Rainbow Electronics MAX8707 - Manual (Page 7)

MAX8707
Multiphase, Fixed-Frequency Controller for
AMD Hammer CPU Core Power Supplies
_______________________________________________________________________________________ 7
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1. V
CC
= V SHDN = 5V, OSC = REF, V
VPS
= V
FBS
= V
CRSN
= V
CRSP
= V
CSP_
= 1.20V, V
SUSV
= 0.8V, OFS = SUS =
GNDS = PGND = SKIP = GND, D0–D4 set for 1.20V (D0–D4 = 01110). T
A
= -40°C to +85°C, unless otherwise specified.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN MAX UNITS
Output Undervoltage-Protection
Threshold
V UVP
Measured at VPS with respect to 70% of the
unloaded nominal output voltage
-40 +40 mV
Undervoltage, measured at VPS with
respect to 87.5% of the unloaded output
voltage, falling edge, 15mV hysteresis
-40 +40
VROK Threshold
Overvoltage, measured at VPS with respect
to 112.5% of the unloaded output voltage,
rising edge, 15mV hysteresis
-40 +40
mV
VROK Output Low Voltage I SINK = 3mA 0.4 V
V CC Undervoltage-Lockout
Threshold
V
UVLO(VCC)
Rising edge, hysteresis = 20mV, PWM_
disabled below this level
4.10 4.45 V
DROOP AND TRANSIENT RESPONSE
DC Droop Amplifier Offset -2 +2 mV
DC Droop Amplifier
Transconductance
(CRS Sense Enabled)
G m(VPS)
∆I
VPS / (N x ∆V
CRS ); V VPS = V CRSN = 1.2V,
V CRSP - V CRSN = -60mV to +60mV,
N = number of phases enabled
190 210 µS
DC Droop Amplifier
Transconductance
(CRS Sense Disabled)
G m(VPS)
∆I
VPS / ( Σ∆V
CS ), V CRSP = V CC ,
V VPS = V CSN _ = 1.2V,
V CSP _ - V CSN _ = -60mV to +60mV
190 210 µS
Transient-Droop Transresistance R TRANS
Current-sense gain (A CS = 10 typ) divided
by the voltage preamplifier
transconductance (G
m(TRC) = 2mS typ)
4.50 5.25 k Ω
CURRENT LIMIT AND BALANCE
Current-Sense Input Preamplifier
Offsets
CSP_ - CSN_ -2.5 +2.5 mV
ILIM(AVE) Input Range
(Adjustable Mode)
V
ILIM(AVE)
V REF
- 1.0
V REF
- 0.2
V
ILIM(AVE) Average Current-Limit
Threshold Voltage
(Positive, Default)
V AVELIMIT CRSP - CRSN; ILIM(AVE) = V CC 20 30 mV
V ILIM(AVE) = V REF - 0.2V 5 15 ILIM(AVE) Average Current-Limit
Threshold Voltage
(Positive, Adjustable)
V AVELIMIT CRSP - CRSN
V ILIM(AVE) = V REF - 1.0V 44 56
mV
ILIM(AVE) Average Current-Limit
Threshold Voltage (Negative)
CRSP - CRSN; ILIM(AVE) = V CC -31 -19 mV
ILIM(AVE) Current-Limit Default
Switchover Threshold
3
V
CC
- 0.4
V