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RT8550 の電気的特性と機能

RT8550のメーカーはRichtekです、この部品の機能は「76V Boost DC/DC Converter」です。


製品の詳細 ( Datasheet PDF )

部品番号 RT8550
部品説明 76V Boost DC/DC Converter
メーカ Richtek
ロゴ Richtek ロゴ 




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RT8550 Datasheet, RT8550 PDF,ピン配置, 機能
®
RT8550
76V Boost DC/DC Converter with APD Current Monitor
General Description
The RT8550 is a high performance, low noise Boost DC/
DC converter with an integrated internal switch and an
avalanche photodiodes (APD) current monitor. The
RT8550's input voltage ranges from 2.8V to 5.5V, and it
can support the output voltage up to 76V. When used in
optical receiver application to drive the high voltage APD
diode, the output voltage of the RT8550 can be further
doubled up by a typical voltage doubler circuit. The RT8550
adapts fixed frequency, current mode PWM control loop
to regulate the output voltage with fast transient response
and cycle-by-cycle current limit. With 400kHz switching
frequency, the RT8550 system board can be made compact
to achieve low system BOM cost. The soft-start function
and PWM loop compensation is also built-in internally to
save external soft-start capacitor and PWM loop
compensation components. The RT8550 features accurate
APD current monitoring output with 5:1 ratio at the MON
pin. A Resistor-adjustable APD current limit function
protects the APD diode from Boost output transients. The
protection features of the RT8550 include input under-
voltage lockout and over temperature protection. The
RT8550 is available in the small and WQFN-16L 3x3
package.
Features
Input Voltage Range : 2.8V to 5.5V
Up to 76V Output Voltage
400kHz Fixed Switching Frequency
Internal Compensation and Soft-Start
APD Current Monitor within ±5% Tolerance
5:1 Ratio outputs for APD Current Monitoring
Low Shutdown Current : <1μA
Programmable APD Current Limit
RoHS Compliant and Halogen Free
Applications
APD Bias Supply
PIN Diode Bias Supply
Optical Receivers and Modules
Fiber Optic Network Equipment
GPON Modules
Marking Information
21= : Product Code
21=YM
DNN
YMDNN : Date Code
Simplified Application Circuit
L1 D1
VIN VOUT
CIN
RT8550
VIN SW
COUT
R2
RLIM
SHDN
RLIM
MONIN
FB
CTRL
R1
SGND
PGND
MON
APD
APD
TIA
R3
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8550-02 December 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

1 Page





RT8550 pdf, ピン配列
Function Block Diagram
SHDN
VIN
SW
SGND
CTRL
FB
1.22V
Reference
Soft-Start
2.4V
+
+ A1
-
Error
Amplifier
-
A2 R
+
PWM
Comparator
Q
S
+
Oscillator
-
Current
Sense
Amplifier
APD
Q1 Current
Mirror
APD
Current
Limit
PGND
RT8550
MON
MONIN
APD
RLIM
Operation
The RT8550 Boost converter uses a constant frequency
current mode control scheme to provide excellent line
and load regulation. Operation can be best understood
by referring to the Functional Diagram. At the start of each
oscillator cycle, the SR latch is set, which turns on the
power switch, Q1. A voltage proportional to the switch
current is added to a stabilizing ramp and the resulting
sum is fed into the positive terminal of the PWM
comparator, A2. When this voltage exceeds the level at
the negative input of A2, the SR latch is reset to turn off
the power switch. The level at the negative input of A2 is
set by the error amplifier A1, and is simply an amplified
version of the difference between the feedback voltage
and the reference voltage of 1.22V, or externally provided
CTRL voltage. In this manner, the error amplifier sets the
correct peak current level to keep the output in regulation.
If the error amplifier's output increases, more current is
delivered to the output; if it decreases, less current is
delivered.
The RT8550 has an integrated high-side APD current
monitor with a 5:1 ratio. The MONIN pin can accept a
supply voltage up to 76V, which is suitable for APD
photodiode applications. The MON pin has an open circuit
protection feature and is internally clamped to 2.4V. If an
APD is tied to the APD pin, the current will be mirrored to
the MON pin and converted to a voltage signal by the
resistor R3. This voltage signal can be used to drive an
external control block to adjust the APD voltage by
adjusting the feedback threshold of EAMP A1 through the
CTRL input. The RT8550 also integrates an internal clamp
circuit for the MON pin with clamp level around 2.4V.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8550-02 December 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3


3Pages


RT8550 電子部品, 半導体
RT8550
Typical Application Circuit
VIN
2.8V to 5.5V
L1
22µH
D1
CIN
1µF
2 VIN
RT8550
SW 14, 15
RLIM
4.7k
3 SHDN
9 RLIM
MONIN 13
FB 5
CTRL 6
8 SGND
MON 10
1, 16,
17 (Exposed Pad)
PGND
APD
APD 12
TIA
COUT
0.1µF
VOUT
76V (Max)
R2
360k
RADJ
R1
6.2k
GPIO DAC
µC
R3
10k
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
6
is a registered trademark of Richtek Technology Corporation.
DS8550-02 December 2014

6 Page



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共有リンク

Link :


部品番号部品説明メーカ
RT8550

76V Boost DC/DC Converter

Richtek
Richtek
RT8553A

Dual-Output Synchronous DC/DC Converter

Richtek
Richtek


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