MAX6952EVKIT 데이터 시트보기 (PDF) - Maxim Integrated

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MAX6952EVKIT

MAX6952 Evaluation Kit

Maxim Integrated 

MAX6952 Evaluation Kit

5 x 7 LED matrix displays are cathode-row type. The

user must provide the EV kit with a DC power supply

capable of supplying between 2.7V and 5.5V and

capable of providing at least 500mA.

The EV kit connects to a compatible PC parallel port to

control the EV kit. The EV kit’s SPI-compatible serial

interface is connected to a MAX1841 (U3) and two

MAX3370 (U4, U6) level translators. The translators

level shift the computer’s parallel port logic 5V signals

to the EV kit’s logic VCC voltage level chosen by the

user. The translators can function with voltages down to

2.7V. The level translators’ parallel port side is powered

by the parallel port’s D5–D7 data pins, diodes D9/D10,

and capacitor C2, which provides approximately 5V to

the translators’ power input. The power supply connect-

ed to VCC provides power to the translators’ outputs. A

6-pin header (J2) is provided for monitoring the 5V

CLK_P, CS_P, DIN_P, DOUT_P non-level-translated

and loopback signals coming from the parallel port

cable.

The EV kit can be reconfigured for standalone opera-

tion and connected to an external microcontroller for

evaluation. Pullup resistors R1–R4 and R10 are provid-

ed on the EV kit for the MAX6952’s CLK, CS, DIN,

DOUT, and BLINK pins. PCB pads are provided for

interfacing or monitoring the CLK, CS, DIN, DOUT, and

BLINK level-translated pins of the MAX6952 ICs.

The MAX6952 ICs are configured for an external 4MHz

oscillator provided by IC U5, ceramic resonator (Y1),

and resistors R8 and R7. Resistor R7 provides positive

feedback to the inverter’s input (U5-A) and damping

resistor R8 provides attenuated coupling between the

feedback circuit and inverter. Inverters U5-B and U5-C

provide buffering and sharpen the clock signal. The EV

kit can be reconfigured for evaluating other frequencies

by applying an external TTL/CMOS-compatible clock to

BNC connector EXT_CLK and reconfiguring jumper

JU9. The external clock’s frequency range should be

within 1MHz to 8MHz.

Both MAX6952’s (U1, U2) blink signals can be moni-

tored with an oscilloscope at test points TP1 and TP2,

respectively. Each MAX6952’s peak segment current is

set to 30mA by resistors R5 and R6 for U1 and U2,

respectively.

The parallel port signals are level translated and

buffered from the EV kit by the level translators.

However, the two sides are not galvanically isolated.

Figure 4 shows the parallel port and level-translation

interface for the MAX6952 EV kit.

Jumper Selection

Standalone Configuration

The MAX6952 EV kit features several jumpers (JU1–

JU8) to reconfigure the EV kit for standalone operation

mode or PC/software control mode. Tables 1 and 2 list

the jumpers to cut open or short for the desired evalua-

tion mode. Note: All jumpers must be configured for

only one mode at a time. A suitable voltage must be

selected for standalone mode. Configure all jumpers for

either standalone or PC/software control mode.

Evaluating Other Oscillator Frequencies

The MAX6952 EV kit features a jumper to select the mul-

tiplex clock source. The MAX6952 EV kit is configured to

be driven at 4MHz by an external oscillator formed by

ceramic resonator Y1, resistors R7/R8, and inverter U5.

The user can connect an external TTL/CMOS clock

oscillator to the EXT_CLK pad to evaluate other frequen-

cies (1MHz (min) to 8MHz (max)). The 3-pin jumper JU9

selects the source for the MAX6952 multiplex clock.

Table 3 lists the various jumper options.

Troubleshooting

Problem: Cannot find MAX6952 EV kit parallel port

connection.

Ensure that the I/O extension cable is connected to a

parallel port, and not a SCSI or other type of port. Verify

that the supplied LPTCON.VXD is in the same directory

as MAX6952.EXE. If a local printer driver is installed,

temporarily disable it. The software does not work if the

program icon is dragged onto the windows desktop;

instead, install the software using the install program.

Table 3. Jumper JU9 Functions

SHUNT

LOCATION

OSCILLATOR

SOURCE

OSCILLATOR

FREQUENCY

1 and 2

Inverter U5-C

4MHz, set by EV kit

oscillator

2 and 3

EXT_CLK pad,

D11, and U5-F

provide VCC level

clock

External TTL/CMOS

clock range (1MHz to

8MHz) for the external

oscillator

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