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ZXGD3103-多口充电器方案骊微

Device Status Package Part

Mark

Reel size (inches) Tape width

(mm) Quantity per reel

ZXGD3103N8TC Production SO8 ZXGD3103

2500

Description

The ZXGD3103 is intended to drive MOSFETS configured as ideal diode replacements. The device is comprised of a differential amplifier detector stage and high current driver. The detector monitors the reverse voltage of the MOSFET such that if body diode conduction occurs a positive voltage is applied to the MOSFET’s Gate pin.

Once the positive voltage is applied to the Gate the MOSFET switches on allowing reverse current flow. The detectors’ output voltage is then proportional to the MOSFET Drain-Source reverse voltage drop and this is applied to the Gate via the driver. This action provides a rapid turn off as current decays. Features

? Proportional Gate Drive

? Turn-off propagation delay 15ns and turn-off time 20ns.

? Detector threshold voltage ~10mV ? Standby current 5mA

? Suitable for Discontinuous Mode (DCM),

Critical Conduction Mode (CrCM) and

Continuous Mode (CCM) operation

? 5-15V V CC range

Applications

? Flyback Converters in:

Adaptors ? LCD Monitors ? Server PSU’s ?

Set Top Boxes

LCD TV

? Resonant Converters ? LED TV

? High power Adaptors ? Street Lighting ?

ATX psu

Pin out details

Typical Configuration

ZXGD

= Product Type Marking Code, Line 1 3103 = Product Type Marking Code, Line 2 YY = Year (ex: 11 = 2011) WW

= Week (01 - 53)

Absolute maximum ratings

Unit

Limit

Parameter Symbol

Supply voltage1V CC 15

to180

Continuous Drain pin voltage1V D -3

GATEH and GATEL output Voltage1V G-3 to V CC + 3 V

Driver peak source current I SOURCE 2.5 A

Driver peak sink current I SINK 6

Reference current I REF 25

Bias voltage V BIAS V CC V

Bias current I BIAS 100

Power dissipation at T A =25°C P D 490

Operating junction temperature T j-40 to +150 °C

Storage temperature T stg-50 to +150 °C

Notes: 1. All voltages are relative to GND pin.

Thermal resistance

Unit

Parameter Symbol

Value

°C/W

Junction to ambient (a) RθJA 255

°C/W

Junction to lead (b) RθlA 120

Notes: a. Mounted on minimum 1oz weight copper on FR4 PCB in still air conditions.

b. Output Drivers - Junction to solder point at end of the lead 5 and 6

ESD Rating

Unit Model Rating

Human Body 2000 V

V Machine 300

ZXGD3103N8

Electrical characteristics at T A = 25°C; V CC = 10V; R BIAS = 3.3k ?; R REF = 4.3k ?

Parameter Symbol Conditions Min. Typ. Max. Unit

Input and supply characteristics Operating current I OP

V D ≤ -200m V - 2.16 - mA

V D ≥ 0V

5.16

Gate Driver Turn-off Threshold Voltage(**)

V T V G = 1V, (*) -16 -10 0 mV GATE output voltage (**)

V G(off)

V D ≥ 0V, (*) - 0.73 1 V

V G

V D = -50mV, (g )

6.0

7.2 - V D = -100mV, (g )

8.8 9.2 - V D ≤ -150mV, (g ) 9.2 9.4

- V D

≤

-200mV, (

g )

9.3 9.5 -

Switching performance (“) for Q G (tot) = 82nC

Turn on Propagation delay t d1

Refer to switching waveforms

in Fig. 3

150

Turn off Propagation delay t d2 15 Gate rise time t r

450

Gate fall time t

Continuous Conduction Mode

Discontinuous Conduction Mode

Notes:

(**) GATEH connected to GATEL (*) R H = 100k ?, R L = O/C (g ) R L = 100k ?, R H = O/C

(“) refer to test circuit below

Schematic Symbol and Pin Out Details

Pin No.

Name Description and function

1 NC No Internal connection

REF

Reference

This pin is connected to V CC via resistor, R REF 3 GATEL

Gate turn off

This pin sinks current, I SINK , from the synchronous MOSFET Gate. 4 GATEH

Gate turn on

This pin sources current, I SOURCE , to the synchronous MOSFET Gate. 5 V CC

Power Supply

This is the supply pin. It is recommended to decouple this point to ground closely with a ceramic capacitor. 6 GND Ground

This is the ground reference point. Connect to the synchronous MOSFET Source

terminal. 7 BIAS

Bias

This pin is connected to V CC via resistor, R BIAS . 8 DRAIN

Drain connection

This pin connects directly to the synchronous MOSFET Drain terminal.

Typical Characteristics

10152025

-5-4-3-2-101

-100

-80

-60-40-200

024********

-100

-80

-60-40-200

46810

-50

-250

255075100125150

10k 100k

100

6810121416182022020406080

100

Gate Current vs Capacitive Load

P e a k C u r r e n t (A )

Capacitance (nF)

Transfer Characteristic

V G G a t e V o l t a g e (V )

V D Drain Voltage (mV)

Transfer Characteristic

G V D Drain Voltage (mV)

Drain Sense Voltage vs Temperature

V D D r a i n V o l t a g e (m V )

Temperature (°C)

Supply Current vs Frequency

S u p p l y C u r r e n t (m A )

Frequency (Hz)

Supply Current vs Capacitive Load Capacitance (nF)

S u p p l y C u r r e n t (m A )

Typical Characteristics

-202468

10-2

2468

-202

46Switch On Speed

V o l t a g e (V )

Time (μs)Switch Off Speed

V o l t a g e (V )

Time (ns)

Gate Drive On Current

G a t e C u r r e n t (A )

Time (μs)Gate Drive Off Current

G a t e C u r r e n t (A )

Time (ns)

Switching vs Temperature

P e r c e n t C h a n g e T i m e (%)

Temperature (°C)

Application information

The purpose of the ZXGD3103 is to drive a MOSFET as a low-V F Schottky diode replacement in offline power converters. When combined with a low R DS(ON) MOSFET, it can yield significant power efficiency improvement, whilst maintaining design simplicity and incurring minimal component count. Figure 1 and 2 show typical configuration of ZXGD3103 for synchronous rectification in a Flyback and a multiple output resonant converter.

Figure 1. Example connections in Flyback supply

Figure 2. Example connections in LLC supply

Descriptions of the normal operation

The operation of the device is described step-by-step with reference to the timing diagram in Figure 3.

1. The detector monitors the MOSFET Drain-Source voltage.

2. When, due to transformer action, the MOSFET body diode is forced to conduct there is approximately -0.8V on the Drain pin.

3. The detector outputs a positive voltage with respect to ground, this voltage is then fed to the MOSFET driver stage and current is sourced out of the GATE pin.

4. The controller goes into proportional gate drive control — the GATE output voltage is proportional to the on-resistance-induced Drain-Source voltage drop across the MOSFET. Proportional gate drive ensures that MOSFET conducts for majority of the conduction cycle and minimizes body diode conduction time.

5. As the Drain current decays linearly toward zero, proportional gate drive control reduces the Gate voltage so the MOSFET can be turned off rapidly at zero current crossing. The GATE voltage is removed when the Drain-Source voltage crosses the detection threshold voltage to minimize reverse current flow.

6. At zero Drain current, the controller GATE output voltage is pulled low to V G(off) to ensure that the MOSFET is off.

Figure 4 shows typical operating waveforms for ZXGD3103 driving a MOSFET with Q g(TOT) = 82nC in a Flyback converter operating in critical conduction mode.

Figure 3. Timing diagram for a critical conduction mode Flyback converter

Typical waveforms

Fig 4a: Critical conduction mode

Fig 4b: Typical switch ON speed when driving a Q g(TOT)

= 82nC MOSFET

Design considerations

It is advisable to decouple the ZXGD3103 closely to V CC and ground due to the possibility of high peak gate currents with a 1μF X7R type ceramic capacitor as shown in Figure 2. The Gate pins should be as close to the MOSFET’s gate as possible. Also the ground return loop should be as short as possible.

To minimize parasitic inductance-induced premature turn-off issue of the synchronous controller always keep the PCB track length between ZXGD3101’s Drain input and MOSFET’s Drain to less than 10mm. Low internal inductance MOSFET packages such as SO-8 and PolarPak are also recommended for high switching frequency power conversion to minimize body diode conduction.

R1, Q1 D1 and C1 in Figure 1 are only required as a series drop-down regulator to maintain a stable Vcc around 10V from a power supply output voltage greater than 15V.

External gate resistors are optional. They can be inserted to control the rise and fall time which may help with EMI issues.

The proper selection of external resistors R REF and R BIAS is important to the optimum device operation. Select a value for resistor R REF and R BIAS from Table 1 based on the desired Vcc value. This provides the typical ZXGD3103’s detection threshold voltage of 10mV.

Table 1. Recommended resistor values for various supply voltages

V CC R BIAS R REF

5V 1K6 2K0

10V 3K3 4K3

12V 3K9 5K1

15V 5K1 6K8

ZXGD3103N8

Package Outline and Dimensions

ZXGD3103N8

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