一,产品概述(General Description)         
VCC and VIN Power-On-Reset (POR)
     The JTMA7324 keeps monitoring the voltage on VIN and VCC pins to prevent
wrong logic operations which may occur when VIN or VCC voltage is not high enough
for internal control circuitry to operate. The VCC POR rising threshold is 2.7V (typical)
with 0.2V hysteresis and VIN POR rising threshold is 2.3V with 0.05V hysteresis.
During startup, the VCC and VIN voltage must exceed the POR threshold. Then the IC starts a starts-up process and ramps up the output voltage to the voltage target. 
Output Under-Voltage Protection (UVP)
In the operational process, if a short-circuit occurs, the output voltage will drop quickly. Before the current-limit circuit responds, the output voltage will fall out of the re-
quired regulation range. The under-voltage continually monitors the FB voltage after
soft-start is completed. If a load step is strong enough to pull the output voltage lower
than the under-voltage threshold, the IC shuts down converter’s output.The under-voltage threshold is 50% of the nominal output voltage. The under-voltage comparator has a
built-in 3µs noise filter to prevent the chips from wrong UVP shutdown being caused by noise. The JTMA7324 will be latched after under-voltage protection.
Over-Voltage Protection (OVP)
The over-voltage function monitors the output voltage by FB pin. When the FB voltage increases over 125% of the reference voltage due to the high-side MOSFET failure or
for other reasons, the over-voltage protection comparator will force the low-side MOSFET gate driver high. This action actively pulls down the output voltage and eventually
attempts to blow the internal bonding wires. As soon as the output voltage is within regulation, the OVP comparator is disengaged. The chip will restore its normal operation 
Over-Temperature Protection (OTP)
The over-temperature circuit limits the junction temperature of the JTMA7324. When the junction temperature exceeds TJ = 160 oC, a thermal sensor turns off the both power MOSFETs, allowing the devices to cool.The thermal sensor allows the converters to
start a startup process and to regulate the output voltage again after the junction temperature cools by 50oC. The OTP is designed with a 50 oC hysteresis to lower the average TJduring continuous thermal overload conditions, increasing lifetime of the JTMA7324. 
Current-Limit Protection 
The JTMA7324 monitors the output current, flows through the high-side and low-side
power MOSFETs, and limits the current peak at current-limit level to prevent the IC
from damaging during overload, short-circuit and overvoltage conditions. Typical high
side power MOSFET current limit is 6A, and low side MOSFET current limit is 1.9A.
Soft-Start
The JTMA7324 has a built-in soft-start to control the rise rate of the output voltage and
limit the input current surge during start-up. During soft-start, an internal voltage ramp
connected to one of the positive inputs of the error amplifier, rises up from 0V to 0.95V to replace the reference voltage (0.8V) until the voltage ramp reaches the reference voltage. During soft-start without output overvoltage, the JTMA7324 converter’s sinking capability is disabled until the output voltage reaches the voltage target.
Soft-Stop
At the moment of shutdown controlled by EN signal, under-voltage event or overtemperature protection, the JTMA7324 initiates a soft-stop process to discharge the output voltage in the output capacitors. Certainly, the load current also discharges the output voltage. During soft-
stop, the internal voltage ramp (VRAMP) falls down from 0.95V to 0V to replace the eference voltage. Therefore, the output voltage falls down slowly at the light load. After the
soft-stop interval elapses, the soft-stop process ends and the IC turns on the low-side power MOSFET.
Enable and Shutdown
Driving EN to ground places the JTMA7324 in shutdown.In shutdown mode, the internal power MOSFETs turns off, all internal circuitry shuts down and the quiescent supply current reduces to less than 20µA.
Power Good Indicator
POK is actively held low in shutdown and soft-start status.In the soft-start process, the POK is an open-drain. Whenthe soft-start is finished, the POK is released. In normaloperation, the POK window is from 87.5% to 112.5% of the converter reference voltage. When the output voltage has to stay within this window, POK signal will become high after 0.5ms internal delay. When the output voltage outruns 82.55% or 117.5% of the target voltage, POK sig-
nal will be pulled low immediately. In order to prevent false POK drop, capacitors need to parallel at the output to confine the voltage deviation with severe load step transient.
二.产品特点(Features)
High Efficiency up to 94%
- Automatic Skip/PWM Mode Operation
Adjustable Output Voltage from 0.8V to V IN
Operating from 2.9 to 6V Supply
Integrated 85mΩ High Side / 75mΩ Low Side
MOSFETs
Low Dropout Operation: 100% Duty Cycle
Stable with Low ESR Ceramic Capacitors
Current up to 4A
Power-On-Reset Detection on VCC and VIN
Integrate Soft-Start and Soft-Stop
Over-Temperature Protection
Over-Voltage Protection
Under-Voltage Protection
High/ Low Side Current Limit
Power Good Indication
Enable/Shutdown Function
Available in SOP-8P and TDFN3x3-10 Packages
Lead Free and Green Devices Available
(RoHS Compliant)
三,应用范围 (Applications)
 Notebook Computer & UMPC
·  LCD Monitor/TV
·  Set-Top Box
DSL, Switch HUBr
Portable Instrument
四.下载产品资料PDF文档 

jtma7324

jtma7325

五,产品封装图 (Package)

六.电路原理图


七,功能概述
JTMA7324 is a synchronous buck converters with integrated 85m Ω high side and 75m Ω low side power
MOSFETs. The JTMA7324 with a current-mode control scheme can convert wide input voltage of 2.9V to 6V to
the output voltage adjustable from 0.8V to 6V to provide excellent output voltage regulation.
The JTMA7324 is equipped with an automatic Skip/PWM mode operation. At light load , the IC operates in the Skip
mode to reduce the switching losses. At heavy load, the IC works in PWM mode. The JTMA7324 is also equipped with Power-on-reset, soft start, soft-stop, and whole protections (under-voltage,over-voltage, over-temperature and current-limit) into a single package.This device, available in SOP-8P and TDFN3x3-10
packages, provides a very compact system solution external components and PCB area.
八,相关产品

Part_No	Package & Pins	Topology	Architecture	No. of PWM Outputs	Drive Lout (A)	Vin (V)		Fmax(Khz)	Vref (V)	R-Top (milohm)	R-Sync (milohm)	Iq (No load) (uA)
						min	max
jtma7083	TQFN5x6-28	Buck	CM	1	5	4.5	26	380	0.8	50	20	1000
jtma7085	SOP-8	Buck	CM	1	2	4.5	26	380	0.8	100		1000
jtma7089	SOP-8P	Buck	CM	1	4	4.5	26	380	0.8	80		1000
jtma7104	SOT-23-5	Buck	CM	1	1	2.7	6	1500	0.6	280	250	25
	TSOT-23-5
jtma7104A	SOT-23-5	Buck	CM	1	1	2.7	6	1500	0.6	280	250
jtma7142	SOP-8	Buck	CM	1	3	4.3	14	500	0.8	70	70	500
jtma7145	SOP-8P	Buck	CM	1	3	4.3	14	500	0.8	55	45	500
jtma7153B	TDFN3x3-10				3	2.6	5.5	2000	0.8	110	110	460
jtma7176	TDFN3x3-10	Buck	CM	2	1	2.7	6	1500	0.6	280	250	500
jtma7176A	TDFN3x3-10	Buck	CM	2	1	2.7	6	1500	0.6	280	250
jtma7178	TDFN2x2-6	Buck	CM	1	1	2.7	6	1500	0.6	280	250	25
jtma7178A	TDFN2x2-6	Buck	CM	1	1	2.7	6	1500	0.6	280	250
jtma7179	TDFN3x3-12	Buck	CM	2	1	2.7	6	1500	0.6	280	250	25
jtma7179A	TDFN3x3-12	Buck	CM	2	1	2.7	6	1500	0.6	280	250
jtma7290	TDFN2x2-8		CM	1	1	3.3	8	1500	0.6	280	250	25
jtma7300	SOP-8	Buck	CM	1	2	4.5	24	340	0.925	110	110	1900
jtma7301	SOP-8P	Buck	CM	1	3	4.5	24	340	0.925	110	110	1900
jtma7302	SOP-8	Buck	CM	1	2	4.5	24	340	0.92	130	130	1900
jtma7302B	SOP-8P	Buck	CM	1	2	4.5	24	340	0.92	130	130	1900
jtma7303	SOP-8P	Buck	CM	1	3	4.5	24	340	0.92	85	85	1900
jtma7304	SOP-8P	Buck	CM	1	4	4.5	24	340	0.8	85	85	1900
jtma7311	SOP-8P	Buck	CM	1	3	4.5	24	1300	0.925	110	110	1900
jtma7312	SOP-8	Buck	CM	1	2	4.5	24	340	0.925	110	110	1900
jtma7313	SOP-8P	Buck	CM	1	3	4.5	24	340	0.925	110	110	1900
jtma7314	TSOT-23-8	Buck	CM	1	2	4.5	24	500	0.8	150	70	500
jtma7322	SOP-8P	Buck	CM	1	2	2.5	6	1000	0.8	85	75	460
	TDFN3x3-10
jtma7323	SOP-8P	Buck	CM	1	3.2	2.5	6	1000	0.8	85	75	460
	TDFN3x3-10
jtma7324	SOP-8P	Buck	CM	1	4	2.5	6	500	0.8	85	75	460
	TDFN3x3-10
jtma7325	SOP-8P	Buck	CM	1	5	2.5	6	1000	0.6	65	55	460
jtma7334	SOP-8	Buck	CM	1	2	4.5	24	340	0.8	110	110	1900
jtma7335	SOP-8P	Buck	CM	1	3	4.5	24	340	0.8	110	110	1900
jtma7336	TDFN3x3-10	Buck	CM	1	2	4.5	24	340	0.8	110	110	1900
jtma7337	TDFN3x3-10	Buck	CM	1	3	4.5	24	340	0.8	110	110	1900
jtma8713	TQFN4x4-23	Buck	COT	1	6	2.7	28	100~1000	0.8	30	9	750
jtma8802	TQFN5x6-28	Buck	COT	1	8	3	25	500	0.75	12	12	400
jtma8804	TDFN3x3-10	Buck	CM	1	3	2.6	6	1000	0.6	65	55	460
jtma8805	TDFN3x3-10	Buck	CM	1	3	2.6	6	1000	0.6	75	55	460
jtma8807	TQFN3x3-16	Buck	COT	1	8	6	28	500	0.6	24	14	80
jtma8824	TSOT-23-6	Buck	CM	1	1	2.7	5.5	1500	0.6	280	250	25
jtma8835	TDFN3x3-10	Buck	CM	1	3	4.5	24	600	0.8	70	70	400
jtma7414	TSOT-23-8A	Buck	CM	1	2	4.5	24	500	0.788	150	70	1000
jtma7319	TSOT-23-8A	Buck	CM	1	2.5	4.5	24	500	0.807	140	60	1000
jtma8715	TQFN 4x4 23	Buck	COT	1	6	2.7	28	100~1000	0.8	30	12	700
jtma8716A	TQFN 5x5 30	Buck	COT	1	12	2.7	28	300~1000	0.8	14.6	7.8	750
jtma8715	TQFN 4x4 23	Buck	COT	1	6	2.7	28	100~1000	0.8	30	12	700
jtma8805B	TDFN 3x3 10	Buck	CM	1	3	2.6	6	1000	0.8	75	55	460
jtma8805A	TDFN 3x3 10	Buck	CM	1	3	2.6	6	1000	0.8	75	55	460