Measurement Methode on Circuit

Measurement Methode on Circuit

Voltage Measuring will apply adapter current in while doing measurement ,VALW or voltage always can measure ones adapter plug in with out switching power on but to measuring VS (Voltage on switch) Voltage we need to plug in the adaptor and press power button before doing any measurements.

Testing Resistance and continuity or buzzer test we should removed the adaptor supply. This Measuring Method will need a schematic to see the component application on circuit and also need a component data sheet to see pin description ,input_ output and enable pin to get measuring pin to check voltage rail needs. To get an output we should sure there is an input and triger(enable signal) .If input and triger present but output not present there only 2 possibility happen . 1.Output pin having ground feedback (short circuit) 2.Component is damage . After doing this measurement we will know the missing Voltage problem cause no input ,no triger ,having short or component damage.

Measuring Voltage on circiit we have to know the Voltage rail needs ,thats why we need the schematic to find out measuring point on circuit .For example ,Voltage rail for Main power Laptop motherboard are ADP+ ,this adp+Vallue is depend on adaptor Volatge vallue ,some manafactur for Laptop adaptor are 12V,15V,16.5V,18.5V,19V,20V .make sure you check adaptor Vallue to know how many Volt for ADP+ vallue .Cheking this ADP+ voltage can start on DC jack on circuit .this voltage coming on the first time inserting the circuit than follow the flow according schematic . Every Circuit usualy have part location code to identified connection and interface beetwen one component to others .There are some variation code name on DC jack connector ,they may use code as Jack1,DC_Jack1,PJ1,PCON1 or you can identified DC jack adaptor and look the location code on the circuit nearly dc jack connector .

 After inserting circuit voltage will goes to next component folowing Power sequences

This is a General diagram for Laptop main Power suplly ,Open  the schematic for the circuit you were checking .Adp+ main line will appear on Battery charger page on schematic and 5V ,3V  will appear on 3_5V system on SMPS page .Next checking are  adp+ or Vin sources for SMPS input sources power supply for PU2 .The other requirement ADP+ sources are for both Upper side N channel .

After having 19V adp+ for input Vin SMPS power supply this LDO output voltage will be presented ,some others LDO become embedded power supply and giving triggers to activated SMPS to produce 3V and 5V .and other circuit board LDO become sources for dual comparator to activated SMPS enable signal.

                                                                                                                                                   

HOW TO CHECK 3V_5V(RT8206b) SMPS SYSTEM ON LAPTOP MOTHERBOARD to Produced 3V and 5VALW.

Laptop Motherboard need 3V and 5V power system. This 3V_ALW supply VSB (voltage switch button)-EC Bios IC-EC (embedded controller)-SB(South bridge) and more other important component .5V suplay power Source for any switching transistor and device .(USB-HDD-Optical etc).
Without this 3V and 5V Power circuit board will totally death.

RT8206A/B dual step-down, switch-mode powersupply
(SMPS) controller generates logic-supply voltages
in battery-powered systems. The RT8206A/B includes two
pulse-width modulation (PWM) controllers fixed at 5V/
3.3V or adjustable from 2V to 5.5V. An optional external
charge pump can be monitored through SECFB(RT8206A). 
This device also features a linear regulator
providing a fixed 5V output. The linear regulator provides
up to 70mA output current with automatic linear-regulator
bootstrapping to the BYP(pin 9)switchover source voltage input for the LDO. . 

The RT8206A/B includes
on-board power-up sequencing, the power-good outputs,
internal soft-start, and internal soft-discharge output that
prevents negative voltages on shutdown.

Checking this IC need to know how they work and knowing important input and output Voltage .

INPUT POWER
1.VIN (Pin 6) 6v-25V
Power-supply Input.This input value between 6V to 25V according adapter or battery usage and ADP+power source. VIN is used for the constant on-time
PWM one shot circuits. VIN is also used to power the
linear regulators. The linear regulators are powered by
SMPS1 if VOUT1 is set greater than 4.66V and BYP is
tied to VOUT1.

2.ENLDO (Pin 4) 6V-15V
LDO Enable Input. The REF/LDO is enabled if ENLDO is
within logic high level and disable if ENLDO is less than
the logic low level.This power input between 6V to 15V ,some of other circuit manufacture powered VIN or B+ and the other using diode .
After VIN and ONLDO power present LDO(pin 7) will having output for 5V than supply VL(Voltage Linear) to activate EN1(pin 14) and En2(pin 27).
EN1 is SMPS1 input enable than SMPS output will trigger Upper n channel gate trough UGATE1(pin 15) for 5V .
EN2 is SMPS2 input enable for UGATE2 than SMPS output will trigger Upper n channel gate trough UGATE1(pin 15) for 5V .High-Side MOSFET Floating Gate-Driver Output for SMPS1. and swings between PHASE1/2 and BOOT1/2.
PVCC (pin 19) PVCC is the supply voltage for the low-side MOSFET
driver LGATEx. Connect a 5V power source to the PVCC
pin (bypass with 1uF MLCC capacitor to PGND if
necessary). There is an internal 10Ω connecting from
PVCC to VCC. Make sure that both VCC and PVCC are
bypassed with 1uF MLCC capacitors.PVCC input coming from VL .if LDO no voltage present than PVCC will not triger Lower n channel mosfet.VCC (pin3) is analog suplay input voltage for PWM core.with out this power SMPS will not activated .Be ware also PGND need for SMPS power ground..
If VIN present 6-25V and ONLDO present 6 to 15V but LDO not present .check feedback on pin 7 LDO.if there is no feedback positively RT8206B damage.
If VIN present 6-25V and ONLDO present 6 to 15V and LDO present for 5V positively RT 8206B on good condition .Make sure LDO continuity to VL and triger EN1 and activated SMPS1.SMPS2 will activated after SMPS1 activated and become gate driver for both upper n channel 3V and 5V.
If all power above available but Ugate1 and 2 doesn't comes out check FB1 SMPS1 Feedback Input. Connect FB1 to VCC or GND for
fixed 5V operation. Connect FB1 to a resistive voltagedivider
from VOUT1 to GND to adjust output from 2V to
5.5V.and do same way for FB 2 to adjust output from 2V to 3.3V.

First think to check this SMPS power supply is a main source for VIN supply to power the IC (pin 16) this is an input sources and than automaticaly VREG3 and VREG 5 output LDO present .if this LDO not present even VIN source already present and no shorted feedback on both LDO .we can claim TPS 51125 damage .if this output both output LDO come outs but 3V and 5V inductors not coming check ENTRIP1 and entrip2 input ,this enable signal coming from +V5AUXON from dual comparator gate with sources from VREG5 LDO output.

ISL6237
The main source input goes to VIN and EN_LDO pin than after both sources present ISL 6237 will produce LDO voltage for 5V ,this LDO usualy change the signal name to VL (Voltage linear) as an auxilary power to logic gate enable to enable EN1 and EN2 to activated ISL 6237.

RT8223M

EQ=ED is a marking code for RT 8223 smps power suplay .The main source supply same vallue with adapter main voltage to powered the IC trough VIN (pin 16) and than RT 8223 will generate VREG3 and VREG5 LDO output as auxilary power to enable 3V and 5V system and supply power sources 3V for Embedded controler and Bios IC.

RT 8205 input -output and enable signal
First thing to check this SMPS power suplay is a main source for VIN supply to power the IC (pin 16) this is an input sources present and than automatically VREG3 and VREG 5 output LDO present .if this LDO not present even VIN source already present and no shorted feedback on both LDO .we can claim RT 8205 damage .if this output both ouput LDO come outs but 3V and 5V inductors not coming check ENTRIP1 and entrip2 input ,this enable signal coming from +V5AUXILARY power from dual comparator gate with sources from VREG5 LDO output. but their application will be have 2 variation. check the entrip 1 resistor if they ended to a ground it mean there is no auxilary power needs on circuits.RT 8205 will issued entrip1 after get 3V from master enable triger for 3.3V.