MC33560DW データシートの表示（PDF） - ON Semiconductor

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MC33560DW

Power Management and Interface IC for Smartcard Readers and Couplers

ON Semiconductor 

MC33560

The card detector has an internal 50 ms debouncing delay.

The micro controller has to insert an additional delay (in the

ms range) to allow the card contacts to stabilize in the card

connector before setting PWRON = H.

When the card detector circuit detects a card extraction, it

activates the powerdown sequence and stops the converter,

regardless of the PWRON signal. The 50 ms delay of the

debouncer is enough to ensure that all card signals have

reached a safe value before communication with the card

takes place.

CARD STATUS

The controlling microprocessor is informed of the

MC33560 status by interrupt and by polling. When a card is

extracted or inserted, the INT line is asserted low. The

interrupt is cleared upon the rising edge of CS or upon the

rising edge of PWRON (INT line set to high state).

The microprocessor can poll the status at any time by

reading the RDYMOD pin with proper PWRON setting

(see Tables 2 and 4).

Since INT and RDYMOD have a high value pullup

resistor (240 kW typical), their rise time can be as long as

10 ms if parasitic capacitance is high and no other pullup

circuitry is connected.

POWER MANAGER

The task of the power manager is to activate only those

circuit functions which are needed for a determined operating

mode in order to minimize power consumption (Figure 19).

In standby mode (PWRON = L) the power manager keeps

only the “card present” detector alive. All card interface pins

are forced to ground potential.

In the event of a powerup request from the microcontroller

(PWRON L to H transition, CS = L) the power manager

starts the DC−DC converter. As soon as the CRDVCC

supply reaches the operating voltage range, the circuit

activates the card signals in the following sequence:

CRDVCC, CRDIO, CRDCLK, CRDC4/C8, CRDRST

At the end of the transaction (PWRON reset to L, CS = L)

or forced card extraction, the CRDVCC supply powers

down and the card signal deactivation sequence takes place:

CRDRST, CRDC4/C8, CRDCLK, CRDIO, CRDVCC

When CS = L, the bi−directional signal lines (I/O, C4 and

C8) are put into high impedance state to avoid signal

collision with the microcontroller in transmission mode.

BATTERY UNDERVOLTAGE DETECTOR

The task of this block is to monitor the supply voltage, and

to allow operation of the DC−DC converter only with valid

voltage (typically 1.5 V). The comparator has been designed

to have stability better than 20 mV in the temperature range.

DC−DC CONVERTER

Upon request from the power manager, the DC−DC

converter generates the CRDVCC supply for the smartcard.

The output voltage is programmable for 3.0 V or 5.0 V (see

Table 3) to guarantee full cross compatibility of the reader

for 5.0 V and 3.0 V smartcards. The wide voltage supply

range, 1.8 V < VBAT < 6.6 V, accommodates a broad range

of coupler applications with different battery configurations

(single cell or multiple cells, serial or parallel connections).

The CRDVCC is current−limited and short−circuit−proof.

To avoid excessive battery loading during a card

short−circuit, a current integration function forces the

powerdown sequence (Figure 28). To retry the session, the

microprocessor works through the power on sequence as

defined in the power manager section.

DC−DC CONVERTER OPERATING PRINCIPLES

The DC−DC converter architecture used in the MC33560

allows step−up and step−down voltage conversion to be

done. The unique regulation architecture permits an

automatic transition from step−up to step−down, and from

zero to full load, without affecting the output characteristics.

DC−DC Converter Description: The converter

architecture is very similar to the boost architecture, with an

active rectifier in place of the diode. The switching transistor

is connected to ground through a resistor network in order to

adjust the maximum peak current (Figure 22). A transistor

connected to the converter output (CRDVCC) forces this pin

to a low voltage when the converter is not operating. This

prevents erratic voltage supply to the smartcard when not

in use.

The MC33560 has a built in oscillator; the DC−DC

converter requires only one inductor and the output filtering

capacitor to operate.

Stepup Operation: When the card supply voltage is

lower than the battery voltage, the converter operates like a

boost converter; the active rectifier behavior is similar to

that of a diode.

Stepdown Operation: When the card supply voltage is

higher than the battery voltage, the rectifier control circuit

puts the power rectifying transistor in conduction when the

L1 voltage reaches VBAT + VFSAT22. The voltage across the

rectifying transistor is higher than in step−up operation. The

efficiency is lower, and similar to a linear regulator.

Fault Detection: The DC−DC converter has several

features that help to avoid electrical overstress of the

MC33560 and of the smartcard, and help to ensure that data

transmission with the smartcard occurs only when its supply

voltage is within predetermined limits. These functions are:

• Overtemperature Detection,

• Current Limitation, and

• Card Supply Undervoltage Detection.

The level at which current will be limited is defined by the

maximum card supply current programmed with the

external components L1 and RLIM.

The undervoltage detection levels for 3.0 V and 5.0 V card

supply are preset internally to the MC33560.

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