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CS4124
Preliminary
CS4124
High Side PWM FET Controller
Description
The CS4124 is a monolithic integrated circuit designed primarily to control the rotor speed of permanent magnet, direct current (DC) brush motors. It drives the gate of an N channel power MOSFET or IGBT with a user-adjustable, fixed frequency, variable duty cycle, pulse width modulated (PWM) signal. The CS4124 can also be used to control other loads such as incandescent bulbs and solenoids. Inductive current from the motor or solenoid is recirculated through an external diode. The CS4124 accepts a DC level input signal of 0 to 5V to control the pulse width of the output signal. This signal can be generated by a potentiometer referenced to the onchip 5V linear regulator, or a filtered 0% to 100% PWM signal also referenced to the 5V regulator. The IC is placed in a sleep state by pulling the CTL lead below 0.5V. In this mode everything on the chip is shutdown except for the on-chip regulator and the overall current draw is less than 275A. There are a number of on-chip diagnostics that look for potential failure modes and can disable the external power MOSFET.
Features
s 150mA Peak PWM Gate Drive Output s Patented Voltage Compensation Circuit s 100% Duty Cycle Capability s 5V, 3% Linear Regulator s Low Current Sleep Mode s Overvoltage Protection s Boost Mode Power Supply s Output Inhibit
Applications Diagram
Package Option
VBAT 42.5H
16 Lead PDIP
1000F 1000F RS 10 470H
10K 10nF
1.5F
CFLT
.25F
ROSC 93.1K COSC 470pF
OUTPUT Gnd BOOST INH FLT IADJ ROSC COSC CTL PGnd ISENSE+ ISENSEPMP SNI RSNI
4
RCS1 CCS 51 .022F RCS2 51 RSENSE 4m
OUTPUT BOOST FLT ROSC COSC CTL PGnd VCC
1
Gnd INH IADJ ISENSE+ ISENSEPMP SNI VREG
VCC
100F .01F 10K 1F P1 10K 100K
VREG
Input
10K
RGATE 6
10K N1 10K 10K 10F
1M MOT+
MOT-
Consult Factory for 16 Lead SOIC Wide package.
Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: info@cherry-semi.com Web Site: www.cherry-semi.com
Rev. 4/26/99
1195
A
(R)
Company
CS4124
Absolute Maximum Ratings Storage Temperature ................................................................................................................................................-65C to 150C VCC .................................................................................................................................................................................-0.3V to 30V VCC Peak Transient Voltage (load dump = 26V w/series 10 resistor) ...........................................................................40V Input Voltage Range (at any input) ...........................................................................................................................-0.3V to 10V Maximum Junction Temperature ..........................................................................................................................................150C Lead Temperature Soldering Wave Solder (through hole styles only) ......................................................................................10 sec. max, 260C peak ESD Capability (Human Body Model) ....................................................................................................................................2kV Electrical Characteristics: 4V VCC 26V, -40C < TA < 125C, (unless otherwise specified)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
s VCC Supply Operating Current Supply Quiescent Current Overvoltage Shutdown s Control (CTL) Control Input Current Sleep Mode Threshold Sleep Mode Hysteresis
7V VCC 18V 4V VCC < 7V, 18V < VCC 26V VCC = 12V 26.5
5 170
10 15 275 29
mA mA A V
CTL = 0V to 5V 7V VCC 26V 4V VCC < 7V
-2 8% 50 10
0.1 10% 100
2 12% 150 150
A VREG mV mV
s Current Sense Differential Voltage Sense
7V VCC 18V IADJ = 1V and RCS1 = 51 IADJ = 4V and RCS1 = 51 4V VCC < 7V IADJ =1V and RCS1 = 51 18V < VCC 26V IADJ = 1V and RCS1 = 51 IADJ = 4V and RCS1 = 51
18 104 15
34 125 39
mV mV mV
15 102 -2 0.3
39 130 2
mV mV A
IADJ Input Current
4V VCC 26V IADJ = 0V to 5V
s Linear Regulator Output Voltage, VREG
VCC = 4V VCC = 13.2V VCC = 26V
2.0 4.85 4.85
5.15 5.20
V V V
s Inhibit Inhibit Threshold Inhibit Hysteresis
4V VCC 7V 7V VCC 26V
40% 100 150
50% 325
60% 500 500
VREG mV mV
s External Drive (OUTPUT) Output Frequency
4V VCC < 7V ROSC = 93.1k, COSC = 470pF 7V VCC 18V, ROSC = 93.1k, COSC = 470pF 18V < VCC 26V ROSC = 93.1k, COSC = 470pF 1196
10 17 17 20 20
25 23 25
kHz kHz kHz
CS4124
Electrical Characteristics: 4V VCC 26V, -40C < TA = 125C, (unless otherwise specified)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
s External Drive (OUTPUT): continued Voltage to Duty Cycle 4V VCC < 7V Conversion VCC = 13V, CTL = 1V VCC = 13V, CTL = 2V 7V VCC 18V VCC = 13V, CTL = 30% VREG VCC = 13V, CTL = 55.8% VREG 18V < VCC 26V VCC = 13V, CTL = 1. 5V VCC = 13V, CTL = 3. 5V Output Rise Time 4V VCC 26V RGATE = 6, CGATE = 5nF Output Fall Time 4V VCC 26V RGATE = 6, CGATE = 5nF Output Sink Current 4V VCC < 7V RGATE = 6, CGATE = 5nF 7V VCC 26V RGATE = 6, CGATE = 5nF Output Source Current 4V VCC < 7V RGATE = 6, CGATE = 5nF 7V VCC 26V RGATE = 6, CGATE = 5nF Output High Voltage IOUT = 1mA Output Low Voltage IOUT = -1mA s Charge Pump (DRV) Boost Voltage
65 100 28.3 56.0 11.8 34.2 .25 .30 150 300 150 300 VBOOST - 1.7
75
% % % % % % s s mA mA mA mA V V
36.3 64.0 21.8 44.2 1 1
1.3
VCC + 6.4 Package Lead Description
V
PACKAGE LEAD #
LEAD SYMBOL
FUNCTION
16 Lead PDIP 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 OUTPUT BOOST FLT ROSC COSC CTL PGnd VCC VREG SNI PMP ISENSEISENSE+ IADJ INH Gnd MOSFET gate drive Boost voltage Fault time out capacitor Oscillator resistor Oscillator capacitor Pulse width control input Power ground for on chip clamp Positive power supply input 5V linear regulator Sense inductor current Collector of boost power transistor Current sense minus Current sense plus Current limit adjust Output Inhibit Ground 1197
CS4124
Application Information Theory Of Operation Oscillator The IC sets up a constant frequency triangle wave at the COSC lead whose frequency is related to the external components ROSC and COSC, by the following equation: Frequency = 0.83 ROSC x COSC
120% VCC = 8V 100%
pensated duty cycle. The transfer is set up so that when VCC = 14V the duty cycle will equal VCTL divided by VREG. For example at VCC = 14V, VREG = 5V and VCTL = 2.5V, the duty cycle would be 50% at the output. This would place a 7V average voltage across the load. If VCC then drops to 10V, the IC would change the duty cycle to 70% and hence keep the average load voltage at 7V.
The peak and valley of the triangle wave are proportional to VCC by the following: VVALLEY = 0.1 x VCC VPEAK = 0.7 x VCC This is required to make the voltage compensation function properly. In order to keep the frequency of the oscillator constant the current that charges COSC must also vary with supply. ROSC sets up the current which charges COSC. The voltage across ROSC is 50% of VCC and therefore: IROSC = 0.5 x VCC ROSC
Duty Cycle( %)
80% VCC = 14V 60% VCC = 16V 40%
20%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% CTL Voltage (% of VREG)
IROSC is multiplied by (2) internally and transferred to the COSC lead. Therefore: ICOSC = The period of the oscillator is: T = 2COSC x VPEAK - VVALLEY ICOSC VCC ROSC
Figure 1: Voltage Compensation
5V Linear Regulator There is a 5V, 5mA linear regulator available at the VREG lead for external use. This voltage acts as a reference for many internal and external functions. It has a drop out of approximately 1.5V at room temperature. Current Sense and Timer The IC differentially monitors the load current on a cycle by cycle basis at the ISENSE+ and ISENSE- leads. The differential voltage across these two leads is amplified internally and compared to the voltage at the IADJ lead. The gain, AV is set internally and externally by the following equation: AV = VI(ADJ) ISENSE+ - ISENSE= 37000 1000 + RCS
The ROSC and COSC components can be varied to create frequencies over the range of 15Hz to 25kHz. With the suggested values of 93.1k and 470pF for ROSC and COSC , the nominal frequency will be approximately 20 kHz. IROSC, at VCC = 14V, will be 66.7 A. IROSC should not change over a more than 2:1 ratio and therefore COSC should be changed to adjust the oscillator frequency. Voltage Duty Cycle Conversion The IC translates an input voltage at the CTL lead into a duty cycle at the OUTPUT lead. The transfer function incorporates Cherry Semiconductor's patented Voltage Compensation method to keep the average voltage and current across the load constant regardless of fluctuations in the supply voltage. The duty cycle is varied based upon the input voltage and supply voltage by the following equation: 2.8 x VCTL Duty Cycle = 100% x VCC An internal DC voltage equal to: VDC = (1.683 x VCTL) + VVALLEY is compared to the oscillator voltage to produce the com-
The current limit (ILIM) is set by the external current sense resistor (RSENSE) placed across the ISENSE+ and ISENSE- terminals and the voltage at the IADJ lead. 1000 + RCS 37000 VI(ADJ) RSENSE
ILIM =
x
The RCS resistors and CCS components form a differential low pass filter which filters out high frequency noise generated by the switching of the external MOSFET and the associated lead noise. RCS also forms and error term in the gain of the ILIM equation because the ISENSE+ and ISENSEleads are low impedance inputs thereby creating a good current sensing amplifier. Both leads source 50A while the chip is in run mode. IADJ should be biased between 1V and 4V. When the current through the external MOSFET 1198
CS4124
Application Information: continued exceeds ILIM, an internal latch is set and the output pulls the gate of the MOSFET low for the remainder of the oscillator cycle (fault mode). At the start of the next cycle, the latch is reset and the IC reverts back to run mode until another fault occurs. If a number of faults occur in a given period of time, the IC "times out" and disables the MOSFET for a long period of time to let it cool off. This is accomplished by charging the CFLT capacitor each time an over current condition occurs. If a cycle goes by with no overcurrent fault occurring, an even smaller amount of charge will be removed from CFLT. If enough faults occur together, eventually CFLT will charge up to 2.4V and the fault latch will be set. The fault latch will not be reset until CFLT discharges to 0.6V. This action will continue indefinitely if the fault persists. The off time and on time are set by the following: Off Time = CFLT x 2.4V - 0.6V 4.5A 2.4V - 0.6V IAVG Sleep State This device will enter into a low current mode (< 275A) when CTL lead is brought to less than 0.5V. All functions are disabled in this mode, except for the regulator. Inhibit When the inhibit is greater than 2.5V the internal latch is set and the external MOSFET will be turned off for the remainder of the oscillator cycle. The latch is then reset at the start of the next cycle. Overvoltage Shutdown The IC will disable the output during an overvoltage event. This is a real time fault event and does not set the internal latch and therefore is independent of the oscillator timing (i.e. asynchronous). There is 325mV (typical) of hysteresis on the overvoltage function. There is no undervoltage lockout. The device will shutdown gracefully once it runs out of headroom. Reverse Battery The CS4124 will not survive a reverse battery condition. A series diode is required between the battery and the VCC lead for reverse battery. Load Dump A 10 resistor, (RS) is placed in series with VCC to limit the current into the IC during 40V peak transient conditions.
On Time = CFLT x where:
IAVG = (295.5A x DC ) - [4.5A x (1 - DC )] IAVG = (300A x DC ) - 4.5A DC = PWM Duty Cycle Boost Switch Mode Power Supply The CS4124 has an integrated boost mode power supply which charges the gate of the external high-side MOSFET to greater than 5V above VCC. Three leads are used for voltage boost. They are Boost, PMP and SNI. The PMP lead is the collector of a darlington tied NPN power transistor. This device charges the inductor during its on time. The boost lead is the input to chip from the external reservoir capacitor. The SNI lead is the emitter of the power NPN and is connected externally to the RSNI resistor. The power supply is controlled by the oscillator. At the start of a cycle an R-S flip flop is set the internal power NPN transistor is turned on and energy begins to build up in the inductor. The RSNI resistor sets the peak current of the inductor by tripping a comparator when the voltage across the resistor is 450mV. The flip flop is reset and the inductor delivers its stored energy to the load. The ripple voltage (VRIPPLE) at the Boost lead is controlled by CBOOST. A snubber circuit, made up of a series resistor and capacitor, is required to dampen the ringing of the inductor. A value of 4 is recommended for RSNI. A zener diode is needed between the boost output voltage and the battery. This will clamp the boost lead to a specified value above the battery to prevent damage to the IC. A 9 volt zener diode is recommended.
1199
CS4124
Package Specification
PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA
D Lead Count 16L PDIP Metric Max Min 19.69 18.67 English Max Min .775 .735
Thermal Data RJC RJA typ typ
16 Lead PDIP 42 80
C/W C/W
Plastic DIP (N); 300 mil wide
7.11 (.280) 6.10 (.240)
8.26 (.325) 7.62 (.300) 3.68 (.145) 2.92 (.115)
1.77 (.070) 1.14 (.045)
2.54 (.100) BSC
.356 (.014) .203 (.008)
0.39 (.015) MIN. .558 (.022) .356 (.014) Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same.
REF: JEDEC MS-001
D
Ordering Information
Part Number CS4124YN16
Rev. 4/26/99
Description 16L PDIP 1200
Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information.
(c) 1999 Cherry Semiconductor Corporation

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