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RT8541 の電気的特性と機能

RT8541のメーカーはRichtekです、この部品の機能は「Boost DC/DC Converter」です。


製品の詳細 ( Datasheet PDF )

部品番号 RT8541
部品説明 Boost DC/DC Converter
メーカ Richtek
ロゴ Richtek ロゴ 




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RT8541 Datasheet, RT8541 PDF,ピン配置, 機能
®
RT8541/A
90V Boost DC/DC Converter with APD Current Monitor
General Description
The RT8541/A is a constant frequency current mode PWM
step-up DC/DC converter designed to bias avalanche
photodiodes (APD) at high voltage in optical receivers. It
includes a voltage doubler charge pump to significantly
reduce the noise level at output up to 90V. The RT8541A
switching frequency can be adjusted by a resistor while
RT8541 is internally set at 650kHz. The RT8541/A has a
built-in APD current mirror that delivers 1/5 of the APD
current with high accuracy for monitoring the APD current
from 0.25μA to 2.5mA. This current can be used as a
reference to provide a digital programmed output voltage
via the CTRL pin. To protect the optical receiver system,
the RT8541/A provides a built-in adjustable APD current
limit function by sensing a 200mV voltage threshold
between VOUT2 and MONIN pins. Only one resistor is
needed to program the desired current limit. A charge pump
voltage doubler is designed to achieve significantly lower
noise level at the APD comparing to a simple boost
converter type bias circuit.
The RT8541/A also features a built-in 9ms soft-start
function to eliminate the inrush current during start-up
interval. The RT8541/A provides a low cost optical receiver
solution and can fit in very small PCB area.
The RT8541/A is available in the WQFN-16L 3x3 package.
Features
Integrated Schottky Diodes for Charge Pump
Voltage Doubler
50V, 400mA Internal Switch
High Side Low Noise and Accurate APD Current
Monitor
650kHz Fixed Switching Frequency for RT8541 and
Adjustable Switching Frequency for RT8541A
Wide VIN Range : 2.7V to 16V
Adjustable APD Current Limit with External Resistor
Low Shutdown Current <1μA
Built-In Soft-Start
CTRL Pin Allows Output Adjustment with no Polarity
Inversion
Thin 16-Lead WQFN Package
RoHS Compliant and Halogen Free
Applications
APD Bias
PIN Diode Bias
Optical Receivers and Modules
Fiber Optic Network Equipment
Simplified Application Circuit
L C1
VIN
CIN
SW PUMP
VIN RT8541/A
R5
CTRL
MONIN
SHDN
VOUT2
VC
R4
FSET
VOUT1
RSET
C4
GND
FB
MON
APD
R6
C2
C3
CFB R2
VOUT
COUT
R1
R3
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
DS8541/A-01 June 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

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RT8541 pdf, ピン配列
RT8541/A
Functional Pin Description
Pin No.
Pin Name
Pin Function
1 VC Compensation Node for Control Loop.
2
APD
Output for APD. Connect this Pin to the APD Cathode.
3
MONIN
Current Monitor Input Power Pin. An optional resistor between the VOUT2 and
MONIN pins can be used for current limit setting.
Voltage Doubler Output Pin. A 50V rated capacitor is needed between this pin
4
VOUT2
and VOUT1 pin. A resistor divider for output voltage feedback is connected
between this pin and GND pin.
5
VOUT1
Output Pin of Boost Converter. A capacitor is needed between this pin and
GND pin. The trace length from this pin to the capacitor should be minimized.
Charge Pump Pin for Voltage Doubler. Put a 50V capacitor between the SW
6
PUMP
and PUMP pins to form a complete voltage doubler with the internal Schottky
diodes.
7, 8 SW
Switch Node of Boost Converter. Minimize the trace area on this pin to reduce
EMI. A Schottky diode between SW pin (cathode) and GND pin (anode) is
required
9, 10,
17 (Exposed Pad)
GND
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
11 VIN Supply Voltage Input. Connect a 1F capacitor from this pin to GND.
12
SHDN
Shutdown Control Input. Tie to 2V or higher with a resistor 200kto enable
device.
External Reference Control Input. This allows the FB voltage to follow the
13
CTRL
external reference between 0V and 1.2V. Tie this pin higher than 1.5V to use
the internal reference of 1.235V.
14 FB
Feedback Input. Connect the pin to the output resistor divider for output voltage
setting.
NC
(RT8541)
No Internal Connection. The switching frequency is set at 650kHz internally.
15
FSET
Oscillator Frequency Setting. Connect a resistor between this pin and GND for
(RT8541A) frequency setting.
16
MON
Output for Current Monitor. It sources a current equal to 20% of the APD
current and converts to a reference voltage through an external resistor.
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
DS8541/A-01 June 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3


3Pages


RT8541 電子部品, 半導体
RT8541/A
Parameter
Symbol
Test Conditions
Min Typ Max Unit
SHDN Voltage High
SHDN Voltage Low
SHDN Pin Bias Current
Internal Soft-Start Time
VIH
VIL
2 -- -- V
-- -- 0.4 V
-- 1 2 A
-- 9 -- ms
VC Threshold Voltage
APD Current Monitor Gain
GAPD
Monitor Output Voltage Clamp
APD Monitor Voltage Drop
MONIN Pin Current Limit
Threshold Voltage
CTRL to FB Offset
OTP Threshold Temperature
-- 0.7 --
IAPD = 250nA, 10V MONIN 90V 0.18 0.2 0.22
IAPD = 2.5mA, 20V MONIN 90V 0.18 0.2 0.22
MONIN APD at IAPD = 1mA,
MONIN = 90V
-- 15 16
-- -- 5
V
--
V
V
APD = 0V, MONIN = 40V
-- 200 -- mV
CTRL = 0.5V
5 2 12 mV
--150 -- C
Note 1. Stresses beyond those listed Absolute Maximum Ratingsmay cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
measured at the exposed pad of the package.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
www.richtek.com
6
is a registered trademark of Richtek Technology Corporation.
DS8541/A-01 June 2015

6 Page



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共有リンク

Link :


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