参数资料
型号: IR3853MTR1PBF
厂商: International Rectifier
文件页数: 18/35页
文件大小: 0K
描述: IC REG BUCK SYNC ADJ 4A PQFN17
产品培训模块: SupIRBuck? Family and POL Design Tools Overview
标准包装: 1
系列: SupIRBuck™
类型: 降压(降压)
输出类型: 可调式
输出数: 1
输出电压: 0.7 V ~ 18.9 V
输入电压: 1.5 V ~ 21 V
PWM 型: 电压模式
频率 - 开关: 225kHz ~ 1.65MHz
电流 - 输出: 4A
同步整流器:
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: 17-PowerVQFN
包装: 标准包装
供应商设备封装: 17-PQFN(4x5)
其它名称: IR3853MTR1PBFDKR
PD-97516
IR3853MPbF
Minimum on time Considerations
The minimum ON time is the shortest amount of
time for which the Control FET may be reliably
turned on, and this depends on the internal
timing delays. For the IR3853, the typical
minimum on-time is specified as 50 ns.
Any design or application using the IR3853 must
ensure operation with a pulse width that is higher
than this minimum on-time and preferably higher
than 100 ns. This is necessary for the circuit to
operate without jitter and pulse-skipping, which
can cause high inductor current ripple and high
output voltage ripple.
Maximum Duty Ratio Considerations
A fixed off-time of 200 ns maximum is specified
for the IR3853. This provides an upper limit on
the operating duty ratio at any given switching
frequency. It is clear, that higher the switching
frequency, the lower is the maximum duty ratio at
which the IR3853 can operate. To allow a margin
of 50ns, the maximum operating duty ratio in any
application using the IR3853 should still
accommodate about 250 ns off-time. Fig 10.
shows a plot of the maximum duty ratio v/s the
switching frequency, with 250 ns off-time.
t on =
=
D
F s
V out
V in × F s
95
90
85
80
75
M a x Duty Cycle
In any application that uses the IR3853, the
following condition must be satisfied:
70
65
60
55
∴ t on (min) ≤
t on (min) ≤ t on
V out
V in × F s
250 450 650 850 1050 1250 1450
S w itchin g Freq uency (kH z )
Fig. 11. Maximum duty cycle v/s switching
1650
∴ V in × F s ≤
V out
t on (min)
frequency.
The minimum output voltage is limited by the
reference voltage and hence V out(min) = 0.7 V.
Therefore, for V out(min) = 0.7 V,
∴ V in × F s ≤
∴ V in × F s ≤
V out (min)
t on (min)
0.7 V
100 ns
= 7 × 10 6 V/s
Therefore, at the maximum recommended input
voltage 21V and minimum output voltage, the
converter should be designed at a switching
frequency that does not exceed 333 kHz.
Conversely, for operation at the maximum
recommended operating frequency 1.65 MHz
and minimum output voltage, any voltage above
4.2 V may not be stepped down without pulse-
skipping.
Rev 4.0
18
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参数描述
IR3853MTR1PBF 制造商:International Rectifier 功能描述:IC DC-DC CONV 1.5 MHz QFN-17
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