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参数资料
| 型号： | SP7653ER-L/TR |
| 厂商： | Exar Corporation |
| 文件页数： | 5/15页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 3A 26DFN |
| 标准包装： | 3,000 |
| 系列： | Power Blox™ |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 19 V |
| 输入电压： | 2.5 V ~ 20 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 1.3MHz |
| 电流 - 输出： | 3A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 26-VFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 26-DFN（7x4） |
THEORY OF OPERATION
tures include thermal shutdown and short-cir-
cuit detection. In the event that either a thermal,
short-circuit, or UVLO fault is detected, the
SP7653 is forced into an idle state where the
output drivers are held off for a finite period
before a restart is attempted.
Thermal and Short-Circuit Protection
Because the SP7653 is designed to drive large
output current, there is a chance that the power
converter will become too hot. Therefore, an
internal thermal shutdown (145 ° C) has been
included to prevent the IC from malfunctioning
at extreme temperatures.
Soft Start
“Soft Start” is achieved when a power converter
ramps up the output voltage while controlling
the magnitude of the input supply source cur-
rent. In a modern step down converter, ramping
up the positive terminal of the error amplifier
controls soft start. As a result, excess source
current can be defined as the current required to
charge the output capacitor:
I VIN = C OUT * ( V OUT / T SOFT-START )
A short-circuit detection comparator has also
been included in the SP7653 to protect against
an accidental short at the output of the power
converter. This comparator constantly monitors
the positive and negative terminals of the error
amplifier, and if the V FB pin falls more than
250mV (typical) below the positive reference, a
short-circuit fault is set. Because the SS pin
overrides the internal 0.8V reference during soft
start, the SP7653 is capable of detecting short-
circuit faults throughout the duration of soft
start as well as in regular operation.
The SP7653 provides the user with the option to
program the soft start rate by tying a capacitor
from the SS pin to GND. The selection of this
capacitor is based on the 10uA pull up current
present at the SS pin and the 0.8V reference
voltage. Therefore, the excess source can be
redefined as:
IV IN = C OUT * [ (DV OUT *10 μ A) /(C SS * 0.8V) ]
Under Voltage Lock Out (UVLO)
The SP7653 contains two separate UVLO com-
parators to monitor the bias (V CC ) and conver-
sion (V IN ) voltages independently. The V CC
UVLO threshold is internally set to 4.25V,
whereas the V IN UVLO threshold is program-
mable through the UV IN pin. When the voltage
on the UV IN pin is greater than 2.5V, the SP7653
is permitted to start up pending the removal of
all other faults. Both the V CC and V IN UVLO
comparators have been designed with hysteresis
to prevent noise from resetting a fault.
Handling of Faults:
Upon the detection of power (UVLO), thermal,
or short-circuit faults, the SP7653 is forced into
an idle state where the SS and COMP pins are
pulled low and both switches are held off. In the
event of UVLO fault, the SP7653 remains in this
idle state until the UVLO fault is removed.
Upon the detection of a thermal or short-circuit
fault, an internal 200ms timer is activated. In the
event of a short-circuit fault, a restart is at-
tempted immediately after the 200ms timeout
expires. Whereas, when a thermal fault is de-
tected, the 200ms delay continuously recycles
and a restart cannot be attempted until the ther-
mal fault is removed and the timer expires.
Error Amplifier and Voltage Loop
The heart of the SP7653 voltage error loop
compensation is a high performance, wide band-
width transconductance amplifier. Because of
the amplifier’s current limited (+/-150 μ A)
transconductance, there are many ways to com-
pensate the voltage loop or to control the COMP
2/17/06
Date: /20/06
Wide Input Input Range,Range, BuckBuck
SP7653 SP7653 Wide Voltage Voltage .3MHz, 1.3MHz, Regulator
5 5
? Copyright 2006 Sipex Corporation
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相关代理商/技术参数 |
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