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U6229B
DC/DC Converter - Power Supply 28 V
Description
The U6229B is a multifunctional power supply IC which provides four different voltages dedicated to supply components of complex microcontroller systems. Supplied by a battery voltage in the wide range from 6 V to 26 V, the U6229B generates typically 28.4 V with a step-up converter, PWM, external power MOSFET and 150 mH inductivity. This voltage is fed to a step-down converter with external 150 mH inductivity to generate a 7-V auxiliary voltage with a small ripple. By means of this voltage, two linear regulators with only a small power dissipation provide a constant 5-V (3%) supply for microcontrollers and an even more accurate 5-V (2%) supply as a reference for sensors and a/d converters.
Features
D Voltage outputs
- - - - 28.4-V step-up converter with I 1.2 A 7-V step-down converter with I mA 5-V logic supply with I mA 5-V reference voltage with I mA
D Logic input ENABLE
v v400 v14 v14
D Analog input VKL15
- Energy-reserve mode switches off the step-up converter at VBatt < 5.25 V - Controls start-up behavior
D Logic output NRES
- N-reset output with over/ under voltage monitoring of both 5-V supplies
- Enables the step-up converter
Ordering Information
Extended Type Number U6229B Package SO20 Remarks
Block Diagram
VBatt 28.4 V Supply 7V Supply 5V Logic supply 5V Reference supply
VBL
VA1
VHL VH
VCC
VREF
GATE
Step-down converter PWM Step-up converter Logic supply Reference voltage
SOURCE
SGND
VKL15
Start-up circuit and over voltage protection
GND ENABLE
Oscillator
Internal reference
Over / under voltage control VCC / VREF
AGND NRES
96 12284
OSC
RSET
Figure 1. Block diagram with external circuit
Rev. A1, 21-Apr-99
1 (8)
Preliminary Information
U6229B
Pin Description
Pin 1 2 3 4 5, 6, 15, 16, 17 7 8 9 10 11 12 13 14 18 19 20 Symbol OSC VBL VA1 SOURCE SGND GATE VHL VH VCC VREF NRES ENVA3 VKL15 AGND RSET1 GND Input / Output Analog input Analog input Analog output Analog input Ground Analog output Analog input Analog output Analog output Analog output Logic output Logic input Analog input Ground Analog input Ground Function Oscillator Input set-up converter Output set-up converter Source of switching transistor Ground Gate of switch transistor Output of power switch step-down converter Regulator input step-down converter 5-V supply voltage 5-V reference voltage Power-on reset Control step-up converter Monitoring supply voltage Reference ground Connect external resistor to GND - bias of the current sources Ground
OSC VBL VA1
SOURCE
1 2 3 4 5 6 7 8 9 10
20
GND
Functional Description
Oscillator, Pin 1
The switching frequency fosc is defined with (as) a triangle oscillator and is programmed with the capacitor COS1. fosc = Kosc/COS1
19 RSET1 18 AGND 17 SGND 16 SGND 15 SGND 14 VKl15 13 ENVA3 12 NRES 11 VREF
SGND SGND GATE VHL VH VCC
Step-up Converter VBL Pin 2, VA1 Pin 3
The step-up converter uses the battery voltage (6V to 26 V) to produce a constant output voltage (VA1 typ. 28.4 V). An external power MOSFET serves as the electronic power switch of the step-up converter. When this switch is activated, the coil current increases up to a limit determined by the controller. The power MOSFET is switched off when this limit is reached, and the energy stored in the coil is discharged into the capacitance CVA1 via the diode and the switches between VBL and VA1. The maximum possible coil current is limited to typ. 1.2 A by the circuit.
Figure 2. Pinning U6229B
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Rev. A1, 21-Apr-99
Preliminary Information
U6229B
VBatt VA1
VKL15 VBL fosc Load-dump protection VAI PWM VH VHL
PWM
GATE SOURCE
CVA1
96 12289
CVH
96 12288
Figure 4. Basic principle of the step-down converter
Figure 3. Basic principle of the step-up converter
VCC, Pin 10
Output VCC supplies a 5-V voltage suitable for powering systems with microcontroller. The linear controller producing this voltage obtains its supply voltage from the voltage (VH) provided by the step-down converter. VCC is continuously monitored for any overvoltage or undervoltage. If such conditions occur, Pin NRES is switched to 'Low' for this time. VREF is deactivated simultaneously.
SOURCE, Pin 4
A shunt resistor (typ. 180 mW) is connected between the SOURCE pin and SGND for measurement of the coil current of the step-up converter.
SGND, Pins 5, 6, 15, 16 and 17
SGND is the power ground for the step-up and step-down converter. These pins are at the same time metallically connected to the chip carrier. This results in a very low thermal resistance of the package, which can be significantly improved by further external measures (large copper areas or heat sink/metal housing near these pins).
VREF, Pin 11
Output VREF supplies a precise output voltage of 5V (+/- 2%) (suitable, for example, as a reference voltage for an analog-to-digital converter). The linear controller producing this voltage obtains its supply voltage from the voltage (VH) provided by the step-down converter. VCC is continuously monitored for any overvoltage or undervoltage. If such conditions occur, Pin NRES is switched to 'Low' for this time.
GATE, Pin 7
The push-pull output Pin 7 is designed to trigger a power MOSFET.In order to protect the external FET, the maximum output voltage is limited by an integrated Zener diode.
Step-down Converter VHL Pin 8, VH Pin 9
The step-down converter produces a constant output voltage (VHtyp. 7 V) from the stepped-up voltage (VA1). When the integrated electronic power switch of the step-down converter (Pin VHL) is switched on, the coil current increases up to a limit determined by the controller. The switch is switched off when this limit is reached, and the energy stored in the coil is discharged into the capacitance CVH via an integrated diode. The circuit limits the maximum possible coil current to typ. 0.4 A. Pin VH is the controller input of the step-down converter.
NRES, Pin 12
As mentioned, the voltages VCC and VREF are continuously monitored within narrow limits to detect any overvoltages or undervoltages. A reset signal is issued at output NRES if overvoltages or undervoltages occur. NRES = High: NRES = Low: Normal operation Reset state
This function can trigger an error routine or a system reset in the event of disturbances.Pin NRES is an open collector output, which is protected by a 7-V Zener diode.
Rev. A1, 21-Apr-99
3 (8)
Preliminary Information
U6229B
ENVA3, Pin 13
Pin ENVA3 serves as the control input for the step-up converter ENVA3 = High/ open: ENVA3 = Low: Normal operation extended interruptions in the supply voltage. The duration depends on the external load and the size of CVA1.
AGND, Pin 18
Reference ground for voltages VA1, VH, VCC, VREF and internal reference
Step-up converter switched off
VKl15, Pin 14
VKl15 fulfills several monitoring functions with regard to the supply voltage. - Overvoltage detection The external FET of the step-up converter and the switch between VA1 and VBL are switched off in the event of overvoltages of VBatt > 27 V typ. The other parts of the circuit continue to function and are powered by the capacitor connected to VA1 during this time. A Zener diode rated at typ. 23 V is integrated in Pin VKl15 to protect against overvoltages. - Energy reserve state The step-up converter is also switched off at battery voltages of VBatt < 5.25 V. This leads to a reduced current requirement from VA1. As the step-up converter and the two linear controllers VCC and VREF are powered by VA1, the circuit is able to power a system even in the event of
RSET1, Pin 19
Pin 19 is connected to Pin 18 with a resistance of 35.7 kW (tolerance 1%). In the circuit, this resistance gives rise to a reference current from which various parameters such as the oscillator frequency, switch-off thresholds for step-up/step-down converter, threshold for overvoltage detection etc. are derived.
GND, Pin 20
Common ground
Starting Behavior
The step-up converter is started only if the following start-up conditions are fulfilled when it is switched on: > 5.25 V typ. VBatt V3 > 3.4 V typ. > 3.6 V VBatt - V3 The step-down converter is activated only if V3 > 7 V typ. This ensures that the step-down converter begins operation only once the step-up converter has started.
Absolute Maximum Ratings
Parameters Supply voltage Ambient temperature range Junction temperature range Storage temperature range Symbol VBatt Tamb Tj Tstg Min. -40 -40 -55 Typ. Max. 44 95 150 150 Unit V C C C
Thermal Resistance
Parameters Junction to case Junction ambient Symbol RthJC RthJA Value 30 90 Unit k/W k/W
Overvoltage protection according DIN 40839/4 and ISO/TR 7637/1 ESD: HBM 2 kV: MIL 883D M.3015.7 MM 200 V: ESD S. 5.2 - 1994
4 (8)
Rev. A1, 21-Apr-99
Preliminary Information
U6229B
Electrical Characteristics
VBatt = 6 V to 26 V, Tamb = -40 to 95C unless otherwise specified. Values measured at application example circuit figure 5. Parameters Oscillator Frequency constant Oscillator frequency Step-up converter Output voltage Test Conditions / Pins Symbol KOSC fOSC VVA1 VVA1 Min. Typ. 81 73 27.5 27.5 65 82 1.2 1.0 4.5 1.6 3.5 18 1 1.6 28.4 28.4 89 29.3 29.3 Max. Unit HzmF kHz V V % % A V V V V
COS1 = 1 nF
VCVB = 14 V Pin 3 I3 = 120 mA Output voltage VCVB > 5 V Pin 3 I3 = 30 mA Coefficient of efficiency VCVB = 5 V V3 = 27.5 V Coefficient of efficiency VCVB = 11 V V3 = 27.5 V Switch-off current LVB Pin 2 Voltage drop VBL - VA1; I2 = 0.9 I2max Voltage at pin GATE Output high Pin 7 Voltage at pin GATE Output low Pin 7 I7 = 100 mA Voltage at pin GATE Output low Pin 7 I7 = 5 mA Step-up converter - starting behavior Power-on-reset VBatt > 6 V Precharge CVA1 Step-up converter - Enable/Disable Supply voltage Threshold voltage V9 = 7 V Input voltage Pin 13 open Inpu current V13 = 0 V Step-down converter Output voltage I10 = -20 mA Pin 9 Coefficient of efficiency Switch-off current LVH Pin 8 Voltage drop VA1 - VHL; I8 = 0.9 I8max Forward voltage of freeIV8 = 0.9 I8max wheeling diode Step-down converter - starting behavior Switch threshold VBatt > 6 V VCC - regulator Output voltage IV10 = 0 mA to -90 mA Switch-off threshold Undervoltage Overvoltage Switch-on threshold Undervoltage Overvoltage
h h
I2 V2 - V3 V7 V7 V7
V3 VBatt - V3 VBatt V13 V13 I13 VH
2.6 2.1 5.5 0.8 4.4 - 1.9 6.5 70
3.4
4.2 5.5 5.5 2.0 7.0 - 0.4 7.5
V V V V V V V % A V V
5.25
h
I8 V3 - V8 V8
- 0.4 - 1.2
- 0.65 1.3
V3 V10 dV10off dV10off dV10on dV10on
6.3 4.85
7.6 5.15 230 230
V V mV mV mV mV
50 50
Rev. A1, 21-Apr-99
5 (8)
Preliminary Information
U6229B
Parameters VREF - regulator Output voltage Switch-off threshold Switch-on threshold Test Conditions / Pins IV11 = -1 mA to -14 mA Undervoltage Overvoltage Undervoltage Overvoltage Symbol V10 dV11off dV11off dV11on dV11on VBatt V14 V12 Ir12 Min. 4.88 Typ. Max. 5.12 150 150 Unit V mV mV mV mV V V
50 50 26 21 23 28 26 0.4 2
Overvoltage protection Threshold for overvoltage detection Battery monitor VBatt = 40 V NRES Saturation voltage I12 = 1.6 mA, NRES = low Reverse current V12 = 5 V
mA
V
VBatt RSET 35.7 kW RK15 249 W
19 18 17 16 15 14 13
CVREF 2.2 mF
12 11
5V Reference supply
20
U6229B
BYG 10
1 2 3 4 5 6 7 8 9 10
RM 220 W BYG10
COS1 1 nF SI9955DY
LVH 150
mH
7V Step-down converter 28.4 V Step-up converter
LVB 150
mH
CVB 100 mF
CVA1 1000 mF
CVH 33 mF
CVCC 15 mF
5V Logic supply
96 12285
Figure 5. Application example
6 (8)
Rev. A1, 21-Apr-99
Preliminary Information
U6229B
V Batt Squib 28.4 V supply
Sensor
4 Channel squib driver
Power supply
ADC
mC
96 12290
5V reference 5V logic
Figure 6. System block diagram
Package Information
Package SO20
Dimensions in mm
12.95 12.70 9.15 8.65 7.5 7.3
2.35
0.4 1.27 11.43 20 11
0.25 0.10 10.50 10.20
0.25
technical drawings according to DIN specifications 13038
1
10
Rev. A1, 21-Apr-99
7 (8)
Preliminary Information
U6229B
Ozone Depleting Substances Policy Statement
It is the policy of TEMIC Semiconductor GmbH to 1. Meet all present and future national and international statutory requirements. 2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances ( ODSs). The Montreal Protocol ( 1987) and its London Amendments ( 1990) intend to severely restrict the use of ODSs and forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these substances. TEMIC Semiconductor GmbH has been able to use its policy of continuous improvements to eliminate the use of ODSs listed in the following documents. 1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively 2 . Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency ( EPA) in the USA 3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C ( transitional substances ) respectively. TEMIC Semiconductor GmbH can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances.
We reserve the right to make changes to improve technical design and may do so without further notice. Parameters can vary in different applications. All operating parameters must be validated for each customer application by the customer. Should the buyer use TEMIC Semiconductors products for any unintended or unauthorized application, the buyer shall indemnify TEMIC Semiconductors against all claims, costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with such unintended or unauthorized use. TEMIC Semiconductor GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 ( 0 ) 7131 67 2594, Fax number: 49 ( 0 ) 7131 67 2423
8 (8)
Rev. A1, 21-Apr-99
Preliminary Information

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