MAX14529E Просмотр технического описания (PDF) - Maxim Integrated

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MAX14529E

Overvoltage Protection with USB Charger Detection, LDO, and ESD Protection on D+/D-

Maxim Integrated 

Overvoltage Protection with USB Charger

Detection, LDO, and ESD Protection on D+/D-

Device Operation

The MAX14529E/MAX14530E have an internal oscillator

and charge pump that control the turn-on of the internal

FET switch. The internal oscillator controls the timers

that enable the turn-on of the charge pump and con-

trols the state of the open-drain VOK output. If VIN >

VOVLO, the internal oscillator remains off, thus disabling

the charge pump. If 2.2V < VIN < VOVLO, the internal

charge pump is enabled. The charge-pump turns on

the internal FET switch and asserts VOK. At any time, if

VIN drops below 2.2V or rises above VOVLO, VOK goes

high and the charge pump is disabled, disconnecting

OUT from IN.

Overvoltage Lockout (OVLO)

The MAX14529E has a 5.75V (typ) overvoltage

threshold (OVLO), while the MAX14530E has a 6.8V

(typ) OVLO.

Low Dropout

The low-dropout regulator (LOUT) is powered from

input voltage and supplies 3.3V (typ) to the USB trans-

ceiver. If a lithium-ion (Li+) battery is used to power the

USB transceiver, a boost converter is needed. The LDO

features a minimum 100mA current capability and low

output noise. Drive LEN high to disable the LDO.

Charger Detection

The charger detection detects if there is a short

between the USB D+ and D- data lines. If the data lines

are shorted together and a dedicated charger is

attached, the phone draws more than 500mA to charge

the battery; CDET asserts low. If the data lines are not

biased properly, then an unidentified device is present

and the phone draws no more than 500mA or does not

charge at all, depending on its USB compliance level.

Thermal-Shutdown Protection

The MAX14529E/MAX14530E feature thermal-

shutdown circuitry. The internal switch turns off when

the junction temperature exceeds +150°C (typ) and

immediately goes into a fault mode. The device exits

thermal shutdown after the junction temperature cools

by 20°C (typ).

Applications Information

IN Bypass Capacitor

Bypass IN to GND with a 1µF ceramic capacitor as

close as possible to the device for ±15kV HBM ESD

protection on IN. No capacitor required to obtain ±2kV

HBM protection. If the power source has significant

inductance due to long lead length, take care to

prevent overshoots due to the LC tank circuit and pro-

vide protection.

ESD Test Conditions

ESD performance depends on a number of conditions.

The MAX14529E/MAX14530E are specified for

±15kV HBM typical ESD protection on the D+, D-, and

IN pins when IN is bypassed to ground with a 1µF

ceramic capacitor.

Human Body Model

Figure 2 shows the Human Body Model, and Figure 3

shows the current waveform it generates when dis-

charged into a low impedance. This model consists of

a 100pF capacitor charged to the ESD voltage of inter-

est that is then discharged into the device through a

1.5kΩ resistor.

RC

1MΩ

RD

1500Ω

CHARGE-CURRENT-

LIMIT RESISTOR

DISCHARGE

RESISTANCE

HIGH-

VOLTAGE

DC

SOURCE

Cs

100pF

STORAGE

CAPACITOR

DEVICE

UNDER

TEST

Figure 2. Human Body ESD Test Model

IP 100%

90%

AMPERES

36.8%

10%

0

0 tRL

IR

PEAK-TO-PEAK RINGING

(NOT DRAWN TO SCALE)

TIME

tDL

CURRENT WAVEFORM

Figure 3. Human Body Current Waveform

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