ÿ Step down converter, for external FET E910.28

Introduction
bus ic
dc/dc converter
motor driver ic
ripple counter
driver ic
I/O ic
Sensor interface ic
sensor ic
ip’s
E 910.22 Wide range flyb. SMPS with WD
E 910.24 | 25 | 26 PFM controller family
E 910.27 Step down converter, fully integr.
E 981.03 Energy storage controller
ÿ E 910.28 Step down converter, for ext. FET
features
application
ÿ Wide input range of 5V to 60V
ÿ Automotive electronics
ÿ Wide, adjustable output voltage of 1.25V to (Vin-0.5V)
ÿ Controller and sensor supply
ÿ Output current range of 0mA to > 10A depending ÿ LED supply
ÿ General supply applications
only on external PFET
pinning
Pin
ÿ Supports optional external NFET as free wheeling diode
ÿ Very high efficiency over load current range
description
ÿ Very low shutdown current with internal supply off The IC is developed and optimized for automotive applications
(20µA typical)
where it can be used to supply controllers, sensors, Power-LEDs
ÿ Low standby current with internal supply on for fast and many other devices. The reference input allows it to control
start up (<200µA typical)
the output voltage (or current) with e.g. an external DAC. That
ÿ 100% duty cycle possible
makes it easy to build LED-dimmer or any application that needs
ÿ Easy to use chaotic regulation behaviour
variable supply.
ÿ Fast multi-loop-regulation
ÿ Adaptive frequency selection up to 300kHz
For fast load and line regulation a multi-loop regulation is imple-
ÿ No compensation necessary
mented using a chaotic current mode regulator that even requires
ÿ External reference voltage input, for e.g.
no compensation components. A duty cycle of 100% enables the
DAC control of Vout
minimum possible voltage drop and therefore the best utilization
ÿ ON and Sleep control-input with TTL/CMOS
of components and input voltage range. Due to the external FETs
threshold but accepting up to 60V
any required power can be realised. The option to have an NFET as
ÿ Open load stable
a free wheeling diode help increases the system efficiency. With
ÿ Temperature range – 40°C to + 125 ºC
the ON and SLP pins the converter can be started and stopped.
ÿ TSSOP24 package
Due to their wide input voltage range the pins can be driven with
TTL- and CMOS-level as well as CAN-controller output or a (filtered) Kl15-signals.
package
Name
Description
1
RSEN
PFM current sense comparator input
RSEN
1
24
LGT
2
CLDR
Supply rail input
CLDR
2
23
UPG
3
CHDR
High side linear regulator output
CHDR
3
22
PGND
4
VS
Positive analog and power stage supply input
VS
4
21
GND
LXT
5
20
CDLY
5
LXT
Zero crossing detection
ENPS
6
19
PWGD
6
ENPS
Shutdown input
SMON
7
18
WDI
VSM
8
17
WEN
7
SMON
Active-high SMON control input
SGND
9
16
RSEL
8
VSM
Internal linear regulator output
AGND
10
15
RLEV
VFB
11
14
SDLY
9
SGND
Signal ground
RFEX
12
13
LSDIS
10
AGND
Analog ground
11
VFB
Feedback input
12
RFEX
External reference input
13
LSDIS
Low side N-channel FET driver is active
14
SDLY
Delayed restart PFM after fault, high-active
15
RLEV
Internal high-reference low active
16
RSEL
Reference select, low=internal, high=external
17
WEN
Watchdog enable input
18
WDI
Watchdog trigger input
19
PWGD
Open drain output
20
CDLY
Delay timing capacitor
21
GND
Ground
22
PGND
Power ground
23
UPG
Gate driver for external high-side P-channel FET
24
LGT
Gate driver for external low-side N-channel FET
TSSOP24
ÿ
ÿ
E910.28
ÿ THIS PRODUCT IS UNDER DEVELOPMENT
THIS PRODUCT IS UNDER DEVELOPMENT
ÿ Step down converter, for external FET THIS PRODUCT IS UNDER DEVELOPMENT
Block diagram
VBAT
VS
LXT
CHDR
VLIM
SMON
int.
ENPS
Supply
VSM
RSEN
VS
UPG
CLDR
RFEX
CHDR
0,2 V
1,22 V
PWM
VCMP
MUX
GEN
Vout
ANTSHT
RSEL
CLDR
LGT
RLEV
PWGD
WDI
WEN
PowerGood
&
WD
E910.28
CDLY
36
VFB
GND
SDLY
LSDIS
PGND
Note ELMOS Semiconductor AG (below ELMOS) reserves the right to make changes to the product contained in this publication without notice. ELMOS assumes no responsibility for the use of any
circuits described herein, conveys no licence under any patent or other right, and makes no representation that the circuits are free of patent infringement. While the information in this publication
has been checked, no responsibility, however, is assumed for inaccuracies. ELMOS does not recommend the use of any of its products in life support applications where the failure or malfunction of
the product can reasonably be expected to cause failure of a life-support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications.
Copyright © 2007 ELMOS Reproduction, in part or whole, without the prior written consent of ELMOS, is prohibited.
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elmos product catalog 2007/2008
37