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参数资料
| 型号： | LTC3827IG-1#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 2,000 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 580kHz |
| 占空比： | 99.4% |
| 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： | 带卷 (TR) |
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LTC3827-1
APPLICATIONS INFORMATION
EXTV CC LDO regulates it to 7.5V. Each of these can supply
a peak current of 50mA and must be bypassed to ground
with a minimum of 4.7μF tantalum, 10μF special polymer,
or low ESR electrolytic capacitor. A ceramic capacitor
with a minimum value of 4.7μF can also be used if a 1Ω
resistor is added in series with the capacitor. No matter
what type of bulk capacitor is used, an additional 1μF ce-
ramic capacitor placed directly adjacent to the INTV CC and
PGND IC pins is highly recommended. Good bypassing
is needed to supply the high transient currents required
by the MOSFET gate drivers and to prevent interaction
between the channels.
High input voltage applications in which large MOSFETs
are being driven at high frequencies may cause the maxi-
mum junction temperature rating for the LTC3827-1 to be
exceeded. The INTV CC current, which is dominated by the
gate charge current, may be supplied by either the 5.25V
V IN LDO or the 7.5V EXTV CC LDO. When the voltage on
the EXTV CC pin is less than 4.7V, the V IN LDO is enabled.
Power dissipation for the IC in this case is highest and is
equal to V IN ? I NTVCC . The gate charge current is dependent
on operating frequency as discussed in the Ef?ciency
Considerations section. The junction temperature can be
estimated by using the equation given in Note 2 of the Elec-
trical Characteristics. For example, the LTC3827-1 INTV CC
current is limited to less than 24mA from a 24V supply when
in the G package and not using the EXTV CC supply:
T J = 70°C + (24mA)(24V)(95°C/W) = 125°C
To prevent the maximum junction temperature from being
exceeded, the input supply current must be checked while
operating in continuous conduction mode (PLLIN/MODE
= INTV CC ) at maximum V IN .
When the voltage applied to EXTV CC rises above 4.7V, the
V IN LDO is turned off and the EXTV CC LDO is enabled. The
EXTV CC LDO remains on as long as the voltage applied to
EXTV CC remains above 4.5V. The EXTV CC LDO attempts
to regulate the INTV CC voltage to 7.5V, so while EXTV CC
is less than 7.5V, the LDO is in dropout and the INTV CC
voltage is approximately equal to EXTV CC . When EXTV CC
is greater than 7.5V up to an absolute maximum of 10V,
INTV CC is regulated to 7.5V.
Using the EXTV CC LDO allows the MOSFET driver and
control power to be derived from one of the LTC3827-1’s
switching regulator outputs (4.7V ≤ V OUT ≤ 10V) during
normal operation and from the V IN LDO when the output
is out of regulation (e.g., start-up, short-circuit). If more
current is required through the EXTV CC LDO than is speci-
?ed, an external Schottky diode can be added between the
EXTV CC and INTV CC pins. Do not apply more than 10V to
the EXTV CC pin and make sure than EXTV CC ≤ V IN .
Signi?cant ef?ciency and thermal gains can be realized
by powering INTV CC from the output, since the V IN cur-
rent resulting from the driver and control currents will be
scaled by a factor of (Duty Cycle)/(Switcher Ef?ciency). For
5V to 10V regulator outputs, this means connecting the
EXTV CC pin directly to V OUT . Tying the EXTV CC pin to a 5V
supply reduces the junction temperature in the previous
example from 125°C to:
T J = 70°C + (24mA)(5V)(95°C/W) = 81°C
However, for 3.3V and other low voltage outputs, addi-
tional circuitry is required to derive INTV CC power from
the output.
The following list summarizes the four possible connec-
tions for EXTV CC :
1. EXTV CC Left Open (or Grounded). This will cause
INTV CC to be powered from the internal 5.25V regulator
resulting in an ef?ciency penalty of up to 10% at high
input voltages.
2. EXTV CC Connected directly to V OUT . This is the normal
connection for a 5V to 10V regulator and provides the
highest ef?ciency.
3. EXTV CC Connected to an External supply. If an external
supply is available in the 5V to 10V range, it may be
used to power EXTV CC providing it is compatible with
the MOSFET gate drive requirements.
38271fe
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| LTC3827IUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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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