The JTMA7066, JTMA7067N has two synchronous buck PWM control(4)

regulator 5.8V was designed for VCC (5V); the range of the shunt regulator was designed over the usual range
4.5V to 5.5V of typical 5V power supplies.
Connect a resistor from VCC12 to VCC for shunt regula-tor and for the supply current. The input supply current of
VCC is 7mA; minimum shunt regulator current is about 7mA, and therefore the 20mA shunt regulator current is
enough; thus, the typical value, 300Ω of the resistor is recommended. The relation among minimun shunt regu-
lator current,
MOSFET Selection
The selection of the N-channel power MOSFETs are de-termined by the RDS(ON), reverse transfer capacitance (CRSS)
and maximum output current requirement. The losses in the MOSFETs have two components: conduction loss and
transition loss. For the upper and lower MOSFET, the losses are approximately given by the following :
PUPPER = Iout 2(1+ TC)(RDS(ON))D + (0.5)(Iout)(VIN)(tsw)FS
PLOWER = Iout 2(1+ TC)(RDS(ON))(1-D)
where IOUT is the load current TC is the temperature dependency of RDS(ON)
FS is the switching frequency tsw is the switching interval D is the duty cycle Note that both MOSFETs have conduction
losses while the upper MOSFET include an additional transition loss.The switching internal, t sw, is a function of the reverse
transfer capacitance CRSS.
The (1+TC) term is to factor in the temperature depen-dency of the RDS(ON) and can be extracted from the “RDS(ON)
vs. Temperature” curve of the power MOSFET.

Connecting One Input from Another Output
It can be connected one of the 3 outputs as the input voltage to the 2nd. In these cases the output current of the
first output includes its own load current and the 2nd output’s load current. Therefore, the components of the
first output must be designed and sized for the both outputs. The soft-start of first output must be faster than
the 2nd output. If the first output is not present when the 2nd output tries to start up, the 2nd output cannot get
smooth and controlled output voltage rise, even cause short-circuit protection.

Short Circuit Protection
The JTMA7066 provides a simple short circuit protection function, and it is not easy to predict its performance, since
many factors can affect how well it works. Therefore, the limitations and suggestions of this method must be pro-
vided for users to understand how to work it well.· The short circuit protection was not designed to work
for the output in initial short condition. In this case, the short circuit protection may not work, and damage the

MOSFETs. If the circuit still works, remove the short can cause an inductive kick on the phase pin, and it may dam-
age the IC and MOSFETs.· If the resistance of the short is not low enough to cause protection, the regulator will work
as the load has increased, and continue to regulate up until the MOSFETs is damaged. The resistance of the short
should include wiring, PCB traces, contact resistances, and all of the re- turn paths.
· The higher duty cycle will give a higher COMP voltage level, and it is easy to touch the trip point.
The compensation components also affect the response of COMP voltage; smaller caps may give a faster response.
· The output current has faster rising time during short; the COMP pin will have a sharp rise. However, if the cur-
rent rises too fast, it may cause a false trip. The output capacitance and its ESR can affect the rising time of the
current during short.

Layout Consideration
In high power switching regulator, a correct layout is im-portant to ensure proper operation of the regulator. In
general, interconnecting impedances should be mini-mized by using short, wide printed circuit traces. Signal
and power grounds are to be kept separate and finally combined using ground plane construction or single point
grounding. Figure 15 illustrates the layout, with bold lines indicating high current paths; these traces must be short
and wide. Components along the bold lines should be placed lose together. Below is a checklist for your layout:
· The metal plate of the bottom of the packages (TSSOP-24 and QFN5x5-32) must be soldered to the PCB and
connected to the GND plane on the backside through several thermal vias.· Keep the switching nodes (UGATE,
LGATE and PHASE)away from sensitive small signal nodes since thesenodes are fast moving signals. Therefore,
keep traces to these nodes as short as possible.· The traces from the gate drivers to the MOSFETs (UG1,
LG1, UG2, LG2, DRIVE3) should be short and wide.· Decoupling capacitor, compensation component, the (责任编辑：oumao18)