The JTMA7199 is a single-phase, constant-on-time, and sync

1.产品概述 2.产品特点 3.应用范围 4.下载产品资料PDF文档
5.产品封装图 6.电路原理图 7.功能概述 8.相关产品

一,产品概述(General Description)
The JTMA7199 is a single-phase, constant-on-time, and synchronous
PWM controller, which drives N-channel MOSFETs. An internal 0.5V temperature-compensated reference voltage with high accuracy is designed to meet the
requirement of low output voltage applications. The JTMA7199 steps down
high voltage to generate low-volt-age chipset or RAM supplies in notebook
computers.The PWM controller operates fixed 300kHz pseudo-con-
stant frequency PWM with an adaptive constant-on-time control. The device
provides excellent transient response and accurate DC voltage output in either
PFM or PWM Mode. In Pulse Frequency Mode (PFM), the JTMA7199 pro-
vides very high efficiency over light to heavy loads with loading-modulated
switching frequencies. The device works in ultrasonic mode with PFM at no
load. The unique ultrasonic mode maintains the switching frequency above
20kHz, which eliminates noise in audio applications.
The JTMA7199 is equipped with accurate over-current,output
under-voltage, and output over-voltage protections.A Power-On-Reset
function monitors the voltage on VCC to prevent wrong operation during
power-on. The JTMA7199 has a 1.5ms digital soft-start to ramp up the
output voltage to reduce the start-up current. A soft-stop function actively
discharges the output capacitors with controlled reverse inductor current.
The JTMA7199 is available in TDFN3x3-10 package

二.产品特点(Features)
1.)Operates from An Input Battery Voltage Range of +3V to +25V
±0.6% 0.5V Reference Over Line, Load Regulation, and
Operating Temp.
2.)Drive Dual Low Cost N-Channel MOSFETs
Adaptive Shoot-Through Protection
3.)Power-On-Reset Monitoring on VCC Pin
4.)PFM Mode for Increasing Light Load Efficiency
5.)Constant-On-Time Control Scheme
Switching Frequency Compensation for PWM Operation
6.)300kHz Constant Switching Frequency
7.)Integrated MOSFET Drivers and Bootstrap Diode
8.)Internal Soft-Start and Soft-Stop
9.)Power Good Monitoring
10.)70% Under-Voltage Protection
11.)125% Over-Voltage Protection
Using Low-Side MOSFET’s RDS(ON)
12.)Over-Temperature Protection
13.)TDFN-10 3mmx3mm Package
14.)Lead Free and Green Devices Available (RoHS Compliant)
三,应用范围 (Applications)
Notebook
Low Cost PC
Wide Input DC/DC Regulators

四.下载产品资料PDF文档

JTMA7199

五,产品封装图 (Package)

FUNCTION

PIN		FUNCTION
NO.	NAME	FUNCTION
1
BOOT	This pin provides ground referenced bias voltage to the high-side MOSFET driver. A bootstrap circuit with a diode connected to 5V is used to create a voltage suitable to drive a logic-level N-channel MOSFET.
2	UGATE	Connect this pin to the high-side N-channel MOSFET’s gate. This pin provides gate drive for the high-side MOSFET.
3	PHASE	The pin provides return path for the high-side MOSFET driver’s pull-low current. Connect this pin to the high-side MOSFET’s source.
4	GND	The GND terminal provides return path for the IC’s bias current and the low-side MOSFET driver’s pull-low current. Connect the pin to the system ground via very low impedance layout on PCBs.
5	LGATE/OCSET	Low-side Gate Driver Output and Over-Current Setting Input. This pin is the gate driver for low-side MOSFET.
6	VCC	Connect this pin to a 5V supply voltage. This pin provides bias supply for the control circuitry and the low-side MOSFET driver. The voltage at this pin is monitored for the Power-On-Reset (POR) purpose. Decoupling capacitor (4.7µF) be connected to GND for noise decoupling.
7	FB	Output Voltage Feedback pin. This pin is connected to the resistive divider that set the desired output voltage. The POK, UVP, and OVP circuits detect this signal to report output voltage status.
8	VOUT	The VOUT pin makes a direct measurement of the converter output voltage. The VOUT pin should be connected to the top feedback resistor at the converter output.
9	POK	POK is an open drain output used to indicate the status of the output voltage. Connect the POK pin to +5V through a pull-high resistor.
10	EN/EXTREF	Enable/Shutdown Pin or External Reference Selection of The PWM Controller.

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