSFET switches
control the charge and discharge of a capacitor.
Thefunctional diagram (page 1) shows how the switch-
ing action works. SW1 and SW2 are turned on simulta-
XC
1
XC =
and ZC =
,
DS
2πf C
where DS (duty cycle) = 50%.
neously, charging CP to the supply voltage, V . This as-
IN
Thus, ZC ≈ 2.6Ω at f = 12kHz, where C = 10µF.
For the TC962, f = 12,000 Hz, and a typical value of C
would be 10µF. This is a reactive impedance of Ϸ 2.6Ω. If
the ESR is as great as 5Ω, the reactive value is not as critical
as it would first appear, as the ESR would predominate.
The 5Ω value is typical of a general-purpose electrolytic
capacitor.
sumes that the on resistance of the MOSFETs in series
with the capacitor results in a charging time (3 time con-
stants) that is less than the on time provided by the oscilla-
tor frequency as shown:
3 (RDS(ON) CP) <CP/(0.5 fOSC
)
In the next cycle, SW1 and SW2 are turned off and
after a very short interval of all switches being off (this
prevents large currents from occurring due to cross con-
duction), SW3 and SW4 are turned on. The charge in CP is
then transferred to CR, BUT WITH THE POLARITY IN-
VERTED. In this way, a negative voltage is now derived.
Page 1 shows a functional diagram of the TC962. An
oscillator supplies pulses to a flip-flop that is then fed to a
set of level shifters. These level shifters then drive each set
of switches at one-half the oscillator frequency.
ESL
C
ESR
Figure 1. Typical Electrolytic Capacitor
Latch Up
AllCMOSstructurescontainaparasiticSCR.Caremust
be taken to prevent any input from going above or below the
supply rail, or latch up will occur. The result of latch up is an
effective short between VDD and VSS. Unless the power
supplyinputhasacurrentlimit, thislatch-upphenomenawill
result in damage to the device. (See Application Note 31 for
additional information.)
The oscillator has two pins that control the frequency of
oscillation. Pin 7 can have a capacitor added that is re-
turned to ground. This will lower the frequency of the
oscillator by adding capacitance to the timing capacitor
internal to the TC962. Grounding pin 6 will turn on
a
current source and double the frequency. This will double
the charge current going into the internal capacitor, as well
as any capacitor added to pin 7.
A zener diode has been added to the TC962 for use as
a reference in building external regulators. This zener runs
from pin 1 to ground.
TEST CIRCUIT
Capacitors
690Ω
In early charge pump converters, the capacitors were
not considered critical due to the high RDS(ON) of the MOS-
FET switches. In order to understand this, let’s look at a
model of a typical electrolytic capacitor (Figure 1).
Note that one of its characteristics is ESR (equivalent
series resistance). This parasitic resistance winds up in
series with the load. Thus, both voltage conversion effi-
ciency and power conversion efficiency are compromised if
a low ESR capacitor is not used.
I
+
S
L
L
V
1
2
8
7
NC
(+5V)
I
+
10µF
C
3
4
R
OSC
C
TC962
C
P
V
5
OUT
(–5V)
10µF
R
+
In the test circuit, for example, just changing two capaci-
tors,CP andCR,fromcapacitorswithunspecifiedESRtolow
ESR-type output, impedance changes from 36Ω to 28Ω, an
improvement of 23%!
TELCOM SEMICONDUCTOR, INC.
4-39
HIGH CURRENT CHARGE PUMP
DC-TO-DC CONVERTER
TC962
TYPICAL APPLICATIONS
+
Combined Negative Converter and Positive Multiplier
Split V In Half
+
V
+
V
1
2
8
7
1
2
8
7
V
D1
V
10µF
+
D2
+
10µF
V
=
3
4
6
5
C
C
OUT
3
4
6
5
TC962
P2
P
TC962
+
+
V
= –V
OUT
2V –2V
D
10µF
+
C
R1
+
10µF
V
2
+
C 1
V
=
P
OUT
+
+
C
10µF
R
Lowering Output Resistance by Paralleling Devices
Positive Voltage Multiplier
+
V
+
V
1
8
8
1
2
1
2
8
7
V
D1
2
3
4
7
6
7
V
10µF
+ 10µF
+
V
=
D2
OUT
C
3
4
6
5
3
4
6
5
C
P2
TC962
TC962
TC962
P1
+
2V –2 V
D
+
+
5
10µF
C
C
P
10µF
P
V
OUT
10µF
C
R
+
4-40
TELCOM SEMICONDUCTOR, INC.
HIGH CURRENT CHARGE PUMP
DC-TO-DC CONVERTER
4
TC962
TYPICAL CHARACTERISTICS
Frequency vs. Temperature
Oscillator Frequency vs. C
Supply Current vs. Temperature
EXT
20
18
16
700
600
T
= +25°C
A
10k
500
400
300
200
+
1k
14
12
10
V
= 15V
100
+
V
= 15V
8
6
100
0
10
–40 –20
0
20 40 60 80 100
–60 –40 –20
0
20 40 60 80 100 120 140
10
100
1000
10,000
–60
120 140
1
CAPACITANCE (pF)
TEMPERATURE (°C)
TEMPERATURE (°C)
Output Resistance vs. Temperature
Current vs. Zener Voltage
Power Conversion Efficiency vs. I
LOAD
150
80
70
T
= +25°C
T
= +25°C
A
50
40
30
20
100
90
A
135
120
EFFICIENCY
60
50
40
80
70
60
+
105
90
V
= 5V I = 3mA
L
SUPPLY
CURRENT
50
75
40
30
20
10
0
60
45
30
15
0
+
30
20
10
V
= 15V I = 20mA
L
10
0
4.5
4.0
ZENER VOLTAGE (V)
8
24 32 40 48 56 64 72 80
LOAD CURRENT (mA)
5.5
6.0
6.5
7.0
16
–60 –40 –20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
Output Resistance vs. Input Voltage
110
100
90
T
= +25°C
A
80
70
60
50
40
30
20
3mA
20mA
10
0
2
4
6
8
10 12 14 16 18 20
INPUT VOLTAGE (V)
TELCOM SEMICONDUCTOR, INC.
4-41
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