LM34926 Datasheet, PDF (1/28 Pages) Texas Instruments – LM34926 Integrated Secondary-Side Bias Regulator for Isolated DC-DC Converters

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LM34926
SNVS847E – JUNE 2012 – REVISED DECEMBER 2014
LM34926 Integrated Secondary-Side Bias Regulator for Isolated DC-DC Converters
1 Features
•1 Wide 7.5-V to 100-V Input Range
• Integrated 300-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 Packages
2 Applications
• Isolated Telecom Bias Supply
• Isolated Automotive and Industrial Electronics
3 Description
The LM34926 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 LM34926 requires no loop
compensation and provides excellent transient
response. The regulator operates with an on-time
control 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 LM34926 device is offered in WSON-8
and SO PowerPAD-8 plastic packages.
Device Information⁽¹⁾
PART NUMBER PACKAGE
BODY SIZE (NOM)
LM34926
HSOP (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
7.5V-100V
+
C_IN
R_UV2
R_UV1
Typical Application
D1
VOUT2
LM34926
7
+
N_S
C_OUT2
2
V_IN
4
RON
BST
+
SW ⁸
C_BST
X1
N_P
VOUT1
R_ON
3
UVLO
6
VCC
FB ⁵
RTN
1
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.