Application Guide for HB6296 High Voltage and High Current Charging Management Chip for 2-10 Cells Lithium Battery 24V Lead Acid

htdzxiaoyao

Application Guide for HB6296 High Voltage and High Current Charging Management Chip for 2-10 Cells Lithium Battery 24V Lead Acid [Copy link]

HB6296 Application Guide

1. Wiring:

A: The current detection resistor is placed close to the hb6296 . The voltage signal on the detection resistor is very weak. To reduce interference, it must be placed close to the hb6296 . The corresponding R17 in the application diagram is used.

b: The capacitor on Regn ( pin 15 ) must be close to hb6296 , the closer the better, the capacitor and IC should be placed on the same side to avoid drilling holes for routing.

c : The main circuit follows the general DC-DC wiring requirements. From input to output, the ground wire should not be a single piece, but a strip (input + , - should not be shorted with output + , - ). The current must pass through two electrolytic filters.

d: Single point grounding, connect the ground of hb6296 and the ground of surrounding components (excluding mosfet ) as a signal line. Then connect it to the ground of battery capacitor, the line width should be 2mm or more.

2: a : Many customers ( 80% ) like to connect VCC ( pin 3 ) to the right end of the anti-reverse diode, which is wrong. PWM mosfet has a parasitic diode, and the battery voltage will be transmitted to the right end of the anti-reverse diode through the parasitic diode of PWM . If connected in this way, the VCC of HB6290 & 6293 will always have power, consuming battery power ( 0.8ma ), and will also cause logic confusion of HB6290 & HB6293 .

b: The maximum current of ao4480 is only 3A , which is the peak current on the datasheet (under certain test conditions). Otherwise , a small number of mosfets will be damaged. Aod526 can carry 3-5A , and above 5A , the upper tube uses two 252 package mosfets , and the lower tube uses one 252 package .

c: The electrolytic capacitor connected in parallel with the battery must be at least 100uf , otherwise it will spark when plugging and unplugging the battery, and a small part of the IC will be damaged. The more sections there are, the larger the capacitance.

d: For a small number of customers, NTC is needed . The NTC leads are far away. When plugging and unplugging the battery ( NTC is usually in the battery), it is easy to introduce ESD and damage the IC . To protect the IC , a 470-1K resistor is required in series with the lower 6 pins . At the same time, a 62K resistor is connected to the ground.

3: This IC is a classic step-down circuit, and the inductance calculation formula can be used as a reference.

Inductance calculation formula: L= ( Vin-Vbat ) *Ton/(Imax/D) . Where D is the duty cycle, Ton=T*D . L=(Vin-Vbat)*T . T is the switching period, Vbat is 3.7*n . The switching frequency of HB6296 is variable, the voltage is high (above 30V ) is 270K , ( T=3.8us ). The frequency of low voltage (below 30V ) is 360Khz , which is 2.8us . For 4 lithium batteries, the input voltage is 25V and the output current is 5A . Then L= ( 25-14.8 ) *2.8us/5A=5.7uH , take 6.8uh .

Five: Heat dissipation. For low voltage (less than 35V ), my test results show that HB6296 does not need a heat sink, P=(35V-5.4)*12ma=360mw, HB6296 has its own heat sink, so it is not necessary to add an external heat sink. If two upper tube MOSFETs are driven , Icc will rise to 20ma , then P= ( 35-5.4 ) *20ma=600mw , and a heat sink should be considered. The heat dissipation of MOSFETs should also be paid special attention to. The upper tube ( PWM tube) should be considered mainly.

Six: It is best to choose a mosfet with small Ciss , short tr and tf . In this way, the mosfet will generate less heat, and the hb6296 will also generate less heat. But it cannot be too small, otherwise the inductor waveform will be too steep, and emc and emi will not pass, and it will also interfere with hb6296 .

7: For EMC and EMI considerations, the main current loop should be as short as possible, and the AC loop should also be as short as possible, especially on the LX net . The AC path can use 4.7uf ceramic capacitors placed in relevant places to effectively reduce the length of the AC path.

Jacktang

I think the article should have pictures.

ulykiss

Is there any relevant information? I just want to make a 3-cell lithium battery charging management solution recently. Do you have drawings or technical support?