The JTMA7108 is a dual-channel, constant on-time, and synch

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 JTMA7108 is a dual-channel, constant on-time, and
synchronous PWM controller which drives dual N-channel MOSFETs
for each channel. The JTMA7108 steps down high voltage of a battery
to generate low-voltage chipset or RAM supplies in notebook computers.
The JTMA7108 provides excellent transient response and accurate DC voltage output in either PFM or PWM mode. In PFM mode, the TMA7108 provides very high efficiency over light to heavy loads with loading-modu-
lated switching frequencies. The Forced-PWM mode works nearly at constant frequency for low-noise requirements.
The JTMA7108 is equipped with accurate current-limit,output under-voltag, and output over-voltage protections,perfect for NB applications. A Power-On-Reset function monitors the voltage on V CC to prevent wrong opera-tion during power on. A soft-start ramps up the output voltage with programmable slew rate to reduce the start-up current. A soft-stop function actively discharges the output capacitors with controlled reverse inductor current. At the end of the soft-stop, the JTMA7108 forces
LGATE high to prevent over-voltage in shutdown. The JTMA7108 has individual enable controls for each channel. Pulling both EN pin low shuts down the whole chip with low quiescent current close to zero.
The JTMA7108 is available in SSOP-28 and QFN4x4-24 packages.

二.产品特点(Features)
1.）Adjustable Output Voltage up to 5.5V
- 0.9V Reference Voltage
- ±1% Accuracy Over Temperature
2.）Operates from an Input Battery Voltage Range of
3.）5V to 24V or from 3.3V/5V System Rail
4.）Power-On-Reset Monitoring on VCC Pin
Selectable Forced PWM or Automatic PFM/PWM Mode
5.）Constant-On-Time Control Scheme
- Switching Frequency Compensation for PWM Mode
- Constant Switching Frequency (CH1: 345kHz,
CH2: 255KHz) in PWM Mode with DC Output Current
6.）Excellent Line and Load Transient Responses
7.）Adjustable Soft-Start and Soft-Stop
8.）Power-Good Outputs for both Channels
9.）Adjustable Current-Limit Protection
- Using Sense Resistor or MOSFET’s RDS(ON)
10.）115% Over-Voltage Protection
- No Negative Output Voltage Occurred
11.）70% Under-Voltage Protection
12.）Adaptive Dead-Time Control
- Sensing G-to-S Voltage of Power MOSFETs
13.）Shutdown Control for both Channels
14.）28-pin SSOP (SSOP-28) and 4mmx4mm 24-lead
QFN (QFN4x4-24) Packages
15.）Lead Free and Green Devices Available
三,应用范围 (Applications)
Note Book Computers
- Chipset/RAM Supplies as low as 0.9V
- 1.8V and 2.5V Supplies
Step-Down Converters Requiring High Efficiency

四.下载产品资料PDF文档

JTMA71408