LM34927_15 Datasheet, PDF (1/28 Pages) Texas Instruments – LM34927 Integrated Secondary-Side Bias Regulator for Isolated DC-DC Converters

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LM34927
SNVS799G – APRIL 2012 – REVISED DECEMBER 2014
LM34927 Integrated Secondary-Side Bias Regulator for Isolated DC-DC Converters
1 Features
•1 Wide 7.5-V to 100-V Input Range
• Integrated 600-mA High-Side
and Low-Side Switches
• No Schottky Required
• Constant On-Time Control
• No Loop Compensation Required
• Ultra-Fast Transient Response
• Nearly Constant Operating Frequency
• Intelligent Peak Current Limit
• Adjustable Output Voltage From 1.225 V
• Precision 2% Feedback Reference
• Frequency Adjustable to 1 MHz
• Adjustable Undervoltage Lockout (UVLO)
• Remote Shutdown
• Thermal Shutdown
• Packages:
– WSON-8
– SO PowerPAD™-8
2 Applications
• Isolated Telecom Bias Supply
• Isolated Automotive and Industrial Electronics
3 Description
The LM34927 regulator features all of the functions
needed to implement a low-cost, efficient, isolated
bias regulator. This high-voltage regulator contains
two 100-V N-channel MOSFET switches — a high-
side buck switch and a low-side synchronous switch.
The Constant on-time (COT) control scheme
employed in the LM34927 device requires no loop
compensation and provides excellent transient
response. The regulator operates with an on-time that
is inversely proportional to the input voltage. This
feature allows the operating frequency to remain
relatively constant. An intelligent peak current limit is
implemented with integrated sense circuit. Other
features include a programmable input undervoltage
comparator to inhibit operation during low-voltage
conditions. Protection features include thermal
shutdown and V_CC Undervoltage Lockout (UVLO).
The LM34927 device is offered in WSON-8 and SO
PowerPAD-8 plastic packages.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LM34927
SO PowerPAD (8)
WSON (8)
4.89 mm x 3.90 mm
4.00 mm x 4.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
VIN
9V-100V
+
C_IN
R_UV2
R_UV1
Typical Application
D1
VOUT2
R_ON
LM34927
7
2
BST
V_IN
4 _RON
SW ⁸
3 _UVLO
VCC ⁶
FB ⁵
RTN
1
+
N_S
C_OUT2
+
C_BST
X1
N_P
VOUT1
D2
+
C_VCC
R_FB2
R_FB1
R_r
+
C_OUT1
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.