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参数资料
| 型号： | ISL62871HRUZ-T |
| 厂商： | Intersil |
| 文件页数： | 15/25页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 16-TQFN |
| 标准包装： | 3,000 |
| 系列： | Robust Ripple Regulator™ (R³) |
| PWM 型： | 控制器 |
| 输出数： | 1 |
| 频率 - 最大： | 330kHz |
| 占空比： | 100% |
| 电源电压： | 3.3 V ~ 25 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： | -10°C ~ 100°C |
| 封装/外壳： | 16-UFQFN |
| 包装： | 带卷 (TR) |
ISL62871, ISL62872
means if the FB pin voltage falls below 102% x 1.0V = 1.02V
for more than 2μs, the LGATE gate-driver will turn off the
low-side MOSFET. If the output voltage rises again, the
LGATE driver will again turn on the low-side MOSFET when
the FB pin voltage is above the rising overvoltage threshold
V OVRTH for more than 2μs. By doing so, the IC protects the
load when there is a consistent overvoltage condition.
Undervoltage
The UVP fault detection circuit triggers after the FB pin
voltage is below the undervoltage threshold V UVTH for more
than 2μs. For example if the converter is programmed to
regulate 1.0V at the FB pin, that voltage would have to fall
below the typical V UVTH threshold of 84% for more than 2μs
of the transient and work in concert with the error amplifier
V ERR to maintain output voltage regulation. Once the
transient has dissipated and the control loop has recovered,
the PWM frequency returns to the nominal static 300KHz.
Modulator
The R 3 modulator synthesizes an AC signal V R , which is an
analog representation of the output inductor ripple current.
The duty-cycle of V R is the result of charge and discharge
current through a ripple capacitor C R . The current through
C R is provided by a transconductance amplifier g m that
measures the input voltage (V IN ) at the PHASE pin and
output voltage (V OUT ) at the VO pin. The positive slope of
V R can be written as Equation 27:
in order to trip the UVP fault latch. In numerical terms, that
would be 84% x 1.0V = 0.84V. When a UVP fault is declared,
V RPOS = ( g m ) ? ( V IN – V OUT ) ? C R
(EQ. 27)
V RNEG = g m ? V OUT ? C R
the PGOOD pin will pull-down to 95 Ω and latch-off the
converter. The fault will remain latched until the EN pin has
been pulled below the falling EN threshold voltage V ENTHF
or if VCC has decayed below the falling POR threshold
voltage V VCC_THF .
Over-Temperature
When the temperature of the IC increases above the rising
threshold temperature T OTRTH , it will enter the OTP state
that suspends the PWM, forcing the LGATE and UGATE
gate-driver outputs low. The status of the PGOOD pin does
not change nor does the converter latch-off. The PWM
remains suspended until the IC temperature falls below the
hysteresis temperature T OTHYS at which time normal PWM
operation resumes. The OTP state can be reset if the EN pin
is pulled below the falling EN threshold voltage V ENTHF or if
VCC has decayed below the falling POR threshold voltage
The negative slope of V R can be written as Equation 28 :
(EQ. 28)
Where, g m is the gain of the transconductance amplifier.
A window voltage V W is referenced with respect to the error
amplifier output voltage V COMP , creating an envelope into
which the ripple voltage V R is compared. The amplitude of
V W is controlled internally by the IC. The V R, V COMP, and
V W signals feed into a window comparator in which V COMP
is the lower threshold voltage and V W is the higher threshold
voltage. Figure 11 shows PWM pulses being generated as
V R traverses the V W and V COMP thresholds. The PWM
switching frequency is proportional to the slew rates of the
positive and negative slopes of V R; it is inversely
proportional to the voltage between V W and V COMP.
VCC_THF . All other protection circuits remain functional
V
while the IC is in the OTP state. It is likely that the IC will
detect an UVP fault because in the absence of PWM, the
output voltage decays below the undervoltage threshold
V UVTH .
Theory of Operation
RIPPLE CAPACITOR VOLTAGE C R
WINDOW VOLTAGE V W
The modulator features Intersil’s R 3 Robust-Ripple-
Regulator technology, a hybrid of fixed frequency PWM
control and variable frequency hysteretic control. The PWM
frequency is maintained at 300KHz under static
continuous-conduction-mode operation within the entire
specified envelope of input voltage, output voltage, and
output load. If the application should experience a rising load
transient and/or a falling line transient such that the output
voltage starts to fall, the modulator will extend the on-time
and/or reduce the off-time of the PWM pulse in progress.
Conversely, if the application should experience a falling
load transient and/or a rising line transient such that the
output voltage starts to rise, the modulator will truncate the
on-time and/or extend the off-time of the PWM pulse in
progress. The period and duty cycle of the ensuing PWM
pulses are optimized by the R 3 modulator for the remainder
15
ERROR AMPLIFIER VOLTAGE V COMP
PWM
FIGURE 11. MODULATOR WAVEFORMS DURING LOAD
TRANSIENT
Synchronous Rectification
A standard DC/DC buck regulator uses a free-wheeling
diode to maintain uninterrupted current conduction through
the output inductor when the high-side MOSFET switches off
for the balance of the PWM switching cycle. Low conversion
efficiency as a result of the conduction loss of the diode
FN6707.0
August 14, 2008
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相关代理商/技术参数 |
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| ISL62872HRUZ | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:PWM DC/DC Controller With VID Inputs For Portable GPU Core-Voltage Regulator |
| ISL62872HRUZ-T | 功能描述:IC REG CTRLR BUCK PWM 20-TQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:Robust Ripple Regulator™ (R³) 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL62873 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:PWM DC/DC Controller with VID Inputs for Portable GPU Core-Voltage Regulator |
| ISL62873HRUZ-T | 功能描述:IC REG CTRLR BUCK PWM 16UTQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:Robust Ripple Regulator™ (R³) 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL62875 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:PWM DC/DC Controller with VID Inputs for Portable GPU Core-Voltage Regulator |
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