参数资料
| 型号： | ISL62875HRUZ-T |
| 厂商： | Intersil |
| 文件页数： | 14/22页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 20UTQFN |
| 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： | 550kHz |
| 电源电压： | 4.75 V ~ 5.25 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： | 20-UFQFN |
| 包装： | 带卷 (TR) |
ISL62875
The equation for the value of R SET3 is written as
Equation 9:
voltage to the VID0 pin. When SET0 and VCC are tied
together, the following internal reconfigurations take
R SET3 = --------------------------------------------------------------------------------
R SET4 ? ( K V SET4 – K V SET3 )
K V SET3
(EQ. 9)
place:
- VID0 pin opens its 500nA pull-down current sink
R SET1 + R SET2 + R SET3 + R SET4 ? 300k Ω
V SET1 = V REF
V SET2 = V REF ? ? 1 + --------------------------------------------------------------------- ?
The sum of all the programming resistors should be
approximately 300k Ω as shown in Equation 10 otherwise
adjust the value of R SET4 and repeat the calculations.
(EQ. 10)
Equations 11, 12, 13 and 14 give the specific V SET gain
equations for the ISL62875 setpoint reference voltages.
The ISL62875 V SET1 setpoint is written as Equation 11:
(EQ. 11)
The ISL62875 V SET2 setpoint is written as Equation 12:
? R SET1 ?
(EQ. 12)
? R SET2 + R SET3 + R SET4 ?
The ISL62875 V SET3 setpoint is written as Equation 13:
- Reference source selector switch SW4 moves from
INT position (internal 500mV) to EXT position
(VID0 pin)
- VID1 pin is disabled
The converter will now be in regulation when the voltage
on the FB pin equals the voltage on the VID0 pin. As with
resistor-programmed setpoints, the reference voltage
range on the VID0 pin is 500mV to 1.5V. Use Equations
3, 4, and 5 beginning on page 13 should it become
necessary to implement an output voltage-divider
network to make the external setpoint reference voltage
compatible with the 500mV to 1.5V constraint.
Soft-Start and Voltage-Step
Delay
V SET3 = V REF ? ? 1 + -------------------------------------------- ?
? R SET1 + R SET2 ?
? R SET3 + R SET4 ?
(EQ. 13)
Circuit Description
When the voltage on the VCC pin has ramped above the
? R SET1 + R SET2 + R SET3 ?
V SET4 = V REF ? ? 1 + --------------------------------------------------------------------- ?
The ISL62875 V SET4 setpoint is written as Equation 14:
(EQ. 14)
? R SET4 ?
External Setpoint Reference
rising power-on reset voltage V VCC_THR , and the voltage
on the EN pin has increased above the rising enable
threshold voltage V ENTHR , the SREF pin releases its
discharge clamp and enables the reference amplifier
V SET . The soft-start current I SS is limited to 20μA and is
sourced out of the SREF pin into the parallel RC network
V OUT
R FB
FB
-
+
EA
+
V SET
-
V COMP
V REF
500mV
of capacitor C SOFT and resistance R T . The resistance R T
is the sum of all the series connected R SET programming
resistors and is written as Equation 15:
R T = R SET1 + R SET2 + … R SET ( n ) (EQ. 15)
The voltage on the SREF pin rises as I SS charges C SOFT
to the voltage reference setpoint selected by the state of
the VID inputs at the time the EN pin is asserted. The
SREF
SET0
SET1
SW0
SW1
SW2
regulator controls the PWM such that the voltage on the
FB pin tracks the rising voltage on the SREF pin. Once
C SOFT charges to the selected setpoint voltage, the I SS
current source comes out of the 20μA current limit and
decays to the static value set by V SREF ÷ R T . The elapsed
time from when the EN pin is asserted to when V SREF
has reached the voltage reference setpoint is the soft-
start delay t SS which is given by Equation 16:
t SS = – ( R T ? C SOFT ) ? LN ( 1 – ------------------------------ )
SET2
SW3
V START-UP
I SS ? R T
(EQ. 16)
Where:
- I SS is the soft-start current source at the 20μA
limit
FIGURE 7. VOLTAGE PROGRAMMING CIRCUIT
The IC can use an external setpoint reference voltage as
an alternative to VID-selected, resistor-programmed
setpoints. This is accomplished by removing all setpoint
programming resistors, connecting the SET0 pin to the
VCC pin, and feeding the external setpoint reference
14
- V START-UP is the setpoint reference voltage
selected by the state of the VID inputs at the time
EN is asserted
- R T is the sum of the R SET programming resistors
The end of soft-start is detected by I SS tapering off when
capacitor C SOFT charges to the designated V SET voltage
September 18, 2009
FN6905.1
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| ISL62881BHRTZ | 功能描述:直流/直流开关调节器 1 PHS CNTRLR W/INTEG DRVR 32LD 5X5 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| ISL62881BHRTZ-T | 功能描述:直流/直流开关调节器 1 PHS CNTRLR W/INTEG DRVR 32LD 5X5 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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