Download "Improved Start-up Performance for Charge Pumps TPS6030x"

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Power engineering wikipedia, lookup

Electrical substation wikipedia, lookup

Three-phase electric power wikipedia, lookup

Immunity-aware programming wikipedia, lookup

Solar micro-inverter wikipedia, lookup

Ohm's law wikipedia, lookup

Islanding wikipedia, lookup

History of electric power transmission wikipedia, lookup

Pulse-width modulation wikipedia, lookup

Transistor wikipedia, lookup

Power inverter wikipedia, lookup

Current source wikipedia, lookup

Semiconductor device wikipedia, lookup

Variable-frequency drive wikipedia, lookup

Resistive opto-isolator wikipedia, lookup

Integrating ADC wikipedia, lookup

Two-port network wikipedia, lookup

Stray voltage wikipedia, lookup

Rectifier wikipedia, lookup

Schmitt trigger wikipedia, lookup

Surge protector wikipedia, lookup

Power MOSFET wikipedia, lookup

Distribution management system wikipedia, lookup

Alternating current wikipedia, lookup

Voltage regulator wikipedia, lookup

Voltage optimisation wikipedia, lookup

Buck converter wikipedia, lookup

Mains electricity wikipedia, lookup

Switched-mode power supply wikipedia, lookup

Current mirror wikipedia, lookup

Opto-isolator wikipedia, lookup

Transcript
Application Report
SLVA099 - May 2001
Improved Start-Up Performance for Charge Pump
TPS6030x
Thomas Schäffner
Power Management Low Power
ABSTRACT
This document shows a solution to enhance the start-up performance of the TPS603xx
charge pumps. With the circuitry shown, the device can drive at start-up into full load (40 mA).
The TPS603xx charge pumps consist of two charge pump stages that operate in series. The first
one is an unregulated doubler charge pump with its output OUT1. It supplies a second regulated
charge pump which provides 3.3 V or 3 V respectively at OUT2. Therefore, the first charge
pump must be able to provide twice or 1.5 times the output current of the second one, which
works in either a x2 or x1.5 conversion mode. This means that the input voltage of the second
charge pump stage is either doubled or increased by a factor of 1.5.
However, at start-up, the output current of the first charge pump is limited to typically 2 mA until
the output voltage at OUT2 reaches its nominal value. This is because the internal circuits use
the output voltage of OUT2 as supply voltage. At start-up the lower voltage from the input is
used, which limits the start-up performance.
The document shows a solution to enhance the start-up performance. With this circuitry the
device can drive at start-up into full load (40 mA) at OUT1.
NOTE: When OUT1 is loaded with 40 mA, OUT2 must not be loaded.
C1F
1 µF
2
C2F
1 µF
4
8
C1– C1+
3
VIN
CIN
1 µF
C2–
7
C2+
OUT2
VIN
V(OUT2)
C(OUT2)
1 µF
TPS60300/1
OUT1
1
6
VO
C(OUT1)
1 µF
EN
GND
PG
T2
IRLML6302
5
10
R1
1 MΩ
R2
1 MΩ
T1
BC848C
RL
9
Figure 1. Schematic for Improved Start-Up at OUT1
Figure 1 shows the circuit consisting of the TPS6030x charge pump and two external transistors.
The schematic is shown for the open drain power-good version. If the push-pull power good
version is used, R1 must be connected between the power good output and the base of T1. The
value of T1 should then be in the 100 kΩ range.
1
SLVA099
Figure 2 shows the timing diagram for start-up. With the device enabled, the voltage at OUT1
and thereby the voltage at the source pin of T2 rises to about 2 x VI. When the output voltage at
OUT2 reaches its nominal value, the power good output (PG) becomes high and T1 begins to
conduct. T1 pulls the gate of the PMOS transistor T2 to GND, switching on T2 and providing the
output voltage at pin VO. Channel 2 in Figure 2 shows the output current rising immediately to
40 mA. In order to minimize losses, a low VT, low-voltage PMOS transistor (IRLML 6302) has
been used for T2.
VO
I(VO)
V(OUT2)
V(OUT1)
Figure 2. Start-Up Timing
Free samples can be ordered from http://www.ti.com. Type in the complete device name in the
quick search box and select check stock or order under Availability/Samples. To get more
detailed information about the device, see the TPS6030x data sheet (literature number
SLVS302).
2
Improved Start-Up Performance for Charge Pump TPS6030x
IMPORTANT NOTICE
Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its products to the specifications applicable at the time of sale in accordance with
TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary
to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except
those mandated by government requirements.
Customers are responsible for their applications using TI components.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
products or services might be or are used. TI’s publication of information regarding any third party’s products
or services does not constitute TI’s approval, license, warranty or endorsement thereof.
Reproduction of information in TI data books or data sheets is permissible only if reproduction is without
alteration and is accompanied by all associated warranties, conditions, limitations and notices. Representation
or reproduction of this information with alteration voids all warranties provided for an associated TI product or
service, is an unfair and deceptive business practice, and TI is not responsible nor liable for any such use.
Resale of TI’s products or services with statements different from or beyond the parameters stated by TI for
that product or service voids all express and any implied warranties for the associated TI product or service,
is an unfair and deceptive business practice, and TI is not responsible nor liable for any such use.
Also see: Standard Terms and Conditions of Sale for Semiconductor Products. www.ti.com/sc/docs/stdterms.htm
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright  2001, Texas Instruments Incorporated