SI9122A_08 VISHAY [Vishay Siliconix], SI9122A_08 Datasheet

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SI9122A_08

Manufacturer Part Number
SI9122A_08
Description
500-kHz Half-Bridge DC/DC Controller with Integrated Secondary Synchronous Rectification Drivers
Manufacturer
VISHAY [Vishay Siliconix]
Datasheet
DESCRIPTION
Si9122A is a half-bridge controller IC ideally suited to fixed
telecom applications where high efficiency is required at low
output voltages (e.g. < 3.3 V). Designed to operate within the
fixed telecom voltage range of 33 V to 75 V and withstand
100 V, 100 ms transients, the IC is capable of controlling and
driving both the low and high-side switching devices of a half
bridge circuit and also controlling the switching devices on
the secondary side of the bridge. Due to the very low on-
resistance of the secondary MOSFETs, a significant
increase in conversion efficiency can be achieved as
compared with conventional Schottky diodes. Control of the
secondary devices is by means of a pulse transformer and a
pair of inverters. Such a system has efficiencies well in
excess of 90 % even for low output voltages. On-chip control
of the dead time delays between the primary and secondary
synchronous signals keep efficiencies high and prevent
accidental destruction of the power transformer. An external
resistor sets the switching frequency from 200 kHz to
625 kHz.
Si9122A has advanced current monitoring and control
circuitry which allow the user to set the maximum current in
the primary circuit. Such a feature acts as protection against
output shorting and also provides constant current into large
capacitive loads during start-up or when paralleling power
supplies. Current sensing is by means of a sense resistor on
the low-side primary device.
FUNCTIONAL BLOCK DIAGRAM
Document Number: 73492
S-80038-Rev. D, 14-Jan-08
28 V to 75 V
with Integrated Secondary Synchronous Rectification Drivers
V
C
IN_DET
L_CONT
500-kHz Half-Bridge DC/DC Controller
Si9122A
SR
SR
BST
CS2
CS1
DH
DL
EP
LX
H
L
Figure 1.
FEATURES
APPLICATIONS
• 28 V to 75 V input voltage range
• Compatible with ETSI 300 132-2
• Integrated ± 1 A half-bridge primary drivers
• Secondary synchronous rectifier control
• Voltage mode control
• Voltage feedforward compensation
• High voltage pre-regulator operates during start-up
• Current sensing on low-side primary device
• Frequency foldback eliminates constant current tail
• Advanced maximum current control during start-up and
• Low input voltage detection
• Programmable soft-start function
• Over temperature protection
• Network cards
• Power supply modules
signals with programmable deadtime delay
shorted load
Synchronous
Rectifiers
V
CC
Opto Isolator
Vishay Siliconix
Amplifier
Error
1 V to 12 V Typ.
Si9122A
www.vishay.com
+
-
V
RoHS
V
COMPLIANT
REF
OUT
+
1

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SI9122A_08 Summary of contents

Page 1

Half-Bridge DC/DC Controller with Integrated Secondary Synchronous Rectification Drivers DESCRIPTION Si9122A is a half-bridge controller IC ideally suited to fixed telecom applications where high efficiency is required at low output voltages (e.g. < 3.3 V). Designed to operate within ...

Page 2

Si9122A Vishay Siliconix TECHNICAL DESCRIPTION Si9122A is a voltage mode controller for the half-bridge topology. With 100 V depletion mode MOSFET capability, the Si9122A is capable of powering directly from the high voltage bus to V through an external PNP ...

Page 3

ABSOLUTE MAXIMUM RATINGS Parameter V (Continuous (100 ms BST BST REF OSC Logic Inputs Analog Inputs HV Pre-Regulator Input Current (Continuous) Storage Temperature Operating Junction ...

Page 4

Si9122A Vishay Siliconix a SPECIFICATIONS Parameter Symbol Reference (3 Output Voltage I Short Circuit Current SREF Load Regulation dVr/dir Power Supply Rejection PSRR Oscillator Accuracy ( OSC h F Max Frequency d F Foldback Frequency ...

Page 5

SPECIFICATIONS Parameter Symbol Pre-Regulator V V Pre-Regulator Turn Off REG1 CC Threshold Voltage V REG2 V Undervoltage Lockout UVLO Hysteresis UVLOHYS UVLO Soft-Start I Soft-Start Current Output V Soft-Start Completion Voltage SS_COMP Shutdown V Shutdown V ...

Page 6

Si9122A Vishay Siliconix a SPECIFICATIONS Parameter Symbol Synchronous Rectifier (SRH, SRL) Drivers V Output High Voltage V Output Low Voltage t BBM1 t BBM2 f Break-Before-Make Time t BBM3 t BBM4 I Peak Output Source SOURCE I Peak Output Sink ...

Page 7

TIMING DIAGRAM FOR MOS DRIVERS V CC PWM GND GND GND V BST V MID D H GND V CC GND t t BBM1 BBM2 ...

Page 8

Si9122A Vishay Siliconix PIN CONFIGURATION Si9122ADQ (TSSOP-20 REG_COMP REF GND OSC INDET CS1 9 CS2 10 Top View ORDERING INFORMATION Part Number Si9122ADQ-T1-E3 Si9122ADLP-T1-E3 ...

Page 9

Bandgap V Reference REF 3 INDET C L_CONT Voltage Frequency Feedforward Foldback R OSC OSC Oscillator Clock 132 kΩ 60 kΩ REF Current Gain Control CS2 Loop + - Control CS1 100 mV ...

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Si9122A Vishay Siliconix Care needs to be taken if there is a delay prior to the external circuit feeding back to the V supply. To prevent excessive CC power dissipation within the advisable to use an external ...

Page 11

Current Limit Current mode control providing constant current operation is achieved by monitoring the differential voltage V the CS1 and CS2 pins, which are connected to a current sense resistor on the primary low-side MOSFET. In the absence of an ...

Page 12

Si9122A Vishay Siliconix TYPICAL CHARACTERISTICS 600 500 400 300 200 (kΩ) OSC f vs OSC OSC 10.0 9.5 9 mV/C 8.5 8.0 7 ...

Page 13

TYPICAL CHARACTERISTICS Temperature (°C) I vs. Temperature REG2 250 200 CC 150 100 200 400 V (mV ...

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Si9122A Vishay Siliconix TYPICAL CHARACTERISTICS 100 (kΩ) BBM t vs BBM BBM BBM1 ...

Page 15

TYPICAL CHARACTERISTICS BBM1 BBM2 BBM2 3.5 4.5 5.5 V (V) INDET t vs. V ...

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Si9122A Vishay Siliconix TYPICAL WAVEFORMS SRL 10 V/div /div OUT D 10 V/div L CS2 50 mV/div 2 µs/div Figure 7. Foldback Mode V/div V/div CC 2 ms/div Figure 9. V ...

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TSSOP: 20-LEAD (POWER IC ONLY E 1.00 DIA. 1.00 (14_) 0. ∝ 1.00 (14_) DETAIL ‘A’ (SCALE: 30/1) (VIEW ROTATED 90_ C.W.) e ...

Page 18

PowerPAKr MLP65-18/20 (POWER IC ONLY) D D/2 -A- E/2 E Index Area D/2 E/2 TOP VIEW A // ccc C 0. e/2 Terminal Tip e 5 EVEN TERMINAL SIDE DETAIL B Document Number: 73182 15-Oct-04 Index Area ...

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Package Information Vishay Siliconix PowerPAK MLP65-18/20 (POWER IC ONLY 18/20 PITCH: 0.5 mm, BODY SIZE: 6.00 x 5.00 MILLIMETERS* Dim Min A 0.80 A1 0.00 A2 0.00 A3 aaa − b 0.18 bbb − C’ − ccc − ...

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... Parameters provided in datasheets and/or specifications may vary in different applications and performance may vary over time. All operating parameters, including typical parameters, must be validated for each customer application by the customer’s technical experts. Product specifications do not expand or otherwise modify Vishay’ ...

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