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参数资料
| 型号： | L6918DTR |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, 1200 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封装： | SO-28 |
| 文件页数： | 4/35页 |
| 文件大小： | 431K |
| 代理商： | L6918DTR |
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L6918 L6918A
12/35
Figure 2. ROSC vs. Switching Frequency
DIGITAL TO ANALOG CONVERTER (ONLY FOR MASTER DEVICE L6918A)
The built-in digital to analog converter allows the adjustment of the output voltage from 1.100V to 1.850V with
25mV as shown in the previous table 1. The internal reference is trimmed to ensure the precision of
±0.6% and
a zero temperature coefficient around the 70
° C. The internal reference voltage for the regulation is programmed
by the voltage identification (VID) pins. These are TTL compatible inputs of an internal DAC that is realized by
means of a series of resistors providing a partition of the internal voltage reference. The VID code drives a mul-
tiplexer that selects a voltage on a precise point of the divider. The DAC output is delivered to an amplifier ob-
taining the VPROG voltage reference (i.e. the set-point of the error amplifier). Internal pull-ups are provided for
the VID pins (realized with a 5
A current generator); in this way, to program a logic ”1” it is enough to leave the
pin floating, while to program a logic ”0” it is enough to short the pin to GND.
The voltage identification (VID) pin configuration also sets the power-good thresholds (PGOOD) and the Over/
Under voltage protection (OVP/UVP) thresholds.
The reference for the regulation is generated into the master device and delivered to the slave device through
the VPROG_OUT / VPROG_IN pins.
Programming the ”11111” VID code, the device enters the NOCPU state: both devices keeps all mosfets OFF
and the condition is latched. Cycle the power supply to restart operation. Moreover, in this condition, the OVP
protection is still active into the slave device with a 0.8V threshold.
SOFT START AND INHIBIT
At start-up a ramp is generated from the master device increasing its loop reference from 0V to the final value
programmed by VID in 2048 clock periods. The same reference is present on the VPROG_OUT pin, producing
an increasing loop reference also into the slave device. In this way all the devices involved in the multi-phase
conversion start together with the same increasing reference (See Figure 3).
Before soft start, the lower power MOS are turned ON after that VCCDR reaches 2V (independently by Vcc val-
ue) to discharge the output capacitor and to protect the load from high side mosfet failures. Once soft start be-
gins, the reference is increased and also the upper MOS begins to switch: the output voltage starts to increase
with closed loop regulation. At the end of the digital soft start, the Power Good comparator is enabled and the
PGOOD signal is then driven high (See fig. 3). The Under Voltage comparator is enabled when the reference
voltage reaches 0.8V.
The Soft-Start will not take place, if both VCC and VCCDR pins are not above their own turn-on thresholds. The
soft-start takes place, and the Master device starts to increase the reference, only if the SLAVE_OK bus is at
high level. The Slave device keeps this line shorted to GND until it is ready for the start-up while the master
keeps this line free before soft-start; anyway, this line is shorted to GND if VCC and VCCDR are not above the
turn-ON threshold. During normal operation, if any under-voltage is detected on one of the two supplies, the
devices are shutdown.
0
1000
2000
3000
4000
5000
6000
7000
0
100
200
300
Frequency (KHz)
Rosc(K
)
vs.
12V
0
100
200
300
400
500
600
700
800
900
1000
300
400
500
600
Frequency (KHz)
Rosc(K
)
vs.
GND
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相关代理商/技术参数 |
参数描述 |
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| L6919 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:5 BIT PROGRAMMABLE DUAL-PHASE CONTROLLER WITH DYNAMIC VID MANAGEMENT |
| L6919C | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5 BIT PROGRAMMABLE DUAL-PHASE CONTROLLER WITH DYNAMIC VID MANAGEMENT |
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| L6919CDTR | 功能描述:DC/DC 开关控制器 Prog Dual-Phase Cont RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| L6919E | 功能描述:DC/DC 开关控制器 5-Bit Dual Ph Contlr RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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