MAX3387EEUG View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX3387EEUG

3V, ±15kV ESD-Protected, AutoShutdown Plus RS-232 Transceiver for PDAs and Cell Phones

Maxim Integrated 

3V, ±15kV ESD-Protected, AutoShutdown Plus

RS-232 Transceiver for PDAs and Cell Phones

RC

50M to 100M

CHARGE-CURRENT

LIMIT RESISTOR

HIGH-

VOLTAGE

DC

SOURCE

Cs

150pF

RD

330Ω

DISCHARGE

RESISTANCE

STORAGE

CAPACITOR

DEVICE

UNDER

TEST

I

100%

90%

Figure 6a. IEC 1000-4-2 ESD Test Model

IEC 1000-4-2

The IEC 1000-4-2 standard covers ESD testing and

performance of finished equipment; it does not specifi-

cally refer to ICs. The MAX3387E helps you design

equipment that meets Level 4 (the highest level) of IEC

1000-4-2, without the need for additional ESD-protec-

tion components.

The major difference between tests done using the

Human Body Model and IEC 1000-4-2 is higher peak

current in IEC 1000-4-2 because series resistance is

lower in the IEC 1000-4-2 model. Hence, the ESD with-

stand voltage measured to IEC 1000-4-2 is generally

lower than that measured using the Human Body

Model. Figure 6a shows the IEC 1000-4-2 model, and

Figure 6b shows the current waveform for the ±8kV IEC

1000-4-2 Level 4 ESD Contact Discharge test.

The air-gap test involves approaching the device with a

charged probe. The contact-discharge method connects

the probe to the device before the probe is energized.

Machine Model

The Machine Model for ESD tests all pins using a

200pF storage capacitor and zero discharge resis-

tance. Its objective is to emulate the stress caused by

contact that occurs with handling and assembly during

manufacturing. All pins require this protection during

manufacturing, not just RS-232 inputs and outputs.

Therefore, after PC board assembly, the Machine

Model is less relevant to I/O ports.

Applications Information

Capacitor Selection

The capacitor type used for C1–C4 is not critical for

proper operation; polarized or nonpolarized capacitors

can be used. The charge pump requires 0.1µF capaci-

10%

tR = 0.7ns to 1ns

t

30ns

60ns

Figure 6b. IEC 1000-4-2 ESD Generator Current Waveform

Table 2. Minimum Required Capacitor

Values

VCC

C1

C2, C3, C4

(V)

(µF)

(µF)

3.0 to 3.6

0.1

0.1

4.5 to 5.5

0.047

0.33

3.0 to 5.5

0.22

1

tors for 3.3V operation. For other supply voltages, see

Table 2 for required capacitor values. Do not use val-

ues smaller than those listed in Table 2. Increasing the

capacitor values (e.g., by a factor of 2) reduces ripple

on the transmitter outputs and slightly reduces power

consumption. C2, C3, and C4 can be increased without

changing C1’s value. However, do not increase C1

without also increasing the values of C2, C3, and C4 to

maintain the proper ratios (C1 to the other capacitors).

When using the minimum required capacitor values,

make sure the capacitor value does not degrade

excessively with temperature. If in doubt, use capaci-

tors with a larger nominal value. The capacitor’s equiva-

lent series resistance (ESR), which usually rises at low

temperatures, influences the amount of ripple on V+

and V-.

______________________________________________________________________________________ 11

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