Miniature Transformerless Power Circuit

Hello,

using a AC to DC IC

Using the products of Powerint or Similar, i wish the following:-

OUTPUT To power a GSM module working

DC volt [url removed, login to view] - [url removed, login to view] (see notes 3.2) & I will also need a version for [url removed, login to view] - [url removed, login to view] 2amps (may need to use a different module)

2amps

The reason i wish to use the Powerint products is there miniature size and stability of the products. I have looked into using a bridge rectifier + Regulator and found that the end result is too big!

Input

AC 240v

20+Amp

50hz

Working off UK mains electricity

Module POWER Requirements TC35i

BEWARE I MAY NEED TO TEST THE FINAL SOLUTION VIA AN oscilloscope! So be sure that your solution can meet the standards.

The circuit also must offer some form of regulated voltage so it does not destroy the components if a surge occurs & the voltage must also be maintained via capacitors and not allowed to drop below [url removed, login to view]

I have attached a File that represents a Linear Regulator, this circuit although provides a solution does not meet the size requirement!

Please try to use parts that can be sourced from [url removed, login to view]

3.2 Power supply

The power supply of the GSM engine has to be a single voltage source in the range of

VBATT+ = 3.3V...4.8V. It must be able to withstand a sufficient current in a transmission burst

which typically rises to 2A (see Chapter 5.4.1). Beyond that, the power supply must be able

to account for increased current consumption if the module is exposed to inappropriate

conditions, for example antenna mismatch.

5

## Deliverables

Module POWER Requirements TC35i

3.2 Power supply

The power supply of the GSM engine has to be a single voltage source in the range of

VBATT+ = 3.3V...4.8V. It must be able to withstand a sufficient current in a transmission burst

which typically rises to 2A (see Chapter 5.4.1). Beyond that, the power supply must be able

to account for increased current consumption if the module is exposed to inappropriate

conditions, for example antenna mismatch.

5 BATT+ pins and 5 GND pins are available on the ZIF connector. The RF power amplifier is

driven directly from BATT+.

All the key functions for supplying power to the GSM engine are handled by an ASIC power

supply. The ASIC provides the following features:

__ Stabilizes the supply voltages for the GSM baseband processor and for the RF part

using linear voltage regulators.

__ Controls the module's power up and power down procedures.

__ A watchdog logic implemented in the baseband processor periodically sends signals to

the ASIC, allowing it to maintain the supply voltage for all TC35i components. Whenever

the watchdog pulses fail to arrive constantly, the module is turned off.

__ Controls the charging circuit

__ Delivers a regulated voltage of [url removed, login to view] across the VDD pin. The output voltage VDD may

be used to supply your application, for example, an external LED or level shifter.

However, the external circuitry must not cause any spikes or glitches on voltage VDD.

This voltage is not available in POWER DOWN mode. Therefore, the VDD pin can be

used to indicate whether or not TC35i is in POWER DOWN mode.

__ Provides power to the SIM interface.

Please refer to Table 3 for a description of the power supply pins and their electrical

specifications.

TC35i Hardware Interface Description

Confidential / Released s mo b i l e

[url removed, login to view] Page 24 of 86 [url removed, login to view]

3.2.1 Power supply pins on the ZIF connector

10 pins of the ZIF connector are dedicated to connect the supply voltage (BATT+) and

ground (GND). The values stated below must be measured directly at the reference points

on the TC35i board (BATT+ pad and GND pad as shown in Figure 34).

The POWER pins signalize a connected charger to the module and serve as current input

for charging of a Li-Ion battery.

VDDLP can be used to back up the RTC.

Table 3: Power supply pins of ZIF connector

Signal name Pin I/O Description Parameter

BATT+ 1-5 I/O Positive operating voltage 3.3 V...4.8 V, Ityp ~2 A during transmit

burst (see Chapter 5.4.1)

The minimum operating voltage should

never fall below 3.3 V, not even in case

of voltage drop.

GND 6-10 X Ground 0 V

POWER 11-12 I Positive charging voltage Imax = 500 mA (provided by external

source, e.g. charger)

U = 5.5...8 V recommended

internal Pull Down R=100k_

VDDLP 30 I/O Buffering of RTC (see

Chapter 3.3.1.4)

UOUT,max = VBATT+

UIN = 2.0 V...5.5 V

Ri = 1k_

Iin,max = 30?A

TC35i Hardware Interface Description

Confidential / Released s mo b i l e

[url removed, login to view] Page 25 of 86 [url removed, login to view]

3.2.2 Minimizing power losses

When designing the power supply for your application please pay specific attention to power

losses. Ensure that the input voltage measured on the TC35i never drops below the

specified minimum ([url removed, login to view] at BATT+), not even in a transmit burst where current consumption

can rise to typical peaks of 2A at BATT+. It should be noted that TC35i switches off when

exceeding these limits. Any voltage drops that may occur in a transmit burst should not

exceed 400mV. For further details see Chapter 5.4.

Note: In order to minimize power losses, use a FFC cable as short as possible. The

resistance of the power supply lines on the host board and a battery pack should

also be considered.

Example: The ZIF-FFC-ZIF connection causes a resistance of 50mO in the BATT+ line and

50mO in the GND line, if the FFC reaches the maximum length of 200mm. As a

result, a 2A transmit burst would add up to a total voltage drop of 200mV. In

addition, if a battery pack is involved, further losses may occur due to the

resistance across the battery lines.

Figure 3: Power supply limits during transmit burst

The input voltage VBATT+ must be measured directly at the test pads on the TC35i board. For

detailed information see Figure 34.

3.2.3 Monitoring power supply

To help you monitor the supply voltage you can use the AT^SBV command which returns the

voltage measured at reference points BATT+ pad and GND pad.

The voltage is continuously measured at intervals depending on the operating mode on the

RF interface. The duration of measuring ranges from [url removed, login to view] in TALK/DATA mode up to 50s

when the module is in IDLE mode or Limited Service (deregistered). The displayed voltage

(in mV) is averaged over the last measuring period before the AT^SBV command was

executed.

For details please refer to [1]

Electronics

Project ID: #3255789

About the project