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参数资料
| 型号： | LTC1909-8EG |
| 厂商： | Linear Technology |
| 文件页数： | 16/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 47 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 200kHz |
| 占空比： | 90% |
| 电源电压： | 4 V ~ 36 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 其它名称： | LTC19098EG |
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LTC1909-8
OPERATIO
(Refer to Functional Diagram)
on or off accidentally. In both On and Off protocols, the
Table 2. DC/DC Converter Output Voltage
LTC1909-8 does not latch in the Data Low and Data High
bytes. This protects the settings that have already been
loaded into the registers and verified by read-back. Once
the converter is turned on (both SMBON and VRON are
high) the contents of Registers 0 and 1 are protected and
can only be altered with Setup protocols if VRON is pulled
low or two Off protocols are sent to the LTC1909-8 (to
force SMBON low). During Read-Back, the microproces-
sor can check the On or Off state of the controller by testing
the DCON status bit that follows each 5-bit code. This bit
is low only when both SMBON and VRON are high.
Resistor Divider
The resistor divider settings comply with the Intel Desktop
VRM8.4 VID Specifications. The divider consists of a fixed
20k (typical) resistor, R FB1 , connected between the V OSENSE
and FB pins and a variable resistor, R FB2 , from FB to GND.
The FB pin is connected to the V FB pin of the step-down
controller to set the output voltage of the converter. Each
resistor has a tolerance of ± 30% but the divider ratio is
accurate to ± 0.35%. The error budget for the DC/DC con-
verter output voltage must include the ± 0.35% ratio toler-
ance and the ± 1% tolerance in the 0.8V reference. The
output of the DC/DC converter is given by:
V OUT = V REF ? (R FB2 + R FB1 )/R FB2
where V REF = 0.8V is the internal reference voltage of the
converter. Table 2 shows the 32 possible converter output
voltages. The microprocessor controls the SEL pin to se-
lect the contents of one of the registers as the active divider
setting. The SEL pin has a trip point of 1.3V with ± 50mV
of hysteresis and is TTL compatible. It controls an internal
10:5 digital multiplexer and selects the contents of register
0 when pulled low and register 1 when pulled high. When
SEL is toggled, and the new converter output is lower or
VID4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
VID3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
VID2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
VID1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
VID0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
OUTPUT VOLTAGE
2.05V
2.00V
1.95V
1.90V
1.85V
1.80V
1.75V
1.70V
1.65V
1.60V
1.55V
1.50V
1.45V
1.40V
1.35V
1.30V
3.50V
3.40V
3.30V
3.20V
3.10V
3.00V
2.90V
2.80V
2.70V
2.60V
2.50V
2.40V
2.30V
2.20V
2.10V
2.00V
greater by 7.5%, the overvoltage and undervoltage com-
parators of the controller may trip causing the PGOOD pin
of the controller to go low. This condition will recover
automatically as the converter charges up the output or
allows the output to drop to the new voltage setting.
Power Good Timer
The PGTMR or “Power Good Timer” pin is also an open-
drain, N-channel output. It pulls low if the DC/DC converter
is in shutdown or on power-up. When the converter is
turned on, an internal timer keeps PGTMR low for 50 μ s
(typical) which allows time for the converters to enter regu-
lation. Toggling the SEL pin while the converter is turned
on also causes the PGTMR pin to pull low for 50 μ s.
The PGTMR pin may be used to force continuous opera-
tion in the DC/DC converter. If the SEL pin is toggled to
select a lower output voltage, if may take an unacceptably
19098f
16
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| LTC1909-8EG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1909-8EG#TR | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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| LTC1911EMS8-1.5#PBF | 功能描述:IC REG BUCK 1.5V 0.25A 8MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
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