switched capacitor dc-dc converter

[santhoshv78]

I need to design a switched capacitor(no inductor) 1.2V to 3.3V up converter. I am new to this type of design.That would be a great help if anybody give some guidelines to go ahead with the design.
thanks
santosh

 

[kyrandia]

There is a charge pump regulator product of Maxim. can it help you?

/ Warning #1 - Don't waste bandwidt by uploading files already available on the internet.
File delete, use this link instead:
**broken link removed**

 

[leo_o2]

A boot-strap circuit will be a simple choice as well. Only with some capacitors and diodes. Capacitor can keep its voltage constant.

 

[piao]

if you use bootstrap structure, do you think about the output current of the converter, otherwise, I think it is easier to use a charge pump like Dickson charge pump.

Good Luck!

 

[santhoshv78]

The dc-dc converter has to give 30mA of load current. I am looking for a SMPS type of boost converter without the use of inductor.

thanks

 

[andy2000a]

SMPS no inductor ? really ...

who can give me paper talk about it

thank you

 

[andy2000a]

I only find Inductorless Regulated LCD Bias Generator

The MAX868 inverting charge pump provides a low-cost and compact means of generating a regulated negative voltage up to -2 x VIN from a positive input voltage between 1.8V and 5.5V. It uses a pulse-frequency-modulation (PFM) control scheme to generate the regulated negative output voltage. PFM operation is obtained by gating the internal 450kHz oscillator on and off as needed to maintain output voltage regulation. This unique on-demand switching scheme gives the MAX868 excellent light-load efficiency without degrading its full-load operation (up to 30mA), permitting smaller capacitors to take advantage of the oscillator's high switching frequency.

by the way , if we use charge pump for BOOST ckt but how to create
hi-V for MOS switch ?? in 0.25um process IO only 3~5v ..
if we use 3.3 -> 5v ( USB OTG use 20mA ) mos switch need > 5v
I use NMOS for Low Ron ..

 

[minaflying]

you can find a hi-V mos process

 

[ME]

I need to design a switched capacitor(no inductor) 1.2V to 3.3V up converter.

The dc-dc converter has to give 30mA of load current. I am looking for a SMPS type of boost converter without the use of inductor.

I beleive this charge pump (a.k.a. switced capacitor) regulator is what you are looking for, the only problem is that it might have a problem delivering 30mA at a input voltage as low as 1.2V:
But the higher input voltage the more output current it can deliver.
At Vin = 1V it can deliver 10mA, but at Vin = 1.2V it can deliver a little more. Look at the graphs in the datasheet. Remember most of the graphs uses logarithmic scales.

LTC1502-3.3
Single Cell to 3.3V Regulated Charge Pump DC/DC Converter
https://www.linear.com/prod/datasheet.html?datasheet=441

Input Voltage Range: 0.9V to 1.8V
Regulated Output Voltage: 3.3V ±4%
Output Current: 10mA
No Inductors


It's hard to find a charge pump regulator that works at Vin = 1.2V.
Most charge pumps from both Maxim, Linear, Microchip, Analog Devices, NAtional Semiconductors, Texas Instruments, Intersil, Sipex, ON Semiconductors etc. only works at Vin = 1.5V or higher.

 

[ME]

I found some better suited Charge Pumps from Texas Instruments:

TPS60300 and TPS60302
Single-Cell to 3.3V, 20mA Dual Output, High Efficiency Charge Pump
https://focus.ti.com/docs/prod/folders/print/tps60300.html

Topology Boost
Vin (Min) (V) 0.9
Vin (Max) (V) 1.8
Preset Vout (V) 3.3
Iout (A) 0.02
Efficiency (Typ) (%) 85
Iq (Typ) (mA) 0.035
Switching Frequency (Max) (kHz) 650
Package 10VSSOP
Starting Price (1KU) ($) .95


TPS60310 and TPS60312
Single-Cell to 3.3-V, 20-mA Ultra-Low Quiescent Current Charge Pump
https://focus.ti.com/docs/prod/folders/print/tps60310.html

Topology Boost
Vin (Min) (V) 0.9
Vin (Max) (V) 1.8
Preset Vout (V) 3.3
Iout (A) 0.02
Efficiency (Typ) (%) 85
Iq (Typ) (mA) 0.002
Switching Frequency (Max) (kHz) 900
Package 10VSSOP
Starting Price (1KU) ($) 1.05


These IC's has a specified regulated 3.3V ouput current of 20mA @ Vin >1.1V

You should be able to draw 30mA @ Vin = 1.2V (look at figure 5 in the data sheets).

 

[ME]

You could also create your own capacitive step up DC–DC converter like the one shown in this Philips application note:
**broken link removed**

 

[dwang_w]

hi

 

[santhoshv78]

You could also create your own capacitive step up DC–DC converter like the one shown in this Philips application note:
h**p://www.semiconductors.philips.com/acrobat/applicationnotes/AN10218_1.pdf

Thank you all ..Let me try designing this. meanwhile if anybody find any document plz upload.

 

[kiger]

A book about Switched Mode Power Supply

 

[okguy]

A book about Switched Mode Power Supply

Can you re-post the book ?