UC2856Q

Manufacturer Part NumberUC2856Q
DescriptionThe UC2856 is a high performance version of the popular UC2846 series of current mode controllers, and is intended for both design upgrades and new applications where speed and accuracy are important
ManufacturerTexas Instruments
UC2856Q datasheet
 


Specifications of UC2856Q

TopologyBoost, Flyback, Forward, Full-Bridge, Half-Bridge, Push-PullControl MethodCurrent
Duty Cycle(max)(%)50Frequency(max)(khz)1000
Uvlo Thresholds On/off(v)7.7Pin/package16SOIC
Vin(min)(v)8Vin(max)(v)40
Regulated Outputs(#)2Operating Temperature Range(c)-40 to 125
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IMPROVED CURRENT MODE PWM CONTROLLER
FEATURES
1
Pin-for-Pin Compatible With the UC2846
65-ns Typical Delay From Shutdown to
Outputs and 50-ns Typical Delay From
Sync to Outputs
Improved Current Sense Amplifier With
Reduced Noise Sensitivity
Differential Current Sense With 3-V
Common Mode Range
Trimmed Oscillator Discharge Current for
Accurate Deadband Control
Accurate 1-V Shutdown Threshold
High Current Dual Totem Pole
Outputs (1.5-A peak)
TTL Compatible Oscillator SYNC Pin
Thresholds
4-kV ESD Protection
DESCRIPTION
The UC2856 is a high performance version of the popular UC2846 series of current mode controllers, and is
intended for both design upgrades and new applications where speed and accuracy are important. All input to
output delays have been minimized, and the current sense output is slew rate limited to reduce noise sensitivity.
Fast 1.5-A peak output stages have been added to allow rapid switching of power FETs.
A low impedance TTL compatible sync output has been implemented with a 3-state function when used as a
sync input.
Internal chip grounding has been improved to minimize internal noise caused when driving large capacitive
loads. This, in conjunction with the improved differential current sense amplifier, results in enhanced noise
immunity.
Other features include a trimmed oscillator current (8%) for accurate frequency and dead time control; a 1 V, 5%
shutdown threshold; and 4 kV minimum ESD protection on all pins.
T
A
–40°C to 125°C
(1) Package drawings, standard packing quantities, thermal data, symbolization, and PCB design
guidelines are available at www.ti.com/sc/package.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Check for Samples:
UC2856Q
CL SS
VREF
CS−
CS+
EA+
EA−
COMP
CT
ORDERING INFORMATION
ORDERABLE
PACKAGE
PART NUMBER
SOP–DW
Tape and reel
UC2856QDWR
UC2856Q
SGLS265A – NOVEMBER 2004 – REVISED MAY 2011
DW PACKAGE
(TOP VIEW)
1
16
SHUTDOWN
2
15
VIN
3
14
BOUT
4
13
VC
5
12
GND
6
11
AOUT
7
10
SYNC
8
9
RT
(1)
TOP-SIDE
MARKING
UC2856Q
Copyright © 2004–2011, Texas Instruments Incorporated
P0008-01

UC2856Q Summary of contents

  • Page 1

    ... Tape and reel UC2856QDWR UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 DW PACKAGE (TOP VIEW SHUTDOWN 2 15 VIN 3 14 BOUT GND 6 11 AOUT 7 10 SYNC (1) TOP-SIDE MARKING UC2856Q Copyright © 2004–2011, Texas Instruments Incorporated P0008-01 ...

  • Page 2

    ... UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. VIN 15 SYNC 4.1 V CS− ...

  • Page 3

    ... VREF VREF VREF SYNC VREF 0 SYNC UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 UNIT 0 –0 VIN –0 –0 ±10 mA ...

  • Page 4

    ... UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 ELECTRICAL CHARACTERISTICS (continued –40°C to 125°C, VIN = kΩ nF, and T A PARAMETER ERROR AMPLIFIER SECTION Input offset voltage Input bias current Input offset current Common mode range Open loop gain ...

  • Page 5

    ... UNDERVOLTAGE LOCKOUT SECTION Startup threshold Threshold hysterisis TOTAL STANDBY CURRENT Supply current Copyright © 2004–2011, Texas Instruments Incorporated SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 ( (unless otherwise stated TEST CONDITIONS MIN 45% UC2856Q TYP MAX UNIT 47% 50% 0% 7 ...

  • Page 6

    ... UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 APPLICATION AND OPERATION INFORMATION V REF COMP SYNC NOTE: Output deadtime is determined by the size of the external capacitor, C For large values 250 C T Oscillator frequency is approximated by the formula: NOTE: Error Amplifier can source up to 0.5 mA. ...

  • Page 7

    ... R − Output Load Resistance − Master SYNC COMP EA− SYNC COMP EA− Slave (Additional Units) Figure 5. Parallel Operation UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 G002 Output V OUT Filters S0021-01 7 ...

  • Page 8

    ... UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 I S (+) R (− REF R1 R2 NOTE: Peak current ( determined by the formula: S Figure 6. Pulse by Pulse Current Limiting SENSE 3 − 0 0.5 mA Current Limit 1 V REF R2 * 0.5 R1) www.ti.com COMP EA 7 COMP S0022-01 Copyright © ...

  • Page 9

    ... Copyright © 2004–2011, Texas Instruments Incorporated I SENSE + Current Limit SHUTDOWN 16 + − 1 0.8 mA and a restart cycle will be initiated Figure 7. Shutdown UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 COMP S − 0 REF SHUTDOWN Without Auto-Restart (Latched) S0023-01 / REF 9 ...

  • Page 10

    ... UC2856Q SGLS265A – NOVEMBER 2004 – REVISED MAY 2011 Changes from Original (November 2004) to Revision A • Changed the polarity of the comparator connected to pin REVISION HISTORY Figure 7 ............................................................................ Copyright © 2004–2011, Texas Instruments Incorporated www.ti.com Page 9 ...

  • Page 11

    ... PACKAGING INFORMATION Orderable Device (1) Package Type Package Status UC2856QDWR ACTIVE SOIC (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. ...

  • Page 12

    ... TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Type Drawing UC2856QDWR SOIC DW PACKAGE MATERIALS INFORMATION Pins SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 16 2000 330.0 16.4 10.85 Pack Materials-Page 1 25-May-2011 Pin1 (mm) (mm) (mm) (mm) Quadrant 10.8 2.7 12.0 16.0 Q1 ...

  • Page 13

    ... Device Package Type UC2856QDWR SOIC PACKAGE MATERIALS INFORMATION Package Drawing Pins SPQ Length (mm 2000 Pack Materials-Page 2 25-May-2011 Width (mm) Height (mm) 346.0 346.0 33.0 ...

  • Page 14

    ...

  • Page 15

    ... Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’ ...